How to Measure Your Sit Bones at Home (and Pick a Saddle Width)
Saddle width is the single most important saddle choice, and it depends on one number: the distance between your sit bones. You can measure it at home in five minutes with cardboard and a tape measure. Here is how, and what to do with the result.
Sit on corrugated cardboard on a firm chair, lean slightly forward, press for a few seconds, then measure the distance between the two dents. Add 20 to 30 mm and you have your saddle width. Most people measure 100 to 150 mm.
Rather than guessing, measure your actual position with your own camera.
Check my saddle height and hip rock€5 for one fit, or 10 fits for €25. See pricing →
Why width matters more than padding
Your weight on a bike should rest on your sit bones, the two bony points at the bottom of your pelvis, built to bear load. A saddle narrower than your sit-bone spacing leaves them hanging over the edges, so the soft tissue in between carries the weight instead. That is where numbness and saddle sores come from.
This is why the fashion for soft, wide "comfort" saddles backfires: padding lets the sit bones sink in and the soft tissue takes the pressure anyway. Width is the variable that actually decides comfort; padding is secondary.
Measuring at home
You need a piece of corrugated cardboard, a tape measure and a firm chair or step.
1. Place the cardboard on the chair and sit on it with your feet flat on the floor and your back straight. 2. Lean slightly forward, roughly the angle you ride at, and press down for a few seconds. This is important: the sit bones move closer together as you lean forward, so measure in something like your riding posture, not bolt upright. 3. Stand up. You will see two dents in the cardboard. Mark the centre of each. 4. Measure the distance between the two marks, centre to centre, in millimetres.
Most people fall somewhere between 100 and 150 mm. Repeat it twice to check you get roughly the same number.
Wondering where your own position sits? You can measure it in twelve seconds.
Check my saddle height and hip rock →From measurement to saddle width
The rule most manufacturers use: saddle width equals sit-bone distance plus 20 to 30 mm. So a 120 mm sit-bone measurement points to a saddle around 140 to 150 mm wide.
The extra margin depends on your position. A more upright rider needs more margin because the pelvis sits more open; a low, aggressive rider needs less because the pelvis rotates forward and the effective contact points narrow.
Manufacturers now sell most saddles in two or three widths, typically from 130 to 155 mm, with some women's models up to around 168 mm. Match to your number rather than to the label.
What the shop measurement adds
Many shops measure sit bones with a gel pad or a pressure mat, which is more precise than cardboard and often free. If you have the chance, use it, but the cardboard method gets you within a few millimetres, which is enough to choose between widths.
What width cannot fix
If your saddle is the right width and you still have pain, the problem is almost certainly position: a saddle too high (hips rocking), tilted nose-down, or set too far forward. Width is the foundation, but a correctly-sized saddle at the wrong height still hurts.
That is the order to work in: measure sit bones and get the width right, then check height and tilt. A BikeFit/LAB analysis covers the second half, it measures your knee angle and hip rock so you can see whether your saddle height is the reason a correctly-sized saddle still causes trouble.
FAQ
How do I measure my sit bones at home?
Sit on a piece of corrugated cardboard on a firm chair, lean slightly forward as you would on the bike, press down for a few seconds, then stand up and measure the distance between the two dents centre to centre. Most people measure between 100 and 150 mm.
What saddle width do I need?
Add 20 to 30 mm to your sit-bone distance. A 120 mm measurement points to a saddle around 140 to 150 mm wide. Upright riders need more margin, low aggressive riders slightly less.
Is a wider saddle more comfortable?
Only if it matches your sit bones. Too wide chafes the inner thighs and too narrow puts weight on soft tissue. Width matched to your measurement matters far more than padding.
References
- Lin ZJ, Wang HH, Chen CH (2023). The effect of bicycle saddle widths on saddle pressure in female cyclists. Journal of Sports Science and Medicine, 22(3):425–430. doi:10.52082/jssm.2023.425
General position guidance, not medical advice. Individual anatomy varies; consult a physician or professional fitter for persistent pain. How BikeFit/LAB measures, and where its reference ranges come from · How accurate is an AI bike fit?
Rather than guessing, measure your actual position with your own camera.
Check my saddle height and hip rock€5 for one fit, or 10 fits for €25. See pricing →