Saddle height calculator
Enter your inside leg and get a starting saddle height in seconds. A saddle that is too low or too high costs power and is the most common cause of knee pain on the bike.
Usually stamped on the back of the crank arm, near the pedal.
Enter your inside leg to see your saddle height.
Measure your inside leg
- Wear cycling shorts, leggings or close-fitting underwear. Take your shoes off and stand with your back against a wall, feet about 15 cm apart.
- Push a hardback book between your legs, spine up, and pull it up firmly into your crotch, as a saddle would sit.
- Keep the book level and mark the top of the spine on the wall. Step away and measure from the floor to the mark. That is your inside leg.
Take care with this one: everything is worked out from it, and each 1 cm of inside leg moves the saddle by about 9 mm. Measure two or three times and use the average. A second person helps.
Measure and set your saddle
- Find the centre of the bottom bracket: the middle of the axle the cranks turn on.
- Measure in a straight line from there, up along the seat tube, to the top of the saddle where you sit.
- To change it, loosen the seatpost clamp, move the saddle and tighten it again to the torque printed on the clamp. A strip of tape on the seatpost marks where you started.
Fine-tune it on the bike
A formula gets most people close, not exact. Leg proportions, feet, shoes and pedals all differ. Use one of these checks after setting the height.
Knee bend check
Ask someone to take a side-on photo while you pedal, with the crank pointing down. Your knee should be bent by 25 to 35 degrees. Less bend means the saddle is too high, more means too low.
Heel check
In your riding shoes, put your heels on the pedals and pedal backwards slowly. Your leg should just straighten at the bottom. If your hips rock, the saddle is too high. If your knee stays bent, it is too low.
- Too high: hips rock on the saddle, toes point down to reach the pedal, pain behind the knee.
- Too low: you feel cramped, pedalling feels heavy, pain at the front of the knee.
- Triathlon and TT bikes: start from the same number, then do the knee bend check in your aero position, since a forward saddle changes how the leg extends.
How this is worked out
The main figure uses the LeMond formula: inside leg x 0.883, less 3 mm for clip-in pedals, gives the distance from the bottom bracket to the top of the saddle. When three riders were each fitted by nine professional bike fitters, this formula landed within 1 mm of the fitters' average (Braeckevelt and others, 2019). With flat pedals, add those 3 mm back. As a second opinion we use the Hamley formula: 109% of inside leg from the pedal axle to the top of the saddle, less the crank length. A 2005 study comparing the two in trained cyclists found no real difference between them, and the range shows where both land for you.
The LeMond formula does not say which cranks it assumes, so we take 172.5 mm and move the saddle up 1 mm for every 1 mm shorter crank, and down for longer ones. Moving in steps of 5 mm at most is common bike fitting advice. These are our own assumptions. If you have pain that does not go away, see a professional bike fitter.