Bike Size Calculator

Stand barefoot with your back against a wall and place a book or ruler between your legs, pressing it up to your crotch as a bike saddle would. Measure the distance from the top of the book to the floor — that's your inseam. Repeat the measurement a couple of times for accuracy.

Your ideal bike frame size depends primarily on your inseam length. For a road bike, multiply your inseam in cm by 0.67. For a trekking or city bike, multiply by 0.64. Mountain bike frames run about 10–11 cm smaller than road bike sizes for the same rider. Use this calculator to get an instant recommendation based on your measurements.

Road bikes use the largest frames for a given inseam because they prioritize an aggressive, stretched-out position. Trekking and city bikes use slightly smaller frames (inseam × 0.64) for a more upright, comfortable posture. Mountain bikes have the smallest frames — typically 10–11 cm smaller than road equivalents — to allow greater standover clearance for technical terrain.

If you fall between two frame sizes, consider your riding style. If you prefer a more aggressive, performance-oriented position, go with the larger frame. If you prioritize comfort and upright riding, choose the smaller size. A professional bike fit at a local shop can also help you decide, as stem length and seat post adjustments can fine-tune fit across a range.

Height alone gives a rough approximation, but inseam length is a more reliable measurement since it directly relates to your leg length and pedaling reach. Two people of the same height can have very different inseam lengths, leading to significantly different frame size recommendations. Always measure your inseam for the most accurate result.

Saddle height is the distance from the center of the bottom bracket (pedal axle) to the top of the saddle. A commonly used formula multiplies your inseam length by 0.883. Setting the correct saddle height is critical — too high causes hip rocking and knee strain, while too low reduces power and can cause knee pain.

Road and trekking bike frames are traditionally measured in centimeters (e.g. 54 cm, 56 cm), while mountain bike frames are often labeled in inches (e.g. S, M, L) or sometimes in both. This calculator provides your recommended size in both centimeters and inches, along with a size category label for convenience.

No — an online calculator gives you a solid starting point, but it can't account for individual proportions like arm length, torso length, flexibility, or riding goals. A professional bike fit from a certified fitter uses these additional variables to optimize your position for comfort and performance. Use this calculator to narrow down frame choices before heading to a shop.