Atom SL vs Proton FL: Key Differences [Jan 2023 Guide]

This article is revised after Arc'teryx FW23 update.

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Proton FL.

I've been publishing in-depth helpful guides to almost all Arc'teryx jackets for more than two years now (see full post list at the bottom).

Now that the summer is here, let's take a look at how the differences between Proton FL vs Atom SL play out.

Atom SL (Super Light) and Proton FL (Fast & Light) are the two most breathable, least warm alternatives you can find in Arc'teryx's insulated jacket line-up.

They're both best suited for chilly summer and/or spring mornings, followed by a high output activity (primarily rock / alpine climbing).

Latest on the blog:

13 Dec 2022: Arc'teryx Alpha Parka Review: The most impressive jacket of all time
8 Dec 2022: Arc'teryx ReGEAR: OutdoorCrunch exclusive promo code!
24 Nov 2022: Nuclei SV: Warmest Arc'teryx synthetic
7 Nov 2022: 2023 Thorium Hoody is in - as well as the new Thorium Parka (yes, parka)
2 Nov 2022: Beta Insulated Jacket: Pit zips AND two way zipper!
7 October 2022: Proton Hybrid Hoody is live! The ultimate do it all?
5 October 2022: DropHood vs StormHood: Pros/cons and best uses
5 September 2022: Reviewing Arc'teryx Fall Winter 22/23 Gear
5 August 2022: 5 things all Arc'teryx newbies should know

#A sidenote here: Arc'teryx's PDF guide to jackets is GOOOLLLLDDDDD. Absolutely check that out too if you're interested in buying one.

These jackets are more alike than they're different.

Proton FL is slightly warmer, slightly more breathable, slightly more durable and comes with an inch longer hemline
Atom SL is more wind resistant

Short answer is that unless you'll be using the jacket under windy conditions 90+% of the time, I'd probably recommend you to get the more versatile option, the Proton FL.

Warmth

Neither of these jackets will provide substantial warmth. Like I clarified earlier, they aren't even designed to do so anyway.

Proton FL is insulated with Octa Loft throughout the entire jacket. The Atom SL, on the other hand, is insulated with Coreloft Compact only around the core, which holds it warmth back.

I'd recommend you to take a look at the lowest temperatures they're expected to be worn comfortably by an average person (both are positioned at the bottom):

