Bike Frame Size Calculator
Estimate road, gravel or mountain bike frame size from height and inseam, with saddle-height, reach and stack starting points.
Height helps sanity-check proportions; the final fit pick is driven mostly by inseam.
Measure barefoot from the floor to the top of a book held level against the saddle-contact point.
Size chart for Road
| Size | Seat tube, cm |
|---|---|
| XXS | 47 cm |
| XS | 50 cm |
| S | 52 cm |
| M | 54 cm |
| L | 56 cm |
| XL | 58 cm |
| XXL | 61 cm |
If you are between sizes, the smaller frame usually feels more aggressive and agile, while the larger frame may feel calmer and more upright. Final choice should come after a test ride or fit check.
Estimate a starting bike size
English bike-size intent expects a practical starting frame size from height, inseam and bike type, with a clear caveat that brand geometry and test rides matter.
Fit still depends on the bike
- Road, gravel and mountain bikes use different size conventions.
- Reach, stack, stem length, saddle position and handlebar width can change fit.
- If you are between sizes, check the manufacturer's chart and test ride when possible.
Frequently Asked Questions
Sources and References
Calculations are based on the listed reference sources. Links open in a new tab.
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