2XB means 2X Big. At Westport, a 2XB fits an 18 to 18.5 inch neck, a 50 to 52 inch chest and a 46 to 48 inch waist, with a 33/34 sleeve. The "B" sizes add room through the body. The "T" sizes, like XLT and 3XT, add length through the sleeves and torso. If you have ever stood in front of a size list wondering which letters belong to you, this is the plain-English version, with the five sizing myths that send the most guys home with the wrong shirt.

The letters, decoded

1. B is Big. 1XB through 6XB. More room in the chest, waist and middle, with sleeves close to regular length.
2. T is Tall. LT, XLT and 2XT through 5XT. Longer sleeves and a longer body, with a trimmer waist than the matching big size.
3. MT is Mid-Tall. Used on Westport No-Tuck shirts, typically for men between 6'1" and 6'4" who need a little more length than a big size but less than a tall. Depending on your torso length, a taller man may actually be "Mid-Tall" if the torso's ratio to the bottom half is shorter. It all depends on where you want your shirt's hem to hit your pants.
4. The number is the size step. Each step up adds about 4 inches of chest. A 2XB is a 50 to 52 inch chest, a 3XB is 54 to 56.

Our full big and tall size chart lists every size by neck, chest, waist and sleeve.

Myth: 2XB is just another name for 2XL

A regular 2XL is a standard pattern scaled up, and the measurements change from brand to brand. A 2XB is cut on a big-man pattern from the start, so the extra room goes where a bigger body needs it: the chest, the waist and the seat of the shirt. If a 2XL fits your chest but pulls across your stomach, a big size is usually the fix.

Myth: Tall sizes are only longer

Put an XLT next to a 1XB on the chart and the difference is clear. They share the same neck (17 to 17.5) and the same chest (46 to 48). The XLT has a trimmer waist, 40 to 42 inches against 42 to 44, and a much longer sleeve, 36/37 against 32/33. Tall sizes are built for a longer, leaner frame, and big sizes are built for a fuller one.

Myth: If your 2XB feels tight, buy a 3XB

Find out what is tight before you size up. If the chest fits but the sleeves stop short of your wrist, try a 2XT instead of a 3XB, as long as your waist falls in the 2XT range of 44 to 46 inches. Going up a full big size adds about 4 inches around the body, which turns a short sleeve problem into a baggy shirt. If the buttons pull across the chest, the next big size is the right move.

Myth: Your height tells you which size to buy

Height is a good starting point for shirt length. Westport No-Tuck shirts use it directly: big sizing for men up to 6 feet, mid-tall from 6'1" to 6'4", and tall for men over 6'4". Chest and waist still decide the number. A 6'5" man with a 54 inch chest is a 3XT, and a 6'5" man with a 46 inch chest is an XLT.

Myth: Big and tall works the same way in pants

Pants use waist and inseam instead of letters. When a pant comes in "Regular" and "Long," Regular lines up with the big sizes and Long lines up with the tall sizes. Start with your waist measurement, then pick the length that matches the shirt sizes you already wear. Our business casual guide covers rise, the other measurement that decides whether pants sit right on a bigger frame.

Measure once, buy with confidence

You need a soft tape and two minutes. Measure your neck (the number on a dress shirt collar) with two fingers between the tape and your skin. Measure your chest over a shirt, under your arms and straight across your shoulder blades. For sleeve, bend your elbow and measure from the middle of your back, below your neck, across your shoulder and elbow to your wrist. Measure your waist over your shirt, where you wear your pants. Match those numbers to the size chart, and use the row where most of them land. Questions? Westport's team takes calls at 1-877-WESTPORT (937-8767).