Arc'teryx Jackets: Temperature Ratings

Name	Est. Temp (F/C)	Review	Pit venting?	Stuffs into itself?	Two way zipper?	Type	Fill Power	Fill Weight (grams)	Fill Volume (FP x FW)	Synthetic Insulator (SI)	SI Amount	Face Fabric	Activity	Fit	Weight	Length (CB)
Arc'teryx Alpha (Men's - Women's)	-18/-28	Review	No	Yes	Yes	Down	850	296	251,600	Coreloft	90 g/m²	N30r 2L GoreTex Infinium	Climbing	Regular	805 g / 1 lb 12.4 oz	86 cm / 34 in
Feathered Friends Khumbu	-17/-27		No	Yes	No	Down	900	378	340,200	Primaloft Gold	200 g	Pretex Shield XT	All Round	Regular	960 g / 2 lb 2 oz	?
Arc'teryx Ceres SV (Men's - Women's)	-15/-26	Review	No	Yes	Yes	Down	850	240	204,000	Coreloft	?	Arato 30	All Round	Regular	880 g / 1 lb 15 oz	86 cm / 34 in
Mountain Equipment K7 (Men's)	-13/-25		No	Yes	Yes	Down	800	300	240,000	N/A	N/A	30D Drilite	All Round	Regular	820 g / 1 lb 13 oz	76 cm / 30 in
Rab Positron Pro (Men's)	-13/-25		No	Yes	Yes	Down	800	300	240,000	N/A	N/A	40D Pertex Quantum Pro	All Round	Regular	740 g / 1 lb 10 oz	85 cm / 33.5 in
Arc'teryx Therme SV (Men's)	-11/-24	Review	No	No	Yes	Parka	750	211	158,250	Coreloft	60 g/m²	2L Gore-Tex	Around Town	Regular	1.072 kg / 2 lb 5.8 oz	96 cm / 37.75 in
Patagonia Grade VII (Men's)	-11/-24		No	No	Yes	Down	800	335	268,000	N/A	N/A	1.2 oz 15 & 20D Perfex Quantum	Around Town	Regular	743 g / 1 lb 10.1 oz	83 cm / 32.5 in
Arc'teryx Firebee AR (Men's - Women's)	-10/-23	Review	No	Yes	Yes	Down	800	225	180,000	N/A	N/A	Arato 7 & 10	All Round	Regular	680 g / 1 lb 8 oz	79 cm / 31 in
Mountain Equipment Exo (Men's)	-10/-23		No	Yes	Yes	Down	800	265	212,000	N/A	N/A	Nylon	All Round	Regular	770 g / 1 lb 11.2 oz	79 cm / 31 in
Arc'teryx Thorsen (Men's)	-7/-22	Review	No	No	Yes	Parka	750	192	144,000	Coreloft	60 g/m²	90D 2L Gore-Tex	Around Town	Regular	1.1 kg / 2 lb 5.4 oz	91 cm / 36 in
Patagonia Frozen Range (Men's - Women's)	-6/-21	Review	No	No	No	Parka	700	268	187,600	N/A	N/A	4 oz 75-denier polyester	Around Town	Regular	1.253 kg / 2 lb 12.2 oz	84 cm / 33 in
Mountain Equipment Li. Ec. (Men's - Women's)	-5/-20		No	No	Yes	Down	700	295	206,500	N/A	N/A	50D Drilite	All Round	Regular	822 g / 1 lb 13 oz	72 cm / 28 in
Arc'teryx Patera Long (Women's)	-2/-19		No	No	Yes	Parka	750	74	55,500	Coreloft	60 + 80 g/m²	2L Gore-Tex	Around Town	Regular	1.1 kg / 2 lb 6.8 oz	117.5 cm / 46.25 in
Rab Neutrino Pro (Men's - Women's)	-2/-19		No	Yes	Yes	Down	800	212	169,600	N/A	N/A	20D Pertex Quantum Pro	All Round	Regular	585 g / 1 lb 8.6 oz	77 cm / 30.3 in
Arc'teryx Dually Belay (Men's)	0/-18	Review	No	Yes	Yes	Synthetic	N/A	N/A	N/A	ThermaTek	92 g/m²	30D Nylon	Around Town	Regular	705 g / 1 lb 9 oz	84 cm / 33 in
Arc'teryx Centrale (Women's)	0/-18	Review	No	No	Yes	Parka	750	157	117,750	Coreloft	60 g/m²	N90p Nylon	Around Town	Regular	885 g / 1 lb 15.2 oz	95 cm / 37.5 in
Arc'teryx Camosun (Men's)	0/-18	Review	No	No	No	Parka	750	105	78,750	Coreloft	140 g/m²	N150p-X Gore-Tex	Around Town	Trim	960 g / 2 lb 1.9 oz	80 cm / 31.5 in
Arc'teryx Cerium SV (Men's)	0/-18	Review	No	Yes	No	Down	850	162	137,700	Coreloft	80 + 140 g/m²	Arato 7 & 10	All Round	Regular	415 g / 14.6 oz	69.5 cm / 27.4 in
Arc'teryx Revet (Men's)	2/-17		No	No	Yes	Parka	750	?		N/A	N/A	20d nylon/spandex double weave	Around Town	Regular	755 g / 1 lb 10.6 oz	91 cm / 36 in
Arc'teryx Piedmont (Men's)	3/-16		No	Yes	Yes	Parka	750	218	163,500	N/A	N/A	Arato 10	Around Town	Regular	515 g / 1 lb 2.2 oz	82 cm / 32.25 in
