Enter your inseam and crank length to see where three published formulas put your saddle. Then check it the way bike fitters do: by the angle of your knee with the pedal at the bottom, measured on a photo.
Measured barefoot, floor to crotch. How to measure it is below the calculator.
Sit on the bike with the crank pointing down, in line with the seat tube. Take a photo from the side and tap your hip, knee and ankle.
Your photo is measured in your browser and never uploaded.
This is the protocol used in the saddle height studies by Peveler and colleagues, who used a board where you use a book. A few millimetres of error in the inseam become the same few millimetres in the saddle.
Greg LeMond multiplies your inseam by 0.883 and measures from the centre of the bottom bracket to the top of the saddle. Hamley and Thomas used 109% of inseam, measured from the pedal axle to the top of the saddle with the crank in line with the seat tube. Ferrer-Roca and colleagues, filming riders as they pedalled, proposed 108.6% to 110.4% measured the same way.
The difference that matters is the crank. LeMond measures from the bottom bracket, so his number does not change with crank length; the other two measure from the pedal, so they do. The calculator converts all three to one measurement, bottom bracket to the top of the saddle, so you can hold a tape measure against your own bike.
None of them is exact for one person. In a study of 19 trained riders, the LeMond formula produced knee angles from 14° to 43°. In two others, the 109% method left the knee outside the 25° to 35° range in 63% of 27 riders and 73% of 11. A formula gets you close. Your knee tells you whether you are there.
Bike fitters judge saddle height by the knee. With the pedal at the bottom and the crank in line with the seat tube, the knee should stay bent: usually between 25° and 35° with the rider sitting still. The range comes from Holmes and colleagues, who gave narrower targets for riders with knee problems: 25° for pain at the kneecap, 25° to 30° for quadriceps tendon problems and 30° to 35° for pain on the outside of the knee (the iliotibial band).
While you pedal, the knee straightens a few degrees more than when you sit still, between 5° and 8° more in one study. That is why the target measured on video is higher: 30° to 40°, from Ferrer-Roca and colleagues. The calculator uses the right range for each kind of photo.
A knee straighter than the range means the saddle is high. A knee more bent means it is low.
A photo is a flat, two-dimensional measurement. If the camera is not square to your leg the angle reads wrong, and a study of two-dimensional video found it reads the knee about 2° straighter than 3D motion capture. Treat a result within a couple of degrees of the edge of the range as borderline.
If you change crank length, move the saddle the same amount the other way: 5 mm shorter cranks, 5 mm higher saddle. That keeps the distance from saddle to pedal at the bottom of the stroke the same, which is how researchers set riders up when they compare crank lengths. The crank length calculator shows what else changes.
Shoes, cleats and pedals also change the distance from your foot to the pedal axle, and none of the formulas includes them. That is one more reason to check your knee angle on your own bike rather than trust a number.
The photo is opened by this page in your browser and drawn on your screen. It is never uploaded, and the three points you tap are measured in the page itself.
Saddle height is one setting among several. Saddle setback, reach, handlebar height and cleat position all change how your knee moves, and a fitter watches you pedal.
The ranges come from groups of riders. Flexibility, leg length differences and old injuries move your own best height. If a knee or hip hurts, see a physiotherapist or a fitter before you move anything.
A camera that is not square to your leg, or a point tapped a centimetre off, changes the result by several degrees.
High enough that your knee stays slightly bent, about 25° to 35°, with the pedal at the bottom and you sitting still. As a starting point, multiply your inseam by 0.883 and measure from the centre of the bottom bracket to the top of the saddle. Then check your knee angle.
It is a good starting point and a poor final answer. In a study of 19 trained riders it produced knee angles from 14° to 43°, and it does not change with crank length. Check the result against your knee angle.
Hamley and Thomas set saddle height at 109% of inseam, measured from the pedal axle to the top of the saddle with the crank in line with the seat tube. Later studies found it left the knee outside 25° to 35° in most riders they tested.
From the centre of the bottom bracket axle, along the seat tube, to the top of the saddle where you sit. The calculator gives every method in that measurement.
No. Every method here aims for a bent knee at the bottom: 25° to 35° sitting still, or 30° to 40° while pedalling. A straight leg means the saddle is too high.
Yes, by the same amount in the other direction: 5 mm shorter cranks, 5 mm higher saddle, measured from the bottom bracket. The distance to the pedal at the bottom of the stroke stays the same.
No. It is opened and measured in your browser and never leaves your device.
