Bike Size Calculator — Frame Size from Inseam & Height
Enter your inseam length and body height, select your bike type, and get an estimated frame size in centimetres and inches, a size category (XS–XXL) and a starting saddle height using the LeMond method.
Bike type
cm
cm
M — 21.1" — Road bike
- 1
Saddle height (LeMond)
80 × 0.883 = 70.6Starting saddle height from pedal spindle to saddle top along the seat tube. - 2
Recommended frame size
80 × 0.67 = 53.6Inseam multiplier for Road bike (0.67).
How does this calculator work?
Road bike frame size ≈ inseam × 0.67; mountain bike ≈ inseam × 0.59; city bike ≈ inseam × 0.64. Saddle height ≈ inseam × 0.883 (LeMond formula). These multipliers are standard estimates — individual anatomy, riding style and brand sizing variation mean a test ride and professional fit are always recommended.
Formula
How this is calculated
Frame size recommendations are based on inseam length rather than total height because leg length is the primary constraint: the rider must be able to straddle the top tube and have a comfortable pedalling reach. The most widely used road-bike formula (attributed to Greg LeMond) multiplies inseam in centimetres by 0.67 to give the seat-tube length — the standard frame measurement for road bikes. Mountain bike frames are measured to the top of the seat tube, and riders are expected to have several centimetres of standover clearance, so the factor is lower (0.59). City and hybrid bikes sit between the two at roughly 0.64.
These multipliers are editable estimates based on generalised fitting guidelines (as of 2025). Real-world frame choice also depends on riding position preference, arm length, torso length and personal comfort — a professional bike fit will always give a more precise result. Use this calculator as a starting point to narrow down which sizes to test-ride.
Saddle height uses the LeMond formula: 0.883 × inseam, measured from the centre of the bottom bracket to the top of the saddle along the seat tube. This is a commonly recommended starting point; micro-adjustments for knee comfort and pedalling style are made after test rides.
Frequently asked questions
Stand in flat cycling shoes (or bare feet, then add ~1 cm for shoes) with your back against a wall. Place a hardcover book between your legs as if it were a saddle, hold it level and firmly against your crotch, and measure from the floor to the top of the book. This is your cycling inseam.
No — sizing varies significantly between manufacturers. A "Medium" from one brand may correspond to a "Large" from another, and the same numerical frame size can feel different depending on geometry (stack, reach, top-tube length). Always check the specific brand's size chart and, if possible, test-ride the bike.
Multiply your inseam in centimetres by 0.883. The result is the distance from the centre of the bottom bracket to the top of the saddle, measured along the seat tube. This is a well-established starting point; adjust by ±5 mm based on knee comfort after a few rides.
Also known as
TG we-Calculate Editorial Team. (2026). Bike Size Calculator — Frame Size from Inseam & Height [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/bike-size-calculator
TG we-Calculate Editorial Team. "Bike Size Calculator — Frame Size from Inseam & Height." TG we-Calculate. 2026. https://we-calculate.com/calculator/bike-size-calculator.
TG we-Calculate Editorial Team, "Bike Size Calculator — Frame Size from Inseam & Height," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/bike-size-calculator
@misc{wecalculate_bike_size_calculator, title = {Bike Size Calculator — Frame Size from Inseam & Height}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/bike-size-calculator}}, year = {2026}, note = {TG we-Calculate} }
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