Arc'teryx Fission SV (Men's - Women's)	3/-16	Review	No	No	Yes	Synthetic	N/A	N/A	N/A	Coreloft Continuous	90 + 65 g/m²	N80p-X Gore-Tex 2L	All Round	Regular	890 g / 1 lb 15.4 oz	81 cm / 31.8 in
Arc'teryx Alpha Lightweight (Men's)	3/-16		No	Yes	Yes	Down	850	117	99,450	Coreloft Compact	40 g/m²	Hadron 2L Gore-Tex Infinium	Climbing	Regular	540 g / 1 lb 3 oz	?
Outdoor Research Sup. Alp. (Men's - Women's)	3/-16		No	No	Yes	Down	800	182	145,600	N/A	N/A	30D Pertex Quantum Pro	All Round	Regular	825 g / 1 lb 13.1 oz	85 cm / 33.5 in
Arc'teryx Alessa Long (Women's)	3/-16		No	No	No	Parka	N/A	N/A	N/A	Coreloft	80 + 120 g/m²	N90p 2L Gore-Tex	Around Town	Regular	1.015 kg / 2 lb 3.8 oz	123 cm / 48.5 in
Patagonia Tres 3-in-1 (Men's - Women's)	3/-16	Review	No	No	No	Parka	700	118	82,600	N/A	N/A	5.5 oz polyester	Around Town	Regular	1.307 kg / 2 lb 14.1 oz	85 cm / 33.5 in
Arc'teryx Radsten Parka (Men's)	3/-16		No	No	No	Parka	N/A	N/A	N/A	Coreloft Compact	120 g/m²	NP100d Gore-Tex 2L	Around Town	Regular	745 g / 1 lb 10.3 oz	82 cm / 32.25 in
Rab Electron Pro (Men's - Women's)	5/-15		No	Yes	Yes	Down	800	180	144,000	N/A	N/A	20D Pertex Quantum Pro	All Round	Regular	525 g / 1 lb 2.5 oz	74 cm / 29 in
Arc'teryx Therme Parka (Men's)	5/-15	Review	No	No	Yes	Parka	750	120	90,000	Coreloft	60 + 80 g/m²	P75d Polyester	Around Town	Regular	991 g / 2 lb 3 oz	85 cm / 33.5 in
Arc'teryx Macai (Men's)	5/-15	Review	Yes, zips	No	No	Down	750	69	51,750	Coreloft Compact	60 + 100 g/m²	N40p-X 3L Gore-Tex	Ski/Snowboard	Regular	1 kg / 2 lb 4 oz	76 cm / 30 in
Arc'teryx Nuclei SV (Men's)	5/-15	Review	No	Yes	Yes	Synthetic	N/A	N/A	N/A	Coreloft Continuous	180 g/m2 + 90 g/m2	Arato 15	Climbing	Regular	600 g / 1 lb 5.2 oz	81 cm / 31.8 in
Patagonia DAS Parka (Men's)	5/-15		No	Yes	Yes	Parka	N/A	N/A	N/A	PrimaLoft Gold Insulation Eco	133 + 40 g	Pertex Quantum Pro	Around Town	Regular	555 g / 1lb 3.6 oz	84 cm / 33 in
Arc'teryx Patera (Women's)	5/-15	Review	No	No	Yes	Parka	750	58	43,500	Coreloft	60 + 80 g/m²	2L Gore-Tex	Around Town	Trim	867 g / 1 lb 14.6 oz	93 cm / 37 in
Black Diamond Access Down (Men's - Women's)	7/-14		No	Yes	Yes	Down	700	155	108,500	N/A	N/A	30D ripstop nylon	All Round	Regular	442 g / 15.6 oz	76 cm / 29.75 in
Arc'teryx Kappa (Men's)	7/-14	Review	No	No	Yes	Synthetic	N/A	N/A	N/A	Coreloft Continuous	140 g/m²	N70p Gore Thermium	All Round	Regular	755 g / 1 lb 10.6 oz	80 cm / 31.5 in
Arc'teryx Prema Down Coat (Women's)	7/-14		No	No	Yes	Parka	750	92	69,000	N/A	N/A	Nylon	Around Town	Regular	794 g / 1 lb 12 oz	117 cm / 46.1 in
Arc'teryx Radsten Insulated (Men's)	7/-14		No	No	No	Parka	N/A	N/A	N/A	Coreloft Compact	120 g/m²	NP100d Gore-Tex 2L	Around Town	Regular	715 g / 1 lb 9.2 oz	73 cm / 28.75 in
Rab Microlight Alpine (Men's - Women's)	7/-14		No	Yes	No	Down	700	153	107,100	N/A	N/A	30D Pertex Quantum	All Round	Regular	466 g / 1 lb 0.5 oz	72 cm / 28.5 in
Arc'teryx Thorium (Men's - Women's)	7/-14	Review	No	Yes	Yes	Down	750	140	105,000	Coreloft	80 + 140 g/m²	Arato 30	All Round	Regular	517 g / 1 lb 2.2 oz	71.5 cm / 28.1 in
Feathered Friends Eos	8/-13		No	Yes	No	Down	900	105	94,500	N/A	N/A	Pertex Quantum	All Round	Regular	306 g / 10.8 oz	?
Arc'teryx Thorium AR (Men's - Women's)	8/-13	Review	No	Yes	No	Down	750	130	97,500	Coreloft	80 + 140 g/m²	Arato 30	All Round	Regular	490 g / 1 lb 1.3 oz	72 cm / 28.3 in
Patagonia Macro Puff (Men's - Women's)	8/-13	Review	No	No	No	Synthetic	N/A	N/A	N/A	PlumaFill	135 + 90 g	10D Recycled nylon ripstop	All Round	Regular	435 g / 15.3 oz	79 cm / 31 in
