Watch Strap Size by Wrist Size

Strap width decides whether a strap attaches to your watch. Strap length decides whether it fits your wrist, and it is the number people skip, then discover the strap tail either barely reaches the keeper or flops halfway around their forearm. If you are here for width (20mm, 22mm, and so on), that is the band size chart with lug widths. This page is about length, and the wrist size that drives it.

Strap lengths are written as two numbers, like 115/75mm: the long piece (the tail side with the holes) first, the short piece (the buckle side) second. Total length is the sum, 190mm here, not counting the buckle. Sellers group these into Short, Regular, and Long, and the groups overlap on purpose because case size and tail preference shift the answer.

First: your wrist number

Everything below keys off your wrist circumference measured where the watch sits, snug but not compressed. No tape measure is needed: a paper strip and a ruler gets you within a millimeter or two, and our no-tape method includes a printable true-scale ruler. Round to the nearest quarter inch (6.5, 6.75, 7...) and read the chart.

The strap length chart

These are the standard lengths strap makers actually sell, mapped to wrist circumference. Overlaps are real: a 7.25" wrist sits at the boundary between Regular and Long on every published chart, because a bigger watch case eats strap length and tail taste varies:

Wrist sizeCircumferenceLength categoryCommon sizes sold
5.75-6.5"146-165mmShort105/70mm, 110/70mm
6.0-6.5"152-165mmShort105/70mm
6.5-7.25"165-184mmRegular115/75mm, 120/80mm
7.25-8.0"178-203mmLong125/80mm, 130/85mm
8.0" and up203mm+Extra long140/85mm and longer

The three questions people actually ask

6.5 inch wrist (16.5cm). Short territory. A 105/70mm strap fits with a proper tail; Regular 115/75mm works at 6.75", and many makers list the boundary slightly differently (one puts 6.5-7.0" at 120/70 to 125/75, another at 110/70 to 120/70). That spread is the overlap zone, not a disagreement about physics: at exactly 6.5", buy Short unless you like a long tail.

7 inch wrist (17.8cm). The center of Regular. 115/75mm is cut for you; it is no coincidence that this is the most stocked strap size in existence. 120/80mm gives a little more tail if you wear a larger case.

8 inch wrist (20.3cm). Long. 125/80mm or 130/85mm, and if the strap still barely closes, extra-long ranges (140/85mm and up) exist for exactly this wrist. Some sources put the Long cutoff at 7.5", others at 7.25"; same overlap logic, size to the roomier side when you are on the line.

The arithmetic behind the chart

You can sanity-check any strap against your own numbers, and it is worth doing once because it tells you what a "fit" is:

One worked example, using the cleanest published mapping (115/75mm suits 162.5-182.5mm wrists): a 178mm (7") wrist with a 40mm case sits mid-range, so the middle holes get used and roughly 25mm of tail passes the buckle. The same 7" wrist with a 30mm vintage case sits near the top of the range, uses the last holes, and shows less tail. Both work; neither is wrong.

Strap length vs case size: two different questions

This page answers "will the strap close around my wrist with a sane amount of tail?" Whether the watch head looks right on your wrist is a different question with a different answer: case diameter and especially lug-to-lug versus your wrist width. A 6.5" wrist can be a Regular-length strap wearer and a 36mm-case person at the same time; the two charts are independent. For the head-size question use the case size by wrist size table or the calculator, which draws the actual watch on a wrist your size. And if you wear an Apple Watch, strap length is an S/M vs M/L question instead: see the Apple band size guide. Wear a one-piece NATO? That is its own length system: the NATO strap length guide covers it, and the heavier Zulu strap sizes page covers its big sibling. And if the strap you own is simply too loose or too tight, adjusting a watch band at home is usually a ten-minute job. Sizing a chain or bangle instead of a watch strap? The bracelet measuring guide handles the jewelry side of the same wrist number.

Sources