The Arc'teryx Atom Hoody Men's, especially in the Black Sapphire version, has a pretty versatile fit, which is why it's a hit with lots of outdoor folks. Now, when it comes to sizing, most folks find that it fits true to size. But, you might want to keep a couple of things in mind to make sure it suits your comfort and style.
From what we've found, the jacket generally fits as expected, but if you're thinking about layering up for chillier days, you might consider going a size up. For instance, there's someone who's 5'11" and 150 lbs who thought the medium fit perfectly, but suggested sizing up if you like a more relaxed fit or plan on wearing heavier layers underneath.
According to the manufacturer's description, a medium is geared for a 40-inch chest and a 34-inch waist, which can give you a good comparison with your own measurements.
Our data shows that people really appreciate the jacket for its synthetic insulation, which keeps you warm even when things get damp, and for its lightweight yet durable build. It's made with really solid materials like the Tyono 20 denier shell and Coreloft 60 insulation.
That said, opinions vary on the fabric's feel and the updated fit, particularly in the chest and hip areas. So, if those spots are a concern, thinking about a size adjustment could be worth it.
Overall, if you prefer a snug fit with some room for light layering, your usual size should work fine. But if you're aiming for more ease and layering flexibility, going up a size might be more comfortable without losing the jacket's great performance.