Arc'teryx Macai LT (Men's)	8/-13		Yes, zips	No	No	Down	750	49	36,750	Coreloft Compact	60 g/m²	N40p-X 3L Gore-Tex	Ski/Snowboard	Regular	855 g / 1 lb 14.2 oz	74 cm / 29.1 in
Arc'teryx Seyla (Women's)	8/-13		No	No	Yes	Parka	750	92	69,000	N/A	N/A	Arato 10	Around Town	Regular	507 g / 1 lb. 1.9 oz.	87 cm / 34.4 in
Patagonia Fitz Roy (Men's - Women's)	8/-13		No	Yes	No	Down	800	128	102,400	N/A	N/A	20D Nylon	All Round	Regular	632 g / 1lb 6.3 oz	74 cm / 29 in
Arc'teryx Koda (Men's)	8/-13		No	No	No	Parka	N/A	N/A	N/A	Coreloft	80 + 140 g/m²	N80p-X Gore-Tex	Around Town	Regular	720 g / 1 lb 9.4 oz	75 cm / 29.5 in
Patagonia Vosque 3-in-1 (Women's)	10/-12	Review	No	No	No	Parka	N/A	N/A	N/A	ThermoLite	100 g	65% nylon, 35% polyester	Around Town	Regular	1.360 kg / 3 lb	90 cm / 35.5 in
Patagonia City Storm Down (Men's - Women's)	12/-11		No	Yes	No	Parka	700	191	133,700	N/A	N/A	4.2 oz polyester	All Round	Regular	468 g / 16.5 oz	91 cm / 36 in
Patagonia Jackson Glacier (Men's - Women's)	12/-11	Review	No	No	Yes	Parka	700	141	98,700	N/A	N/A	3.6 oz 50D polyester	Around Town	Regular	880 g / 1 lb 15 oz	79 cm / 31 in
Arc'teryx Sensa (Women's)	14/-10		No	No	Yes	Parka	N/A	N/A	N/A	Coreloft Compact	120 g/m²	NP100d Gore-Tex 2L	Around Town	Relaxed	785 g / 1 lb 11.7 oz	86 cm / 34 in
Patagonia Hi Loft Down (Men's - Women's)	14/-10	Review	No	Yes	No	Down	600	177	106,200	N/A	N/A	1.4 oz 30D polyester	All Round	Regular	540 g / 1 lb 3 oz	76 cm / 30 in
REI Magma 850 Hoodie 2.0 (Men's - Women's)	14/-10		No	Yes	No	Down	850	120	102,000	N/A	N/A	Pertex mini ripstop nylon	All Round	Regular	340 g / 13.75 oz	74 cm / 29.25 in
Arc'teryx Beta Insulated Coat (Women's)	16/-9	Review	No	No	Yes	Synthetic	N/A	N/A	N/A	Coreloft	80 g/m² + 120 g/m²	2L 40D Gore-Tex	Around Town	Regular	600 g / 1 lb 5.2 oz	?
Arc'teryx Atom AR (Men's - Women's)	18/-8	Review	Yes, mesh	No	No	Synthetic	N/A	N/A	N/A	Coreloft Continuous	120 g/m2 + 80 g/m2 + 60 g/m2	30D Tyono	All Round	Regular	475 g / 1 lb	74 cm / 29.1 in
Patagonia Downdrift (Men's - Women's)	18/-8		No	No	No	Down	600	279	167,400	N/A	N/A	4.2 oz polyester	Around Town	Regular	1.014 kg / 2 lb 3.8 oz	?
Arc'teryx Magnus (Men's)	19/-7		No	No	No	Parka	N/A	N/A	N/A	Coreloft	80 g	N60p Gore-Tex 2L	Around Town	Regular	690 g / 1 lb 8.3 oz	83 cm / 32.5 in
Arc'teryx Agrium (Men's - Women's)	21/-6		No	Yes	No	Down	850	117	99,450	N/A	N/A	Arato	All Round	Regular	365 g / 12.9 oz	75 cm / 29.5 in
Patagonia AlpLight Down (Men's - Women's)	21/-6		No	Yes	No	Down	800	100	80,000	N/A	N/A	0.8 oz 10D polyester	All Round	Slim	270 g / 9.5 oz	74 cm / 29 in
Arc'teryx Beta Insulated (Men's - Women's)	21/-6	Review	Yes, zips	No	Yes	Synthetic	N/A	N/A	N/A	Coreloft Continuous	80 g/m²	2L 40D Gore-Tex	All Round	Regular	680 g / 1 lb 8 oz	78.5 cm / 31 in
Patagonia Topley (Men's)	23/-5		No	No	Yes	Down	700	172	120,400	N/A	N/A	6 oz polyester	All Round	Regular	1.133 kg / 2 lb 8 oz	77 cm / 30.5 in
Arc'teryx Alpha IS (Men's)	23/-5		No	Yes	Yes	Synthetic	N/A	N/A	N/A	Coreloft Continuous	65 g/m²	N40p-X 2L Gore-Tex	Climbing	Regular	610 g / 1 lb 5.5 oz	78 cm / 30.75 in
Rab Xenon 2.0 (Men's - Women's)	23/-5		No	Yes	Yes	Synthetic	N/A	N/A	N/A	PrimaLoft Silver	60 g	30D Pertex Quantum	All Round	Regular	385 g / 13.6 oz	71.5 cm / 28.1 in
Patagonia Down Sweater (Men's - Women's)	23/-5	Review	No	Yes	No	Down	800	150	120,000	N/A	N/A	1.4 oz 20x30D polyester	All Round	Regular	428 g / 15.1 oz	67 cm / 26.25 in
Arc'teryx Ralle Parka (Men's)	25/-4		No	No	Yes	Parka	N/A	N/A	N/A	Coreloft	80 g/m²	2L 40D Gore-Tex	Around Town	Regular	735 g / 1 lb 9.9 oz	?
