Choose a bike, then confirm the size
Start with bike selection and sizing, then use geometry, equipment, drivetrain, tire, and performance tools when the decision needs more detail. Every calculator is free and works without signup.
34 practical tools
100% free tools
Most Popular Calculators
· Based on rider usageBike Finder Quiz10-question quiz that recommends your ideal bike type, frame size, and matching brands. Ideal first stop if you don't yet know whether you want a road, gravel, mountain, hybrid, or e-bike.PopularBike Sizing
General Bike Size CalculatorUniversal bike sizing tool for road bikes, mountain bikes, and hybrid bicycles. Uses height and inseam measurements for accurate frame size recommendations.PopularBike SizingKids Bike Size CalculatorAge and height-based sizing specifically designed for children's bikes. Accounts for growth and development to ensure safety and comfort.PopularBike SizingRoad Bike Size CalculatorPerformance-focused sizing for speed and efficiency on pavement. Optimized for aerodynamics and power transfer.PopularBike SizingSaddle Height CalculatorCalculate optimal saddle height using multiple professional methods including 109%, Hamley, and LeMond formulas for perfect pedaling efficiency.PopularBike FitTire Pressure CalculatorGet perfect front and rear tire pressure based on rider weight, tire width, terrain type, and tube setup. Optimized for comfort and performance.PopularWheels & Tires
General Bike Size CalculatorUniversal bike sizing tool for road bikes, mountain bikes, and hybrid bicycles. Uses height and inseam measurements for accurate frame size recommendations.PopularBike SizingKids Bike Size CalculatorAge and height-based sizing specifically designed for children's bikes. Accounts for growth and development to ensure safety and comfort.PopularBike SizingRoad Bike Size CalculatorPerformance-focused sizing for speed and efficiency on pavement. Optimized for aerodynamics and power transfer.PopularBike SizingSaddle Height CalculatorCalculate optimal saddle height using multiple professional methods including 109%, Hamley, and LeMond formulas for perfect pedaling efficiency.PopularBike FitTire Pressure CalculatorGet perfect front and rear tire pressure based on rider weight, tire width, terrain type, and tube setup. Optimized for comfort and performance.PopularWheels & TiresBike Sizing9 tools
Find the right frame size for any bike type, age, or discipline.
Bike Finder Quiz10-question quiz that recommends your ideal bike type, frame size, and matching brands. Ideal first stop if you don't yet know whether you want a road, gravel, mountain, hybrid, or e-bike.PopularGeneral Bike Size CalculatorUniversal bike sizing tool for road bikes, mountain bikes, and hybrid bicycles. Uses height and inseam measurements for accurate frame size recommendations.PopularKids Bike Size CalculatorAge and height-based sizing specifically designed for children's bikes. Accounts for growth and development to ensure safety and comfort.PopularMountain Bike Size CalculatorTrail-optimized sizing with proper standover clearance and geometry for off-road riding. Perfect for XC, trail, and enduro bikes.Road Bike Size CalculatorPerformance-focused sizing for speed and efficiency on pavement. Optimized for aerodynamics and power transfer.PopularGravel Bike Size CalculatorSpecialized sizing for gravel bikes accounting for riding style, terrain preference, and the unique geometry of gravel frames.E-Bike Size CalculatorSize your electric bike correctly considering motor type, battery placement, frame style options including step-through designs.BMX Bike Size CalculatorFind the right BMX bike size for race, freestyle, street, or park riding. Uses height and age to recommend top tube length and wheel size.Triathlon Bike Size CalculatorTriathlon and time trial bike sizing using height, inseam, torso, and arm length. Includes stack/reach targets and race distance adjustments.
General Bike Size CalculatorUniversal bike sizing tool for road bikes, mountain bikes, and hybrid bicycles. Uses height and inseam measurements for accurate frame size recommendations.PopularKids Bike Size CalculatorAge and height-based sizing specifically designed for children's bikes. Accounts for growth and development to ensure safety and comfort.PopularMountain Bike Size CalculatorTrail-optimized sizing with proper standover clearance and geometry for off-road riding. Perfect for XC, trail, and enduro bikes.Road Bike Size CalculatorPerformance-focused sizing for speed and efficiency on pavement. Optimized for aerodynamics and power transfer.PopularGravel Bike Size CalculatorSpecialized sizing for gravel bikes accounting for riding style, terrain preference, and the unique geometry of gravel frames.E-Bike Size CalculatorSize your electric bike correctly considering motor type, battery placement, frame style options including step-through designs.BMX Bike Size CalculatorFind the right BMX bike size for race, freestyle, street, or park riding. Uses height and age to recommend top tube length and wheel size.Triathlon Bike Size CalculatorTriathlon and time trial bike sizing using height, inseam, torso, and arm length. Includes stack/reach targets and race distance adjustments.Bike Fit10 tools
Dial in saddle, stem, bars, and contact points for comfort and power.
