F·01 · Sport and sizing
Bike size calculator by height
This bike size calculator gives you the frame size for your height: road, gravel, mountain and kids bikes, with the measurement and the letter size.
The seat tube in yellow is what the frame size measures. Your height is on the right. Schematic drawing.
What to buy
At 172 cm: M · 54 cm
To buy
- 1Road bike, size M (54 cm)
Estimate only: always go by what the product label says.
Link copied
Estimate only: always go by what the product label says.
What size bike do I need?
Height is the starting point. BikeRadar's charts match each height band to a frame size: in centimetres for road bikes, in inches for mountain bikes. The number is the length of the seat tube, the one under the saddle. Most brands now also give letter sizes (S, M, L), and the calculator shows both.
If your height is within 2 cm (about 3/4 in) of a size change, the calculator tells you: that is when it pays to try both sizes.
A worked example
In feet and inches (US). The calculator opens with a rider 5 ft 8 in tall (173 cm).
- 173 cm falls in the 170-178 cm band
- Road bike: 54 cm frame, size M
- Mountain bike: 18 inch frame, size M
Road and gravel bike size chart
| Height | Frame |
|---|---|
| 5 ft 1 in - 5 ft 4 in (155-163 cm) | 48 cm |
| 5 ft 4 in - 5 ft 7 in (163-170 cm) | 51 cm |
| 5 ft 7 in - 5 ft 10 in (170-178 cm) | 54 cm |
| 5 ft 10 in - 6 ft (178-183 cm) | 56 cm |
| 6 ft - 6 ft 3 in (183-191 cm) | 58 cm |
| 6 ft 3 in - 6 ft 5 in (191-196 cm) | 60 cm |
By letter, again from BikeRadar: XS from 152 to 160 cm, S from 160 to 168, M from 168 to 175, L from 175 to 183, XL from 183 to 191, XXL from 191 to 198.
Mountain bike and kids bike sizes
| Height | MTB frame |
|---|---|
| 5 ft 1 in - 5 ft 4 in (155-163 cm) | 15" |
| 5 ft 4 in - 5 ft 7 in (163-170 cm) | 16" |
| 5 ft 7 in - 5 ft 10 in (170-178 cm) | 18" |
| 5 ft 10 in - 6 ft (178-183 cm) | 19" |
| 6 ft - 6 ft 3 in (183-191 cm) | 20" |
By letter: XS from 152 to 162 cm, S from 162 to 170, M from 170 to 178, L from 178 to 185, XL from 185 up.
Kids bikes go by wheel size: 16 inch from about 104 cm (3 ft 5 in), 20 inch from 120 cm (3 ft 11 in), 24 inch from 127 cm (4 ft 2 in), 26 inch from 140 cm (4 ft 7 in). Avoid buying a size up to grow into: a bike that is too big is hard to control.
Common mistakes
- Trusting the letter alone. One brand's M can be another's S: always check the maker's chart.
- Measuring with shoes on. Take your height barefoot, against a wall.
- Going bigger when you are between sizes. The smaller size is sportier and more compact, the larger one more stretched out: try both if you can.
- Forgetting the adjustments. Saddle height, seatpost and stem move a few centimetres; the frame does not.
Sources
Last reviewed: October 8, 2026 · About us