Patagonia Silent Down (Men's - Women's)	26/-3	Review	No	No	No	Down	700	109	76,300	N/A	N/A	2.2 oz polyester	Around Town	Regular	585 g / 1 lb 4.7 oz	74 cm / 29 in
Arc'teryx Therme Insulated (Men's)	26/-3	Review	No	No	No	Synthetic	N/A	N/A	N/A	Coreloft Compact	40 g/m²	2L Gore-Tex	Around Town	Regular	960 g / 2 lb 1.9 oz	73 cm / 28.75 in
Arc'teryx Cerium (Men's - Women's)	26/-3		No	Yes	No	Down	850	113	96,050	Coreloft	80 + 100 g/m²	Arato 15	All Round	Trim	335 g / 11.8 oz	?
Mountain Hardwear GW/2 (Men's - Women's)	28/-2		No	Yes	No	Down	800	85	68,000	N/A	N/A	10D Ripstop Nylon	All Round	Trim	250 g / 8.8 oz	70 cm / 27.5 in
Arc'teryx Cerium LT (Men's - Women's)	28/-2	Review	No	Yes	No	Down	850	102	86,700	Coreloft	80 + 100 g/m²	Arato 10	All Round	Trim	305 g / 10.8 oz	72 cm / 28.3 in
Arc'teryx Nuclei FL (Men's - Women's)	32/0	Review	No	Yes	No	Synthetic	N/A	N/A	N/A	Coreloft Continuous	65 g/m²	Arato 10r	Climbing	Trim	325 g / 11.5 oz	75 cm / 29.5 in
Patagonia DAS Light (Men's - Women's)	34/1		No	Yes	Yes	Synthetic	N/A	N/A	N/A	PlumaFill	65 g	0.8-oz 10-denier Pertex Quantum Pro	Climbing	Regular	320 g / 11.3 oz	77 cm / 30.5 in
Patagonia Micro Puff (Men's - Women's)	36/2	Review	No	Yes	No	Synthetic	N/A	N/A	N/A	PlumaFill	65 g	Pertex Quantum	All Round	Trim	298 g / 10.5 oz	75 cm / 29.5 in
Patagonia Isthmus (Men's)	36/2		No	No	No	Parka	N/A	N/A	N/A	ThermoGreen	60 g	4.2 oz polyester	Around Town	Regular	895 g / 1 lb 15.6 oz	70 cm / 27.5 in
Arc'teryx Proton LT (Men's - Women's)	37/3	Review	No	No	No	Synthetic	N/A	N/A	N/A	Coreloft Compact	80 g/m2 + 60 g/m2	Fortius Air 20	Climbing	Trim	375 g / 13.2 oz	75 cm / 29.4 in
Patagonia Nano Puff (Men's - Women's)	37/3	Review	No	Yes	No	Synthetic	N/A	N/A	N/A	PrimaLoft Gold Insulation Eco	60 g	22D Polyester	All Round	Regular	363 g / 12.8 oz	71.5 cm / 28 in
Arc'teryx Norvan SL Ins. (Men's - Women's)	39/4		No	Yes	No	Synthetic	N/A	N/A	N/A	Coreloft Compact	40 g/m²	Gore-Tex ShakeDry	Running	Trim	270 g / 9.5 oz	71.5 cm / 28.1 in
Patagonia Nano Air (Men's - Women's)	41/5	Review	No	No	No	Synthetic	N/A	N/A	N/A	FullRange	60 g	33D Nylon ripstop	All Round	Trim	318 g / 11.2 oz	?
Arc'teryx Atom LT (Men's - Women's)	43/6	Review	Yes, mesh	No	No	Synthetic	N/A	N/A	N/A	Coreloft Continuous	60 g/m²	20D Tyono	All Round	Trim	375 g / 13.2 oz	74 cm / 29.1 in
Arc'teryx Cerium SL (Men's - Women's)	43/6	Review	No	Yes	No	Down	850	58	49,300	Coreloft	40 + 100 g/m²	Arato 7	All Round	Trim	215 g / 7.6 oz	69 cm / 27.2 in
Arc'teryx Proton Hybrid (Men's - Women's)	46/8	Review	No	No	No	Synthetic	N/A	N/A	N/A	Coreloft Compact	40 g/m²	Fortius™ Air 50	All Round	Trim	365 g / 12.9 oz	?
Arc'teryx Proton FL (Men's)	48/9	Review	No	No	No	Synthetic	N/A	N/A	N/A	Octa Loft	94 g/m²	Fortius Air 20	Climbing	Trim	323 g / 11.4 oz	77 cm / 30.4 in
Arc'teryx Atom SL (Men's - Women's)	52/11	Review	Yes, mesh	No	No	Synthetic	N/A	N/A	N/A	Coreloft Compact	40 g/m²	20D Tyono	All Round	Trim	245 g / 8.6 oz	72 cm / 28.3 in
REI Stormhenge Hybrid (Men's - Women's)	Testing		Yes, zips	No	No	Down	850	?		N/A	N/A	40D + 80D	All Round	Regular	900 g / 1 lb 15.75 oz	80 cm / 31.5 in
Arc'teryx Monitor Insulated (Women's)	Testing		No	No	Yes	Parka	N/A	N/A	N/A	Coreloft	80 + 100 g/m²	40D 3L Gore-Tex	Around Town	Oversized	645 g / 1 lb 6.8 oz	93 cm / 37 in
Arc'teryx Coelle (Women's)	Testing		No	No	Yes	Parka	N/A	N/A	N/A	Coreloft	80 + 140 g/m²	40D 2L Gore-Tex	Around Town	Regular	460 g / 1 lb 0.2 oz	93 cm / 37 in

