Bike Size Calculator
Enter your height and inside leg length in centimetres, then choose the type of bike. You get a frame size, a letter size and a saddle height to start from.
- Road, gravel, hybrid and MTB
- Inseam-based sizing
- Saddle height
Sizes vary between brands. Use the result to find the right size on each maker's own chart.
Inseam is a better guide than height. Two riders of the same height can have legs 8 cm apart in length. Frame size controls how high the saddle and top tube sit, so it follows your legs. Height then helps with reach, which is how far forward you stretch to the bars.
Bike size chart
Frame sizes by rider height. Search by your height or a size.
| Height (cm) | Inseam (cm) | Road (cm) | Mountain (in) | Letter |
|---|---|---|---|---|
| 152 to 160 | 70 to 74 | 47 to 50 | 13 to 14 | XS |
| 160 to 168 | 74 to 78 | 50 to 53 | 15 to 16 | S |
| 168 to 176 | 78 to 82 | 53 to 55 | 17 | M |
| 176 to 184 | 82 to 86 | 55 to 57 | 18 to 19 | L |
| 184 to 192 | 86 to 90 | 57 to 60 | 20 to 21 | XL |
| 192 to 200 | 90 to 95 | 60 to 63 | 22 to 23 | XXL |
If you fall between two sizes, the smaller frame is usually easier to adjust for comfort with a longer stem or seatpost. The larger frame suits long legs and a stretched-out position.
Inseam and frame size
Every bike type from one measurement. Slide your inseam to see each frame size.
Road frames are measured along the seat tube in centimetres. Mountain bikes use inches or letter sizes because their seat tubes are short to leave room for dropper posts.
How to measure your inseam
You need a book, a wall and a tape measure. Follow the steps.
Stand against a wall
Back to the wall, feet 15 cm apart, in socks.
Measure in socks with your feet about 15 cm apart, the way you stand over a bike. Take two readings and use the average.
How bike types differ in sizing
The same rider, four different frames. Pick a type.
Measured in centimetres along the seat tube. A racy, stretched position.
Sized like road bikes, often with a taller front end for comfort.
Upright and relaxed for commuting. Slightly smaller than a road frame.
Sized by letter or inches. Reach matters more than seat tube length.
Standover clearance is the space between you and the top tube when you stand over the bike. Mountain bikes need more of it because you step off quickly on rough ground.
Test ride checklist
Numbers get you close. A ride confirms it. Tick these on your test ride.
Tick each item as you go.
Small changes such as stem length, saddle position and bar height can fine-tune fit, but they cannot fix a frame that is two sizes off.
What you get
A starting point for any bike shop. Each tile explains one result.
Centimetres for road and hybrid, inches for MTB.
XS to XXL for brands that use letters.
Inseam × 0.883, measured from the crank axle.
How much clearance to look for.
Whether to size up or down when between sizes.
Saddle height from the centre of the bottom bracket to the top of the saddle is about 0.883 times your inseam. This is the LeMond method and a good starting point for most riders.
Frequently Asked Questions
No question matches that search.
What size bike do I need for my height?
Riders of 170 to 178 cm usually ride a 53 to 56 cm road bike or a medium mountain bike. Inseam narrows it down.
How do I calculate road bike frame size?
Multiply your inseam in centimetres by 0.665. An 83 cm inseam gives a 55 cm frame.
How do I calculate mountain bike frame size?
Multiply your inseam in centimetres by 0.226 for a size in inches. 83 cm gives 18.8 inches, a large.
What saddle height should I use?
Start at inseam × 0.883, measured from the centre of the crank axle to the top of the saddle.
Should I size up or down if between sizes?
Size down for a nimble, upright feel. Size up if you have long legs or prefer a stretched position.
Is a 54 cm frame medium?
Usually, yes. Most brands call 54 to 56 cm a medium road bike.
How much standover clearance do I need?
2 to 5 cm on a road bike and 5 to 10 cm on a mountain bike.
Ride a frame that fits
Measure your inseam carefully, use it with your height to choose a frame size, and set the saddle using the 0.883 rule. Then test ride, adjust the small things and enjoy a bike that feels right from the first mile.
More size calculators
Each one has its own calculator, worked examples and answers to common questions.