How to measure your inseam for a bike
One book, one wall, one tape measure. Sixty seconds to a better fit.
Short answer: stand barefoot against a wall, pull a book up snugly between your legs like a saddle, mark the top edge on the wall and measure from the mark to the floor.[1 2 · Oct 29, 2026]
Step by step
- Shoes off. Take off your shoes and stand with your back against a wall, feet about 20 cm (8 in) apart.[2 · Oct 29, 2026]
- Book up. Hold a hardcover book level between your legs and pull it up snugly, the way a saddle would sit.[1 · Oct 29, 2026]
- Mark it. Mark the wall at the top edge of the book.[1 · Oct 29, 2026]
- Measure. Measure from the mark straight down to the floor.[1 2 · Oct 29, 2026] Do it twice and use the average.
For kids, the same method works, and the inside leg measurement is a good guide to standover height on young riders.[1 · Oct 29, 2026]
What to do with your inseam
- Kids: compare it with the minimum inseam for each wheel size in the kids bike size chart. For example, one guide lists a 16 in minimum inseam for 16-inch wheels and 20 in for 20-inch wheels.[1 · Oct 29, 2026]
- Adults: compare it with the inseam column on the model's own size chart, where one is given, to choose between two sizes.
- A frame-size cross-check: one city and e-bike maker says inseam × 0.68 gives your frame size in cm for its bikes (take 4 cm off the inseam first for a suspension seatpost).[2 · Oct 29, 2026]
Inseam × 0.68 lookup (one maker's rule)
| Inseam | Frame size by that rule[2 · Oct 29, 2026] |
|---|---|
| 70 cm (27.6 in) | 47.6 cm |
| 72 cm (28.3 in) | 49.0 cm |
| 74 cm (29.1 in) | 50.3 cm |
| 76 cm (29.9 in) | 51.7 cm |
| 78 cm (30.7 in) | 53.0 cm |
| 80 cm (31.5 in) | 54.4 cm |
| 82 cm (32.3 in) | 55.8 cm |
| 84 cm (33.1 in) | 57.1 cm |
| 86 cm (33.9 in) | 58.5 cm |
| 88 cm (34.6 in) | 59.8 cm |
| 90 cm (35.4 in) | 61.2 cm |
Our arithmetic from the maker's 0.68 rule. It applies to that maker's frames, which are measured from the center of the bottom bracket to the top of the seat tube; road and mountain brands label sizes differently, so always use the model's own chart.[2 3 · Oct 29, 2026]
Measure your height the same way
Stand barefoot with your back against the wall, feet a little less than shoulder-width apart, and record your height.[4 · Oct 29, 2026]
Sources: 1. BikeRadar, Bike sizes for kids. 2. Gazelle, Bike frame size chart. 3. BikeRadar, Road bike sizing. 4. Polygon Bikes, Sizing guide (height charts by bike type). Checked Oct 29, 2026. Trademarks belong to their owners; charts are restated in our own tables, not reproduced.