View full table at https://outdoorcrunch.com/best-arcteryx-jacket/.

If you're confused now and don't know which jacket best corresponds to your own needs, then follow the advice given in https://arcteryx.com/us/en/shop/jacket-finder/.

The temperature ratings in this list are intended to represent the lowest temperatures you can wear each jacket without feeling uncomfortably cold.

Keep in mind that these are only approximate values, assuming:

worn over a shirt only and no shell over,
during daily use (strolls, power walks etc at most - no high output activities),
with light wind,
and when it's dry out.

These values applicable to your torso only. Your hands, legs and feet are still subject to their own additional insulation.

The best practice is usually to use this table for comparing each jacket to one another, rather than pinpointing their ratings.

Also, ratings will best respond to males. As most women tend to run colder than men, for women, shifting these ratings a bit is recommended.

Always opt for the warmer option when in doubt. For jackets with Atom AR level warmth and beyond, recommended is almost always the hooded models.

Also see: Arc'teryx Shells

Name	Bottom line	Activity	Review	Breathability	Weather Res.	Durability	Packability	Temp (F/C)	Pit zips?	Two way zipper?	Stuffs into itself?	Hood?	Face Fabric	Fit	Weight	Length	Measurements
Alpha FL (Men's - Women's)		Climbing		4/10	5/10	6/10	10/10	N/A	No	No	Yes	StormHood	Hadron 3L Gore-Tex	Trim	209 g / 7.4 oz	76.5 cm / 30 in	[Men's / Women's]
Alpha SL (Men's - Women's)		Climbing		3/10	4/10	6/10	9/10	N/A	No	No	Yes	StormHood	N40p 3L Gore-Tex	Trim	326 g / 11.5 oz	77.5 cm / 30.5 in	[Men's / Women's]
Alpha AR (Men's - Women's)	Go-to climbing harshell.	Climbing	Review	8/10	7/10	8/10	4/10	N/A	Yes	No	No	StormHood	N40d & N80d Most Rugged 3L Gore-Tex Pro	Regular	430 g / 15.2 oz	79.5 cm / 31.25 in	[Men's]
Alpha SV (Men's - Women's)	Strongest climbing hardshell.	Climbing	Review	8/10	10/10	10/10	3/10	N/A	Yes	No	No	StormHood	N100d Most Rugged 3L Gore-Tex Pro	Regular	510 g / 1 lb 2 oz	78 cm / 30.75 in	[Men's]
Alpha IS (Men's)		Climbing		7/10	5/10	5/10	8/10	23/-5	No	Yes	Yes	StormHood	N40p-X 2L Gore-Tex	Regular	610 g / 1 lb 5.5 oz	78 cm / 30.75 in
Beta (Men's - Women's)		All Round		5/10	5/10	4/10	5/10	N/A	No	No	No	StormHood	N30p-X 3L Gore-Tex	Fitted	300 g / 10.6 oz	76 cm / 30 in
Beta Long (Men's)		All Round	Review	5/10	8/10	8/10	3/10	N/A	No	No	No	StormHood	N80p 3L Gore-Tex	Regular	441 g / 15.6 oz	85 cm / 33.5 in
Beta Coat (Women's)		All Round		7/10	5/10	4/10	5/10	N/A	No	Yes	No	StormHood	3L Gore-Tex	Regular	320 g / 11.3 oz	?	[Men's / Women's]
Beta LT Hadron (Men's - Women's)		All Round		5/10	5/10	4/10	5/10	N/A	No	No	No	StormHood	Hadron 3L Gore-Tex	Fitted	255g / 9 oz	76 cm / 30 in
Beta LT (Men's - Women's)	Beta AR alternative.	All Round	Review	8/10	7/10	8/10	5/10	N/A	Yes	No	No	StormHood	N40d 3L Gore-Tex	Fitted	395 g / 13.9 oz	76 cm / 30 in
Beta Insulated (Men's - Women's)	Best insulated shell.	All Round		10/10	4/10	4/10	2/10	21/-6	Yes	Yes	No	StormHood	N40d 2L Gore-Tex	Regular	680 g / 1 lb 8 oz	78.5 cm / 31 in	[Men's / Women's]
Beta Insulated Coat (Women's)	Beta Insulated alternative.	All Round		7/10	4/10	4/10	2/10	16/-9	No	Yes	No	StormHood	N40d 2L Gore-Tex	Regular	600 g / 1 lb 5.2 oz	?	[Men's / Women's]
Beta AR (Men's - Women's)	Go-to all-round harshell.	All Round	Review	8/10	8/10	8/10	4/10	N/A	Yes	No	No	DropHood	N40r-X & N80p-X Most Rugged 3L Gore-Tex Pro	Regular	460 g / 1 lb	76 cm / 30 in
Beta SV (Men's - Women's)	Strongest all-round harshell.	All Round	Review	8/10	10/10	9/10	3/10	N/A	Yes	No	No	StormHood	N80p-X Most Rugged 3L Gore-Tex Pro	Regular	495 g / 1 lb 1.5 oz	79 cm / 31 in	[Men's / Women's]
Alpine Guide (Men's - Women's)		All Round		8/10	10/10	9/10	3/10	N/A	Yes	No	No	StormHood	N80d-X Most Rugged 3L Gore-Tex Pro	Regular	480g / 1 lb 0.9 oz	?	[Men's]
Gamma SL (Men's - Women's)	A trimmer Gamma LT.	All Round	Review	7/10	2/10	6/10	5/10	N/A	No	No	No	StormHood	Fortius 1.0	Trim	310 g / 10.9 oz	74 cm / 29.1 in	[Men's / Women's]
Gamma LT (Men's)	A fleeceless, trimmer Gamma MX.	All Round	Review	7/10	3/10	7/10	3/10	N/A	No	No	No	StormHood	Wee Burly	Regular	545 g / 1 lb 3.2 oz	76 cm / 30 in	[Men's / Women's]
Gamma MX (Men's - Women's)	A softshell with a fleece.	All Round	Review	6/10	4/10	8/10	3/10	N/A	No	No	No	StormHood	Fortius 2.0	Regular	555 g / 1 lb 3.6 oz	74 cm / 29.1 in	[Men's / Women's]
Rush (Men's - Women's)	Go-to ski jacket.	Skiing	Review	8/10	9/10	9/10	3/10	N/A	Yes	No	No	StormHood	N80p-X & N100p-X 3L Most Rugged Gore-Tex Pro	Regular	590 g / 1 lb 4.8 oz	79.5 cm / 31.25 in	[Men's]
Sabre (Men's)	Alternative to Rush.	Skiing		8/10	8/10	8/10	2/10	N/A	Yes	No	No	StormHood	N80p-X 3L Gore-Tex	Regular	705 g / 1 lb 8.9 oz	79 cm / 31 in
Sentinel (Women's)		Skiing		8/10	8/10	8/10	2/10	N/A	Yes	No	No	StormHood	N70p 3L Gore-Tex	Regular	370 g / 13.1 oz	?
Macai (Men's)	Go-to insulated ski jacket.	Skiing	Review	10/10	8/10	9/10	1/10	5/-15	Yes	No	No	DropHood	N40p-X 3L Gore-Tex	Regular	1 kg / 2 lb 3.3 oz	75 cm / 29.5 in
Macai LT (Men's)	A lighter Macai with StormHood.	Skiing		8/10	7/10	8/10	1/10	8/-13	Yes	No	No	StormHood	N40p-X 3L Gore-Tex	Regular	855 g / 1 lb 14.2 oz	?	[Men's]
Andessa (Women's)	Go-to insulated ski jacket.	Skiing		10/10	Testing	Testing	1/10	8/-13	Yes	No	No	DropHood	N40d 3L Gore-Tex	Trim	869 g / 1 lb 14.7 oz	?
