The collar should just graze your neck without constricting it when buttoned. If turning your head causes the collar to turn with it, it’s too tight. You should be able to comfortably fit 1 finger inside of your buttoned collar without it choking you. Two fingers is too much (even though the image says otherwise) and looks a little sloppy to me.
The shoulder seam should be right where your shoulder starts sloping down to your arm. Somewhere above the armpit, basically. If the seam starts creeping past where your shoulder slopes down, its too big. If it lands before your shoulder slopes, it’s too small.
Armholes should be comfortable in motion – they should not be so tight that they cut into the underarm. However, they shouldn’t be so loose that there’s a bunch of excess fabric around the armpit. An easy way to check this is to tuck your shirt into your pants – if lifting your arms 45 degrees lifts your shirt out of your pants more than an inch or so, your armholes are probably too low.
They should not be so tight that you can see the details of your arms, but they should also not be so loose as to billow and bunch at the wrist. When you bend your arm, your cuff should not move more than an inch up your wrist. If it does, it’s likely too tight.
The sleeve/cuff should end right at the bend of your wrist.
When speaking of cuffs, there’s two major types: French and Barrel. They should both fit about the same.
With the cuffs buttoned, and your arms at your side, when you bend your wrist so your palms are facing the ground, the sleeves should barely touch the top of your hand (see the video above for details). Ideally, they should be able ¼” above the top of your hand, but if it’s just lightly grazing, that’s OK. Anything more than that and the sleeves need to be hemmed. You want this length so your shirt sleeve slightly peeks out from under your blazer or suit jacket sleeve.
Your cuffs should be tight enough to not restrict movement, but not so loose that your thumb notch at your wrist doesn’t stop the cuff from moving up your hand. It should be a bit looser than a properly fitting watch.
You shouldn’t be able to pinch more than 2-3” of fabric on either side of the waist. The body of the shirt should fit closely around your torso, no matter what your shape or size. A billowy shirt is no excuse, especially if you’re a larger man.
If you’ll wear the shirt untucked (not really what I’d recommend with a dress shirt) but either way, it should end around the mid-crotch area. Any longer than that and it’s too long and should only be worn tucked in. Shorter than that just doesn’t look good.
If you’ll always be wearing the shirt tucked in, which I recommend for dress shirts, then the longer the better. Traditionally, dress shirts were made very long – usually ending at the bottom or past the crotch. If you have this type of shirt, NEVER, EVER wear the shirt untucked. I can’t tell you how many times I see older guys wearing these types of shirts untucked and I vomit a little inside my mouth whenever I see it. It looks horrible.
My Dress Shirt Recommendations
Check out my Semi-Spread Collar Dress Shirt article for my favorite dress shirts.