Our gear ratio speed calculator covers every powertrain configuration — from the single speed gear ratio speed calculator for fixie bikes to the semi truck gear ratio speed calculator for 18-wheelers. Click any card to load defaults.
Our bicycle gear ratio speed calculator, cycling gear ratio speed calculator, mtb gear ratio speed calculator, apex garage gear ratio speed calculator equivalent, and single speed gear ratio speed calculator use chainring/sprocket teeth ratio and wheel circumference. Shows all cassette gears simultaneously.
Our motorcycle gear ratio speed calculator and gear ratio speed calculator motorcycle covers the complete drivetrain: engine RPM + transmission gear ratio + primary drive ratio + sprocket ratio + wheel size.
Our dirt bike gear ratio speed calculator and atv gear ratio speed calculator — smaller wheels and higher RPM engines. Essential for re-gearing calculations when changing sprocket sizes for more speed or better low-end traction.
Our semi truck gear ratio speed calculator handles 10–18 speed transmissions with large axle ratios (3.36–4.30:1) and tall tires (24.5–22.5 inch). Critical for spec'ing the right final drive ratio for fuel economy vs grade climbing.
Our free gear ratio speed calculator is more complete than OmniCalculator, Tremec, and Cajasgraf tools — because it covers 7 vehicle types (car, bicycle, MTB, motorcycle, dirt bike, ATV, semi truck), 3 solve modes (find speed, find RPM, find ratio), shows all gears simultaneously with visual bar charts, includes dedicated presets for bicycle cassettes and car tire sizes, and calculates cycling metrics like gear inches and meters of development. Whether you need a rpm speed and gear ratio calculator, a bike gear ratio speed calculator, a transmission gear ratio speed calculator, or the rpm gear ratio speed calculator formula explained, this is the only tool you need.
Our bicycle gear speed calculator, cycling gear ratio speed calculator, bike gear ratio speed calculator, and single speed gear ratio speed calculator use two additional metrics beyond speed: Gear Inches = Wheel Diameter (inches) × Chainring ÷ Sprocket. This was the original Victorian-era measure of effective wheel size. Development = Wheel Circumference × Chainring ÷ Sprocket. This is the distance traveled per pedal revolution in meters. Example: 50T chainring, 17T sprocket, 700c + 25mm tire (672mm diameter): Gear inches = 26.5 × 50/17 = 77.9 inches. Development = 2.111m × 50/17 = 6.21 meters per pedal revolution = at 90 RPM cadence → 33.4 km/h.
Road bike, 50T chainring, 17T sprocket, 700c + 25mm tire:
Wheel diameter = 622 + (2 × 25) = 672mm = 26.46 inches
Gear ratio = 50 ÷ 17 = 2.94 (step-up → faster than 1:1)
Wheel circumference = 672 × π = 2,111mm = 2.111m
At 90 RPM cadence: Speed = (90 × 2,111mm × 60) ÷ (2.94 × 1,000,000) = 38.8 km/h (24.1 mph)
Gear inches = 26.46 × 2.94 = 77.8 inches
Development = 2.111m × 2.94 = 6.21 m/pedal stroke
The motorcycle gear ratio speed calculator and gear ratio speed calculator motorcycle require 3 ratio inputs: transmission gear ratio (e.g., 6th gear = 0.83:1), primary drive ratio (engine to gearbox, typically 1.5–2.0:1 for chain/gear primary), and final drive sprocket ratio (rear ÷ front sprocket, typically 2.5–4.0:1). Total overall ratio = Trans × Primary × Sprocket. Formula: Speed (km/h) = (Engine RPM × Tire Circumference m) ÷ (Total Ratio × 1000 ÷ 60 × 60). Example: 8,000 RPM, 6th 0.83:1, primary 1.5:1, 15T/46T (3.07:1), 1.98m tire: Total ratio = 0.83 × 1.5 × 3.07 = 3.82. Speed = (8,000 ÷ 3.82) ÷ 60 × 1.98 × 3.6 = approximately 199 km/h.