Andessa Shell (Women's)	Non-insulated Andessa.	Skiing		5/10	Testing	Testing	3/10	N/A	No	No	No	DropHood	N70p 3L Gore-Tex	Trim	560 g / 1 lb 3.8 oz	?
Theriss Down (Women's)		Skiing		8/10	6/10	7/10	2/10	Testing	Yes	No	No	StormHood	N80p 2L Gore-Tex	Regular	709 g / 1 lb 9 oz	?
Rush IS (Women's)	An insulated Rush.	Skiing		5/10	Testing	Testing	9/10	16/-9	No	No	Yes	StormHood	Gore-Tex Infinium	Regular	515 g / 1 lb 2.2 oz	?
Sentinel IS (Women's)		Skiing		Testing	Testing	Testing	Testing	21/-6	Yes	No	No	StormHood	N80p 2L Gore-Tex	Regular	600 g / 1 lb 5.2 oz	?	[Women's]
Ski Guide (Men's - Women's)		Skiing		Testing	Testing	Testing	Testing	N/A	Yes	No	No	DropHood	N80d Most Rugged 3L Gore-Tex Pro	Regular	570 g / 1 lb 4.1 oz	?
Micon Heather		Skiing		Testing	Testing	Testing	Testing	N/A	Yes	No	No	StormHood	NP100-d 3L Gore-Tex	Regular	685 g / 1 lb 8.2 oz	83 cm / 32.5 in	[Men's]
Micon (Men's)		Skiing		Testing	Testing	Testing	Testing	N/A	Yes	No	No	StormHood	N80p 3L Gore-Tex	Regular	685 g / 1 lb 8.2 oz	83 cm / 32.5 in	[Men's]
Cassiar (Men's)		Skiing	Review	8/10	7/10	8/10	3/10	N/A	Yes	No	No	DropHood	N70p 3L Gore-Tex	Trim	820 g / 1 lb 12.9 oz	74.5 cm / 29.3 in	[Women's]
Cassiar LT (Men's)		Skiing	Review	6/10	6/10	6/10	5/10	N/A	Yes	No	No	DropHood	N70p 3L Gore-Tex	Trim	605 g / 1 lb 5.3 oz	75 cm / 29.5 in	[Women's]
Ravenna (Women's)		Skiing	Review	8/10	7/10	8/10	3/10	N/A	Yes	No	No	DropHood	N70s-4 3L Gore-Tex	Trim	725 g / 1 lb 9.6 oz	69.5 cm / 27.4 in	[Men's]
Ravenna LT (Women's)		Skiing	Review	6/10	6/10	6/10	5/10	N/A	Yes	No	No	DropHood	N70p 3L Gore-Tex	Trim	540 g / 1 lb 3 oz	69 cm / 27.2 in	[Men's]
Procline (Men's)		Skiing		Testing	Testing	Testing	Testing	N/A	Yes	No	No	StormHood	N70p Gore-Tex Infinium	Trim	720 g / 1 lb 9.4 oz	76 cm / 30 in	[Women's]
Shashka Stretch (Women's)		Skiing		Testing	Testing	Testing	Testing	N/A	Yes	No	No	StormHood	N70p Gore-Tex Infinium	Trim	670 g / 1 lb 7.6 oz	71 cm / 28 in	[Women's]
Sabre AR (Men's)		Skiing	Review	7/10	8/10	7/10	7/10	N/A	Yes	No	No	StormHood	N70p 3L Gore-Tex	Regular	700 g / 1 lb 8.7 oz	79 cm / 31 in	[Men's]
Sentinel AR (Women's)		Skiing	Review	7/10	8/10	7/10	7/10	N/A	Yes	No	No	StormHood	N70p 3L Gore-Tex	Regular	590 g / 1 lb 4.8 oz	72.5 cm / 28.5 in	[Women's]
Sabre LT (Men's)		Skiing	Review	7/10	8/10	7/10	8/10	N/A	Yes	No	No	StormHood	N80p 3L Gore-Tex	Regular	660 g / 1 lb 7.3 oz	83 cm / 32.5 in
Sentinel LT (Women's)		Skiing	Review	7/10	8/10	7/10	8/10	N/A	Yes	No	No	StormHood	N80p 3L Gore-Tex	Regular	565 g / 1 lb 3.9 oz	73.5 cm / 29 in
Incendia (Women's)		Skiing	Review	8/10	9/10	9/10	3/10	N/A	Yes	No	No	StormHood	NP100d 3L Gore-Tex	Trim	610 g / 1 lb 5.5 oz	79 cm / 31 in	[Women's]
Indencia IS		Skiing		Testing	Testing	Testing	Testing	Testing	Yes	No	No	StormHood	N80p 2L Gore-Tex	Regular	?	78 cm / 30.75 in	[Men's / Women's]
Norvan LT (Men's - Women's)	Go-to running jacket.	Running		5/10	5/10	8/10	6/10	N/A	No	No	No	Standard	N13p 3L Gore-Tex	Fitted	190 g / 6.7 oz	?	[Women's]
Squamish (Men's - Women's)	Trimmer, lighter, packable running jacket.	Running	Review	5/10	4/10	7/10	9/10	N/A	No	No	Yes	StormHood	30D Tyono	Trim	140 g / 4.9 oz	77.5 cm / 30.5 in	[Women's]
Norvan SL Ins. (Women's)		Running		Testing	Testing	Testing	Testing	39/4	No	No	Yes	Standard	Gore-Tex ShakeDry	Trim	270 g / 9.5 oz	71.5 cm / 28.1 in	[Women's]
Cita (Women's)		Running	Review	7/10	4/10	5/10	10/10	N/A	No	No	Yes	Standard	Lumin	Trim	120 g / 4.2 oz	67.5 cm / 26.5 in	[Men's]
Cita SL (Women's)		Running	Review	7/10	4/10	4/10	10/10	N/A	Yes	No	Yes	Standard	Permeair 20	Trim	65 g / 2.3 oz	61.5 cm / 24.2 in	[Men's]
Incendo (Men's)		Running	Review	7/10	4/10	5/10	10/10	N/A	No	No	Yes	Standard	Lumin	Trim	125 g / 4.4 oz	?
Incendo SL (Men's)		Running	Review	7/10	4/10	4/10	10/10	N/A	No	No	Yes	Standard	Permair 20 & Canim	Trim	80 g / 2.8 oz	73 cm / 28.75 in	[Men's / Women's]
Incendo Airshell		Running		Testing	Testing	Testing	Testing	N/A	No	No	Yes	Standard	?	?	?	?	[Men's]
Norvan SL (Men's - Women's)		Running	Review	7/10	6/10	8/10	8/10	N/A	No	No	Yes	Standard	Gore-Tex Infinium	Trim	120 g / 4.2 oz	77 cm / 30.4 in	[Women's]
Trino SL (Men's)		Running	Review	8/10	5/10	7/10	6/10	N/A	No	No	No	Standard	Gore-Tex Infinium	Trim	340 g / 12 oz	74 cm / 29.1 in	[Men's / Women's]
Trino SL Anorak (Women's)		Running	Review	8/10	7/10	8/10	7/10	N/A	No	No	No	Standard	Gore-Tex Infinium	Trim	290 g / 10.2 oz	65 cm / 25.5 in	[Men's / Women's]
Nodin (Men's - Women's)		Running		8/10	5/10	5/10	10/10	N/A	No	No	Yes	Standard	20D Tyono	Trim	155 g / 5.5 oz	75 cm / 29.5 in	[Men's / Women's]
Solano (Men's - Women's)		Around Town	Review	Testing	Testing	Testing	Testing	N/A	No	No	No	Standard	Gore-Tex Infinium	Relaxed	355 g / 12.5 oz	72 cm / 28.3 in
Venda Anorak (Women's)		Around Town		Testing	Testing	Testing	Testing	N/A	No	No	No	Standard	Gore-Tex	Relaxed	255 g / 9 oz	75.5 cm / 29.7 in
Zeta FL (Men's - Women's)		Hiking		4/10	6/10	4/10	6/10	N/A	No	No	No	StormHood	N20r 2L Gore-Tex	Trim	221 g / 7.8 oz	76 cm / 30 in	[Men's / Women's]
Zeta SL (Men's - Women's)		Hiking	Review	3/10	5/10	4/10	5/10	N/A	No	No	No	StormHood	2L Gore-Tex	Trim	310 g / 10.9 oz	77.8 cm / 30.6 in	[Men's]
Zeta LT (Men's - Women's)		Hiking		5/10	7/10	8/10	5/10	N/A	No	No	No	StormHood	N40P-X 3L Gore-Tex	Trim	335 g / 11.8 oz	78 cm / 30.75 in	[Men's]
Zeta AR (Men's)		Hiking		7/10	8/10	7/10	4/10	N/A	Yes	No	No	StormHood	3L Gore-Tex	Regular	425 g / 15 oz	80 cm / 31.5 in

