Bike Size Calculator

The right size bike is more comfortable, easier to control and safer. Enter your height and inside leg (inseam), pick the type of bike, and the calculator gives a starting frame size and the usual S/M/L size. For children it gives the wheel size instead. Always test ride if you can, since every brand sizes a little differently.

Rider

Height

Inseam (inside leg)

Stand against a wall in socks with a book pressed up between your legs; measure floor to the top of the book.

Bike type

Frame size to try

Bike type	Size

How it works

Road / gravel frame (cm) = inseam cm × 0.70
Mountain frame (inches) = inseam cm × 0.226
Hybrid / city frame (cm) = inseam cm × 0.685
S/M/L by height: XS under 160 cm, S 160-168, M 168-178, L 178-186, XL 186-194, XXL over 194
Kids by height: 12 in wheels 85-100 cm, 14 in 95-110, 16 in 105-120, 20 in 115-135, 24 in 130-150, 26 in / small adult above

Three things this tool can't see

Brand differences. Frame sizes are measured differently by each maker. Use their size chart too.
Your body. Long legs or a long body can move you up or down a size. A test ride tells you most.
Fit details. Saddle height, stem length and handlebar height can all be adjusted for comfort.

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This tool gives general information only and is not medical or nutrition advice. Check with a doctor before starting exercise or changing your diet. We make no health or performance claims. Some links on this site may earn us a commission. Read our disclosure.