| Vehicle | Gear Ratio Formula | Speed Formula (km/h) | Typical Ratios |
|---|---|---|---|
| Bicycle | Chainring ÷ Sprocket | (Cadence × Circ mm × 60) ÷ (Ratio × 1,000,000) | 1.5:1 – 5.0:1 |
| Motorcycle | Trans × Primary × Sprocket | (RPM × Circ m × 60) ÷ (Total Ratio × 1,000) | 3:1 – 15:1 total |
| Car/Truck | Trans Gear × Axle Ratio | (RPM × Dia in × π) ÷ (Ratio × 336) × 1.60934 | 1.5:1 – 12:1 total |
| Dirt Bike | Trans × Primary × Sprocket | Same as motorcycle formula | 5:1 – 20:1 total |
| Semi Truck | Trans × Axle (tandem) | Same as car formula | 8:1 – 30:1 total |
RPM gear ratio speed calculator formula tip: To find the ideal sprocket for your dirt bike or ATV, use the Ratio solve mode. Enter your desired top speed and typical engine RPM in your power band (where the engine makes peak power). The calculator gives you the required total gear ratio. Divide by your current primary drive and transmission ratio to find the sprocket ratio needed. Then: Front sprocket teeth = Rear sprocket teeth ÷ Required sprocket ratio. This is the most practical use of our rpm gear ratio speed calculator and gear ratio speed calculator formula rpm for off-road regearing.
Questions covering gear ratio formulas, bicycle speed calculation, motorcycle gearing, dirt bike regearing, and RPM-to-speed conversion.
Our gear ratio speed calculator formula and rpm gear ratio speed calculator formula: Speed (km/h) = (RPM × Wheel Circumference mm × 60) ÷ (Gear Ratio × 1,000,000). For cars specifically — Speed (mph) = (RPM × Tire Diameter inches × π) ÷ (Gear Ratio × Axle Ratio × 336). To find RPM from speed: RPM = (Speed × Gear Ratio × 1,000,000) ÷ (Wheel Circumference mm × 60). To find Ratio from speed + RPM: Ratio = (RPM × Wheel Circumference mm × 60) ÷ (Speed × 1,000,000). All three are built into our rpm speed and gear ratio calculator — select the Solve For mode to switch.
Our bicycle gear ratio speed calculator and cycling gear ratio speed calculator formula: Speed (km/h) = (Cadence RPM × Chainring ÷ Sprocket × Wheel Circumference mm × 60) ÷ 1,000,000. Example: 90 RPM cadence, 50T chainring, 17T sprocket, 700c + 25mm tire = 672mm diameter = 2,111mm circumference: Speed = (90 × 2.941 × 2,111 × 60) ÷ 1,000,000 = 33,542,868 ÷ 1,000,000 = 33.5 km/h. Also shows gear inches = wheel diameter (in) × chainring ÷ sprocket = 26.46 × 2.94 = 77.8 inches. Our bike gear ratio speed calculator, mtb gear ratio speed calculator, apex garage gear ratio speed calculator equivalent, and single speed gear ratio speed calculator all use this formula.
Our motorcycle gear ratio speed calculator and gear ratio speed calculator motorcycle uses: Speed (km/h) = (Engine RPM × Wheel Circumference m × 3600) ÷ (Primary × Trans Gear × Front/Rear Sprocket × 1000). For a sport bike at 8,000 RPM in 6th gear (0.83:1), 1.96:1 primary, 15T/46T sprocket (3.07:1), 1.96m tire: Total ratio = 0.83 × 1.96 × 3.07 = 4.99. Speed = (8,000 ÷ 4.99) ÷ 60 × 1.96 × 60 = approximately 199 km/h. To use our calculator: enter primary ratio in the Axle/Primary field, trans gear in the Drive/Driven ratio, sprocket ratio in the secondary ratio field, or use the total combined ratio directly.
A gear ratio speed calculator reveals this key relationship: Speed is inversely proportional to gear ratio. Double the ratio = half the speed at the same RPM. Triple the ratio = one-third the speed. A 1:1 ratio means the output shaft rotates exactly once per input rotation. Below 1:1 (like 0.70:1 overdrive) is a step-UP ratio — output rotates faster than input — giving higher speed. Above 1:1 (like 3.5:1 first gear) is a step-DOWN ratio — output rotates slower than input — giving more torque but lower speed. For bicycle: 50T ÷ 11T = 4.55:1 means the wheel rotates 4.55 times per pedal revolution. Use our gear and speed calculator to visualize this for any combination.
For regearing a dirt bike gear ratio speed calculator or atv gear ratio speed calculator: 1) Use "Solve For → Ratio" mode. 2) Enter your desired top speed and peak power RPM. 3) The calculator gives the required total gear ratio. 4) Divide by your primary drive and 5th/6th gear ratio to get the sprocket ratio needed. 5) Choose a front/rear sprocket combination that achieves this ratio. Example: need 3.5:1 sprocket ratio → 15T front and 52T rear (52/15 = 3.47:1) works. For a semi truck or car, the same approach works for the transmission gear ratio speed calculator: find the axle ratio that gives your target RPM at highway cruise speed.