Rab jacket sizing

I'm looking to buy a Rab Positron Pro jacket as an over-it-all/belay layer, but there aren't any stores near me that stock Rab gear so I can't try it on before ordering. I've read that a belay jacket is already sized to fit over other layers, but also that Rab tends to run slimmer than many American brands. I'm normally a medium in jackets and I'm wondering whether I should stick with that or order a large. Layers that I would commonly wear underneath it are Patagonia Capilene midweight shirt (size S), Patagonia R1 (size S), and Black Diamond First Light jacket (size M). Does anyone who's familiar with this or similar Rab jackets have a recommendation?

I'm rocking the Xeon and it's true to size for me. I wear mediums in US brands and my Rab is medium. I have no problem layering as you list above. Love it!

M should be fine. If you wear a S in baselayers, L is going to be too big. 

RAB his more of a slim fit (which I am not) as do most of the Euro brands. I tried RAB on in Boulder and they made me feel a little self conscious about my widening middle that I can't seem to get rid of.

I found that rab products run just a tad small.  Not enough to size down though

I have the neutrino pro in M, which should be a similar fit to the positron pro. Feels pretty common medium size, (comparable to OR).  I can fit a base layer, light softshell, light synth puffy, and even a hardshell under it pretty well - all M sizes.  I'm probably on the lower side of Medium though FWIW.  I can attest to some RAB jackets running small though - I have the nebula pro and it can only fit half of those layers under (though I guess its not as much of a true belay puffy), and is a bit tight around the armpits even with minimal layers.

I have 2 jackets from Rab, both Medium and they fit me perfectly. I'm 6'0" and 180.

I have three rab jackets. I typically wear a small in other brands. I’m 5’6”, 140lbs. The rab small is very tight on me and the mediums fit better.

5'8" 140 here. I wear a medium in everything else but my Rab Microlight Alpine is a large and fits perfectly with typical layering.

5'8" 165 42 inch chest.  My Rab Atmos rain jacket is a medium and I sure wouldn't want it any snugger - might have been better with.a large but the medium was a 70% off closeout and there was no large on hand.- I make it work.

I wear a small in Patagonia (R1 fits great, capilene is a little tight) and medium in Black Diamond as well and with Rab I wear small (got an electron and some sun shirt) and medium in the outer shell layer. Personally I'd stick with a small, but a medium may work if you're doing a ton of layering.

I've had many Rab down jackets & for belay purposes, I'd definitely size up to the large.  I find Rab does run a bit smaller/slimmer than other brands.

Climbing friend! If you are eating the American meal of supersized most fattening then please order the large jacket and do not complain of European "slim" sizing. But if you are lying in coldest mountain stream before making flash most pleasurable with forearms strong but svelte then medium shall fit fine.

Yeah, it's not that Rab runs slim or uses an athletic fit, it's that Rab straight up uses Euro sizes because it's a UK company.

So, choose appropriately based on how your size in 'Murican maps to Euro sizes. For example, XL in American is always XXL in Euro, (and potentially up to 3X in Asia depending on country of origin and brand).

A Neutrino M will be plenty big for the OP. I have had one and a Positron. The above post is largely false, except for the part about Rab being a UK company.

Bullshit. I've tried a bunch of stuff at the Rab store by Denver Beer, and this is a well-known difference between American and Euro sizes, it's far from just Rab.

Eli R wrote: I'm looking to buy a Rab Positron Pro jacket as an over-it-all/belay layer, but there aren't any stores near me that stock Rab gear so I can't try it on before ordering. I've read that a belay jacket is already sized to fit over other layers, but also that Rab tends to run slimmer than many American brands. I'm normally a medium in jackets and I'm wondering whether I should stick with that or order a large. Layers that I would commonly wear underneath it are Patagonia Capilene midweight shirt (size S), Patagonia R1 (size S), and Black Diamond First Light jacket (size M). Does anyone who's familiar with this or similar Rab jackets have a recommendation?

If you have broad shoulders definitely size up. 

Eli R wrote: I'm looking to buy a Rab Positron Pro jacket as an over-it-all/belay layer, but there aren't any stores near me that stock Rab gear so I can't try it on before ordering. I've read that a belay jacket is already sized to fit over other layers, but also that Rab tends to run slimmer than many American brands. I'm normally a medium in jackets and I'm wondering whether I should stick with that or order a large. Layers that I would commonly wear underneath it are Patagonia Capilene midweight shirt (size S), Patagonia R1 (size S), and Black Diamond First Light jacket (size M). Does anyone who's familiar with this or similar Rab jackets have a recommendation?

What's your height/weight? I'm 5'10.5, ~150lbs, and usually float between a Small and Medium.  I got a Rab Neutrino not too long ago, and ordered the S and M.  The S definitely worked, but I went with the Medium just so it would fit over anything I could possibly want to wear under it.  It's definitely roomy, however.  If you wear a S in an R1, I think you'd be swimming in a Rab L.

Tradgic Yogurt wrote: Yeah, it's not that Rab runs slim or uses an athletic fit, it's that Rab straight up uses Euro sizes because it's a UK company.

So, choose appropriately based on how your size in 'Murican maps to Euro sizes. For example, XL in American is always XXL in Euro, (and potentially up to 3X in Asia depending on country of origin and brand).

Not necesarily as simple as that. Even among UK companies, Rab runs slim. Montane (another UK company) is the same. I have to size up to fit in either of them, which usually means that the jacket ends up being too long, so I just stick to other brands. 

Thanks all for the input. For anyone who might be referencing this thread in the future, I ordered the medium, and it was definitely the way to go - fit very well over all my other layers with room to move comfortably (but not excessively roomy, as the large certainly would have been). I am on the smaller side of medium for jackets - 5'10" and around 145lb with a generally lanky frame.