Give us any one of three numbers (your pant waist size, a tape measurement where you wear your belt, or the length of a belt that fits you now) and we will give you your belt size in US inches and EU centimeters. The famous rule is pant size plus 2, and we will show you why it works.
Belts have one job and two numbers, and people mix up the numbers constantly. Your pant size describes a garment; your belt size describes a path around the outside of that garment, through loops and over a shirt. The path is longer. That is the entire mystery behind the plus-2 rule, and it is why buying a belt in your pant size gives you a belt that fastens, resentfully, on its last hole.
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Three ways in, one answer out
The most reliable source is a belt that already fits: measure from where the leather folds at the buckle pin to the hole you actually use, and that distance is your belt size directly. Second best is a tape threaded through your belt loops over your normal clothes. The pant tag is the least precise source (vanity sizing means a "34" garment often measures 35 or 36), but the plus-2 convention absorbs most of that error, which is why the rule survives.
The formula
from pant size: belt = pant + 2, rounded up to even
from waist tape: belt = measurement, rounded up to even
from a belt: belt = buckle fold to used hole, rounded to even
EU size = belt × 2.54, to the nearest 5 cm
Belts are sold in even inch sizes measured to the middle hole, and EU belts in 5 cm steps measured the same way.
Worked example
Your jeans say 33. Add 2: 35, and since belts come in even sizes, round up to 36. A size 36 belt is 91.4 cm, so in an EU shop you buy the 90. Cross-check with the tape: through the loops you measure 35.5 inches, which also rounds up to a 36 belt. Two roads, same answer, middle hole.
Why the middle hole matters
A belt size is measured to its center hole, which means the size already contains its own tolerance: two holes inward for dress pants that sit higher, two holes outward for thick jeans or a heavy sweater. When you buy the size that fastens on the last hole, you have spent all of that tolerance on day one. The practical test of a well-sized belt is boring and absolute: it fastens on the middle hole over the clothes you wear most. If a belt you love has drifted to its first or last hole, the belt did not change. Buy the next size and donate the argument.
Frequently asked questions
What size belt should I buy for my pant size?
Take your pant waist size and add 2 inches, rounding up to the next even number since belts come in even sizes. A 34 pant takes a 36 belt. The 2 inches are not padding: a belt travels over the waistband, belt loops, and a tucked shirt, and it needs reach beyond the buckle to hit its middle hole.
How is a belt size measured?
From where the leather folds at the buckle pin to the middle hole, not to the tip. That means a size 36 belt is about 36 inches to its center hole and gives you roughly two holes of adjustment in each direction. Cheap belts sometimes measure to the tip instead, which is why an online bargain belt can arrive comically long.
How do I measure my waist for a belt?
Thread a soft measuring tape through your belt loops, or wrap it where you wear your pants, over the clothes you would normally tuck in. Stand naturally. This number is usually 1 to 2 inches bigger than your pant size, which is exactly why the plus-2 rule exists: pant sizes describe the garment before you put a body, a waistband, and a shirt inside it.
What is my belt size in centimeters?
EU belts are sized in centimeters in steps of 5, and the size is the same buckle-to-middle-hole measurement. Multiply your US belt size by 2.54 and take the nearest 5: a US 36 is 91.4 cm, sold as a 90; a US 38 is 96.5 cm, sold as a 95. If you are between EU steps, take the larger one; leather does not grow.
Which belt hole should a belt fasten on?
The middle one, which on a standard five-hole belt is the third. That is the position the size is measured to, and it leaves two holes of slack in each direction for the difference between jeans and dress pants, or between November and January. A belt living on its first or last hole is the wrong size, however good the price was.
Should a braided or no-hole belt be sized differently?
Braided belts fasten anywhere, and ratchet belts adjust in quarter-inch clicks, so sizing is more forgiving, but the same starting number applies: waist measurement or pant size plus 2. Ratchet belts are usually sold as cut-to-fit; cut them to your through-the-loops measurement plus about 6 inches of tail past the buckle.