Blazers (or Sport Coats):
Figuring your jacket size is a simple lesson: take a measuring tape and wrap it around thefullest part of your chest (typically, under your armpits). If you measure 40 inches around your chest, then your chest size is 40 inches and, likewise, your suit jacket size is 40. Easy enough.
The letter after the jacket size is thelength of your jacket (both body and sleeve). Your options are short (S), regular (R), long (L), or extra long (XL).
Generally, a ‘short’ is suitable for people 5’8” and shorter; a ‘regular’ is good for individuals 5’9” - 6’ feet tall; between 6’1” and 6’4” is considered ‘long;’ lastly, people 6’5” and taller need ‘extra long.’
Guys, this is a general breakdown and a great starting point. Based on your torso length, arm length, and other factors, you may not fit into the recommended length for your height group.
The most important thing to know is: DO NOT base your dress pant size on your jeans size. Why? Jeans and casual pants are "vanity sized" (not to mention the fabric has more stretch). Just because the pants claim they are a size 34 does not mean they actually measure 34 inches around.
The best thing is to physically measure the waistband of a pair ofdress pantsor slacks that fits you well and sits at your waist (not lower, like jeans are often worn). If you don’t have dress pants,measure your actualwaist (just above where you’d wear your belt).
Once you have measured your waist or the waistband of your favorite dress pants, that number is yourpant size. So, if your waist is 34 inches around, your pant size is 34 or 34W (W stands for waist).
Don't sweat the sizing too badly. Manufacturers think ahead and include extra fabric at the waist and seat in case the pant needs to be let out (or taken in) up to two additional inches.
Pants also come with aninseam measurement. This represents the inner seam of the pant leg, from the seat seam below the zipper down to the bottom hem. Pants can be purchased unhemmed or pre-hemmed - in this case, it will have two numbers separated by an ‘x’ (e.g. 34x32). That second number is your inseam.
There are many different styles that can be expressed by inseam length, but that’s a story for a different day. Just know that in traditional men’s tailoring, most dress pants should hit the back of your dress shoe and have a small break in the front.
That's it, men. Now go out and conquer your day.