I usually vacillate between L and XL but prefer XL to hide my tummy a bit and I ordered a size smaller than usual after reading the reviews had read. Shirt runs true to size - chest measurement for a tall man was 22 inches armpit to armpit, but I usually aim for 23 inches. It fits great and is true to size so as you can see the tummy is not hidden at all! But it's a training and muscle tee, so it doesn't matter. The shirt gets 5 stars from me because as soon as you touch it you can tell that the shirt is made of a fairly thick, high-quality material. This shirt should last a long time. Update: I ended up returning the L and got 2 XL as I love this shirt but I ordered a size too small. Size XL fits perfectly. For a good comparison, in my photos, navy heather is large and burgundy heather is XL. You can see that the XL doesn't flatter anything and sits looser. Very happy with these shirts!