Shoe sizing & fit glossary

The terms behind every size chart, in plain English. Length systems, fit quirks, and the words that actually decide whether a shoe fits — each defined once, linked to the guides that go deeper.

Foot length

The straight-line distance from the back of the heel to the tip of the longest toe, measured in millimetres. It is the canonical axis every sizing system converts through — get this right and every US/UK/EU/CM number follows.

Last

The three-dimensional foot-shaped form a shoe is built around. The last dictates a shoe's volume, width, heel hold and toe shape, which is why two shoes in the same labelled size can fit completely differently.

Toe box

The front section of the shoe that surrounds the toes. A roomy toe box lets the toes splay; a narrow one (common on performance running and dress shoes) is what people usually feel as a shoe "running small".

Instep

The arched top of the foot between the toes and the ankle. A high instep needs more vertical volume, so high-instep feet often size up or choose a higher-volume last rather than a longer shoe.

Barleycorn

The historic unit behind US and UK sizing: one third of an inch, about 8.5 mm. One full US or UK size equals one barleycorn of length, so a half size is roughly 4.2 mm.

Paris point

The unit behind European sizing: two thirds of a centimetre, about 6.67 mm. One full EU size equals one Paris point, which is why EU sizes step in smaller increments than US sizes.

Mondopoint

A sizing system that states the size directly as foot length in millimetres (or centimetres). Used by Japanese sizing, ski boots, skates and military footwear, it is the most honest system because the number is the measurement.

Brannock Device

The metal foot-measuring tool found in shoe shops. It reads heel-to-toe length, arch length and ball width at once, and its width letters (AAA to EEE) are the basis of the standard width-grade scale.

Width grade

A letter scale describing girth at the ball of the foot, from AAA (very narrow) through D (standard men's) to 2E, 4E and 6E (wide to extra wide). Width is a separate axis from length — see the wide-fit guide.

True to size (TTS)

A shoe that fits at your usual labelled size, with no need to size up or down. In our data this is a fit offset near zero.

Fit offset

How far a brand or model deviates from true to size, expressed in size steps. A negative offset means it runs small (size up); a positive offset means it runs large (size down).

Insole length

The internal length of the footbed — the practical measure of how much room a shoe actually has. It is usually a little longer than the foot it is meant to fit, leaving toe-room ahead of the longest toe.