Power Transmission Calculators

Every calculator on the site, grouped by the job. Each one shows the formula and the steps with your numbers, lets you mix metric and US units, keeps its inputs in the link so you can share or repeat a result, and prints a dated record. Nothing you type is uploaded.

Gears

• Gear ratio calculator — ratio, output speed and torque of a gear train, and tooth counts for a target ratio.
• Gearbox calculator — reducer output speed, torque and power with efficiency and service factor.
• Spur gear calculator — pitch, outside, root and base diameters from module or diametral pitch.
• Planetary gear calculator — ratios of a planetary set with any member held, and an assembly check.

Vehicles and bicycles

• Axle ratio calculator — engine rpm, speed, axle ratio and tire size, and the effect of new tires.
• Bicycle gear calculator — gear inches, development and speed for every chainring and cog.
• Tire size calculator — diameter, sidewall, revolutions per mile and metric to inch sizes.
• Tire size comparison — compare up to three tire sizes and the speedometer error.
• Offset rim calculator — wheel offset to backspacing, and how a new wheel moves in and out.
• Tire speed rating chart — speed symbols A1 to Y in mph and km/h, a tire code decoder and the lowest symbol for a top speed.
• Tire load index chart — load index 0 to 279 in kg and lb, and the lowest index for a load.
• Wheel bolt pattern chart — bolt circle from a stud measurement, mm to inch patterns and lug nut thread size.

Chains and sprockets

• Sprocket calculator — sprocket ratio, pitch and outside diameter, chain speed and final-drive changes.
• Chain length calculator — roller chain links for two sprockets, and bicycle chain length.
• Roller chain size chart — ANSI and ISO chain pitch, roller and width, and chain identification.

Belts and conveyors

• Belt length calculator — belt length or centre distance for two pulleys, wrap angle and speed ratio.
• V-belt calculator — pitch length and the nearest standard V-belt size.
• Timing belt calculator — synchronous belt length and tooth count, and exact centre distance.
• Conveyor speed calculator — belt speed from pulley size and rpm, and throughput.

Shafts, bearings and torque

• Torque calculator and converter — N·m, ft·lb and in·lb conversion, torque from force or power, wrench extensions.
• Bearing life calculator — L10 rating life in revolutions and hours, and the load rating needed.
• Bearing size chart — bore, outside diameter and width of ball bearings by number.
• Keyway calculator — keyseat and keyway depths and the chordal height for a shaft and key.

All results are estimates for design checks; verify critical designs against the applicable standard and the manufacturer’s data. You may use the results in commercial work.