Breathability

Going from top to bottom (Atom SL, LT and AR respectively), the warmth increases and the breathability decreases.

Although Atom SL is the most breathable unit in the Atom line, Proton FL still breathes more.

Actually, as I explained before, this is also the case between Proton LT and Atom LT as well.

Water, wind and abrasion resistances

While neither are comparable to outer layers (shell or belay jackets) at all, they'll fill the bill for spring and summer activities.

They're comparable in terms of water resistances, but Atom SL (Tyono 20) offers a slightly more wind resistance and slightly less abrasion resistance compared to Proton FL (Fortius Air 20).

They're both DWR coated.

What is DWR by the way?

DWR is a coating.

It's basically sprayed on to the surface of these jackets as a finish. It stands for Durable Water Repellent - which means that water will be repelled under wet conditions instead of soaking into the fabric.

DWR also decreases dry time.

It's a good thing these jackets are coated in DWR, but pay attention to the fact that DWR is a coating - meaning that it will wear off over time.

Which is why you might want to invest in a DWR spray such as this one for after treatment.

As you see, there's a strong correlation between FP x FW and temperature ratings, but not more than, say, 80%. I explained why this happens here in this post of mine.

Fit and size measurements

For a small size Atom SL:

Chest width: 107 cm
Shoulder length: 16.4 cm
Waist width: 98.4 cm
Front length: 67.3 cm
Center back length: 71 cm

For a small size Proton FL:

Chest width: 109 cm
Shoulder length: 14.8 cm
Waist width: 101.0 cm
Front length: 75.7 cm
Center back length: 75.7 cm

Both offer a trim cut.

Conclusion

I'd probably get the Proton FL. It's more versatile.

A helpful video review:

Comments

Julie says

February 15, 2021 at 1:48 am

Hello,
What ti wear over the proton fl in winter to protect from wind and little more heat?
mike says

April 12, 2021 at 1:45 am

here is my current setup for winter ice climbing;

Base Layer : OR echo t-shirt (Synthetic moisture wicking tee shirt)
Mid/insultation layer : Patagonia R1 fleece
Shell : Arcteryx Alpha FL

This setup works great when combine it all together when climbing, but i often overheat on the approach. If i take the shell off the wind cuts right through the R1. I am hesitating between the Proton FL and the new atom sl anork. Any suggestion?
Randy says

December 16, 2021 at 9:25 am

Thanks for the review. I have one Proton FL and am trying to purchase another. They seem to have disappeared or are no longer in stock. Supply problems or has this great model been discontinued by Arcteryx? This jacket is my go-to mid-layer when it’s too warm (or I’m too warm) for my Atom LT, Proton LT, etc. Fantastic Arcteryx product. I have learned a lot (and purchased a lot) after reading reviews and comparisons on your website. Really appreciate your analysis!