What is a Brannock Device?
That flat metal tool with sliders that a shoe-store employee places your foot on is a Brannock Device — the industry-standard foot measurer since the 1920s. The clever part: it measures three things, not one.
The three measurements it takes
- Heel-to-toe length. The overall length of your foot, from the heel cup to your longest toe. This sets the baseline size.
- Heel-to-ball (arch) length. The distance from your heel to the ball of your foot, where the foot flexes. The device sizes you on whichever is longer — toe length or arch length.
- Width. A side slider reads your width and reports it as a letter (B, D, 2E, and so on) for that length.
Why arch length can change your size
A shoe bends where your foot bends — at the ball. If your heel-to-ball measurement is long relative to your toes, the Brannock Device bumps you up a size so the shoe’s flex point sits under your joint, not behind it. That’s why an in-store fitting occasionally gives you a different number than the one you expect, even though nothing is wrong with your feet.
Getting the same result at home
You don’t need the metal tool. For most people, the heel-to-longest-toe length is enough to find the right size — the arch adjustment mainly matters at the extremes. Measure your foot length in centimetres against a wall, take the larger foot, and convert that number to your size in any brand.
Follow our step-by-step guide to measuring your shoe size, then drop the centimetre value into the converter to get your size in the brand you’re buying. Curious why the number differs by brand? See why shoe sizes differ between brands.
Frequently asked questions
What does a Brannock Device measure?
Three things: overall heel-to-toe length, heel-to-ball (arch) length, and foot width. The size it gives you is based on the longer of the length and arch readings, which is why a salesperson sometimes sizes you differently from your usual number.
Why does it measure arch length as well as foot length?
Your shoe needs to flex where your foot flexes — at the ball, not the toes. If your heel-to-ball length is longer than average for your toe length, the device sizes you up so the shoe’s flex point lines up with yours.
Can I measure my shoe size without a Brannock Device?
Yes. For most people, measuring heel-to-longest-toe length in centimetres at home is enough to find the right size. Use a wall, paper and a ruler, then convert that length to your size in any brand.
Should I measure both feet?
Always. It is normal for one foot to be larger, so measure both and size to the bigger one. The Brannock Device is used on each foot for the same reason.