Bike Size Calculator — Find Your Perfect Frame
With this bike size calculator, you can estimate the bike size of your new bike in the blink of an eye. Just choose the type of bike — road, mountain, or general-purpose city/trekking bike, input your height and inseam, and we will recommend some bike frame sizes for you to take into consideration. With our tool, you can also find a perfect bike fit for your child.
Coronatimes — when bikes became the new toilet paper
At the beginning of the pandemic, people were hoarding toilet paper, and then bike sales boomed. With public transport services heavily reduced and the risk of having people in close proximity, many of us chose cycling as an alternative way of commuting. Also, many ride bikes to preserve their mental and physical health while observing social distancing. We know that any amount of activity can work wonders, especially in hard times.
Even if you were not into pedaling before the pandemic, it's probable that the time has finally come — you need to buy a bike. But how do you choose one if you last cycled many years ago or never at all? As a lot of shopping has shifted to the internet, you'll likely have no option of testing the bike before you buy it. This is where we come in handy.
Types of Bikes
- Road Bikes — Lightweight frames optimized for speed on paved roads. Drop handlebars, thin tires. Frame size is measured in centimeters (cm).
- Mountain Bikes — Robust frames built for off-road trails. Wider tires and front (or full) suspension. Frame size is measured in inches.
- City / Trekking Bikes — Versatile bikes for everyday commuting and leisure riding on mixed terrain. Comfortable upright position.
How to Calculate a Bike Size? Measure Your Inseam!
The most reliable way to find your frame size is based on your inseam measurement — the distance from your crotch to the floor. Here's how to measure it:
- Stand with your back against a wall, feet about 15–20 cm (6 inches) apart.
- Place a book or ruler between your legs, pressing it firmly upward as a saddle would.
- Measure from the top of the book to the floor.
- That measurement is your inseam length.
Once you have your inseam, our calculator applies the standard industry formulas:
- Road bike: Frame (cm) = Inseam (cm) × 0.67
- Mountain bike: Frame (in) = Inseam (in) × 0.66
- City/Trekking bike: Frame (cm) = Inseam (cm) × 0.685
What Bike Size Do I Need?
Bike size varies by type. Road bikes use centimeters, while mountain bikes typically use inches or S/M/L labels. Our calculator handles all three types and recommends a frame size and size category (XS through XXL) based on your measurements.
Bike Frame Size Chart
| Size | Frame (cm) | Frame (in) | Rider Height | Inseam |
|---|---|---|---|---|
| XS | < 48 cm | < 19" | < 161 cm / < 5'3" | < 72 cm / < 28" |
| S | 48–52 cm | 19–20.5" | 161–168 cm / 5'3"–5'6" | 72–78 cm / 28–31" |
| M | 52–56 cm | 20.5–22" | 168–175 cm / 5'6"–5'9" | 78–84 cm / 31–33" |
| L | 56–58 cm | 22–23" | 175–183 cm / 5'9"–6'0" | 84–87 cm / 33–34" |
| XL | 58–61 cm | 23–24" | 183–188 cm / 6'0"–6'2" | 87–91 cm / 34–36" |
| XXL | 61+ cm | 24+" | 188+ cm / 6'2"+ | 91+ cm / 36+" |
| Size | Frame (in) | Frame (cm) | Rider Height | Inseam |
|---|---|---|---|---|
| XS | < 14" | < 36 cm | < 161 cm / < 5'3" | < 72 cm / < 28" |
| S | 14–16" | 36–41 cm | 161–168 cm / 5'3"–5'6" | 72–78 cm / 28–31" |
| M | 16–18" | 41–46 cm | 168–175 cm / 5'6"–5'9" | 78–84 cm / 31–33" |
| L | 18–20" | 46–51 cm | 175–183 cm / 5'9"–6'0" | 84–87 cm / 33–34" |
| XL | 20–22" | 51–56 cm | 183–190 cm / 6'0"–6'3" | 87–92 cm / 34–36" |
| XXL | 22+" | 56+ cm | 190+ cm / 6'3"+ | 92+ cm / 36+" |
Different Sizes for Different Purposes
Choosing a bike isn't just about frame size. Consider what you'll use it for:
- Speed & fitness → Road bike with a proper fit (aerodynamic position)
- Off-road adventures → Mountain bike sized to allow good standover clearance
- Daily commuting → City/trekking bike with upright posture for comfort
- Children → Size by wheel diameter (12", 16", 20", 24") rather than frame size
Don't Try to Fit Your Bike — Make Your Bike Fit You
Frame size is just the starting point. After you find the right size, a professional bike fitting adjusts saddle height, saddle fore-aft position, handlebar height, and stem length to your body geometry. A proper fit reduces injury risk and improves performance.
Quick standover check: When you straddle the bike (both feet flat on the ground), there should be 2–5 cm (1–2 inches) of clearance between you and the top tube for road bikes, and 5–10 cm (2–4 inches) for mountain bikes.
Tips for Buying a Bike
- Test ride whenever possible — even one lap around a parking lot tells you a lot.
- Check the standover height — you should be able to stand flat-footed with the frame between your legs.
- Consider an adjustable seatpost — small adjustments can make a big difference in comfort.
- Go half a size up if you prefer a more upright, comfortable position; half a size down for a more aggressive, aero position.
- Buy from a reputable bike shop where staff can help you fine-tune the fit.
Frequently Asked Questions
- Can I use this calculator for kids' bikes?
- Kids' bikes are sized by wheel diameter (12", 16", 20", 24", 26"), not frame size. Enter your child's measurements for a rough guide, but look up wheel-size charts specific to children.
- Road bike vs mountain bike size — are they the same?
- No. Road bikes are measured in centimeters; mountain bikes in inches. The formulas are also slightly different, so always specify the bike type in our calculator.
- What if I'm between two sizes?
- Choose the smaller size if you prefer a more responsive, sportier feel; choose the larger size if you want more comfort and a more upright position.
- How accurate is the inseam formula?
- The formula gives a solid starting point. Factors like arm length, torso length, flexibility, and riding style can shift the ideal frame size by one category. A professional fit is always recommended for serious cyclists.
- After buying a bike, what's next?
- Check out our Calories Burned Biking Calculator to see how much energy you use on your new ride!