Bike Size Calculator

Enter your inseam length and select your bike type (road, mountain, or trekking/city) to get a recommended frame size in both centimeters and inches. The Bike Size Calculator uses your body measurements to match you with the right fit — reducing discomfort and improving performance before you even visit a shop.

Select the type of bike you are sizing for.

cm

Stand straight without shoes to measure your height.

cm

Measure from your crotch to the floor while standing flat-footed.

in

Total height in inches (e.g. 5'9" = 69 inches).

in

Measure from your crotch to the floor while standing flat-footed.

Results

Recommended Frame Size

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Frame Size in Inches

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Frame Size Category

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Estimated Saddle Height

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Inseam Used for Calculation

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Frame Size Comparison by Bike Type

Results Table

Frequently Asked Questions

How do I measure my inseam to calculate the right bike frame size?

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.

What bike size do I need?

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.

What's the difference in sizing between road, mountain, and trekking bikes?

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.

What if I'm between two bike sizes?

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.

Can I use my height alone to determine bike size?

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.

What is saddle height and how is it calculated?

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.

Are bike frame sizes measured in centimeters or inches?

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.

Is an online bike size calculator a substitute for a professional bike fit?

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.

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