Saddle Size CalculatorCalculate perfect saddle width based on sit bone measurements. Prevents discomfort and improves cycling performance.Saddle Height CalculatorCalculate optimal saddle height using multiple professional methods including 109%, Hamley, and LeMond formulas for perfect pedaling efficiency.PopularStem Length CalculatorDetermine optimal stem length for perfect reach and bike handling. Balances comfort and control for any riding style.Handlebar Width CalculatorFind a starting bar width from shoulder measurement, then check an MTB trail range, trim limits, and cockpit compatibility.Reach & Stack CalculatorCalculate a practical frame reach and stack range from body measurements. Compare your proportions against common frame sizes.Stem Comparison CalculatorCompare two stem, spacer, and angle setups side by side to see exactly how your handlebar reach and height change before buying parts or flipping a stem.Helmet Fit CheckerCheck helmet fit from head circumference: candidate sizes that cover your measurement, riding-use matching, and the physical strap and stability checks.Saddle Width CalculatorTurn sit-bone width into a target saddle width in mm, plus the closest stocked widths from Specialized, Bontrager, Fizik, Selle Italia, and Ergon.Cycling Glove Size CalculatorConvert hand circumference to cycling-glove size. Adult and youth ranges with road vs MTB fit notes.Cycling Lens SelectorAnswer nine questions about how and where you ride to get a lens feature shortlist - tint family, polarization, anti-fog, and prescription approach. No VLT numbers or product picks.
Drivetrain5 tools
Plan gears, cranks, chain length, and cadence for every ride profile.
Gear Ratio CalculatorCalculate and compare gear ratios for any chainring and cassette combination. Compare 1x vs 2x drivetrains, view gear inches, and find overlapping gears.Crank Length CalculatorDetermine optimal crank arm length based on inseam measurement and riding discipline. Supports road, mountain, track, and triathlon setups.Chain Length CalculatorCalculate the correct chain length using the Shimano method. Input chainstay length and drivetrain sizes to get exact link count.Speed & Cadence CalculatorCalculate cycling speed from gear ratio and cadence, or find the cadence needed for a target speed. Visualize speed across the full RPM range.Skid Patch CalculatorCalculate skid patches for fixed-gear bikes. Find the best gear combinations for maximum tire life with both single-leg and ambidextrous skidding.
Wheels & Tires4 tools
Pick the right tires, pressure, spokes, and rim sizes for your setup.
Wheel & Tire Size CalculatorCalculate total wheel diameter for any rim and tire combination. Convert between ETRTO, French, and imperial tire size formats.Spoke Length CalculatorCalculate spoke lengths for wheel building based on hub and rim measurements. Includes common hub presets and cross pattern selection.Tire Pressure CalculatorGet perfect front and rear tire pressure based on rider weight, tire width, terrain type, and tube setup. Optimized for comfort and performance.PopularWheel Circumference CalculatorCalculate wheel circumference for bike computer calibration. Supports standard tire presets and custom rim/tire measurements with ETRTO reference table.
Performance6 tools
Estimate watts, calories, FTP zones, climbing speed, and bike weight.
E-Bike Range CalculatorEstimate best, typical, and demanding e-bike range from battery capacity, assist behavior, total load, climbing, speed, wind, temperature, health, and reserve.Cycling Power EstimatorEstimate cycling power output in watts based on speed, gradient, weight, and wind. Calculate W/kg and compare against FTP categories.Calorie CalculatorEstimate calories burned during cycling based on speed, power, duration, and weight. Includes fun food equivalents and activity comparisons.Climbing & VAM CalculatorCalculate gradient percentage and VAM (vertical ascent meters per hour). Compare your climbing performance against benchmarks and famous climbs.Bike Weight EstimatorEstimate your bike weight based on frame material, component choices, and build tier. Detailed component-by-component breakdown for road, MTB, gravel, and e-bikes.FTP CalculatorCalculate your Functional Threshold Power from 20-minute, 8-minute, or ramp test results. Get personalized training zones and W/kg classification.
Why Cyclists Trust BikeSize
Every calculator is free, with no signup required - just accurate results.
Pro-Level Accuracy
Our formulas match the methods professional bike fitters use — inseam multipliers, standover ratios, and reach-stack geometry.
Every Bike Type Covered
Road, mountain, gravel, kids, e-bike, BMX, and triathlon - plus saddle, stem, tire pressure, and crank length tools.
Backed by Real Guides
Each calculator links to a detailed fitting guide so you understand the "why" behind your numbers.
Need More Help?
Check out our comprehensive guides for additional bike fitting and selection advice.