Gear Ratio Calculator

MECHANICAL

GR = Nᵢₙ / Nₒᵤₜ · Speed · Torque · Compound gears · Mechanical advantage

GR RPM Torque

Enter teeth count or RPM — solve for gear ratio and output speed

Drive gear teeth (N₁)

teeth

Driven gear teeth (N₂)

teeth

Input RPM (optional)

RPM

                            Gear ratio (GR)
                            —
                            :1
                        

Speed reduction — ×

Mechanical advantage — ×

GR = N₂ / N₁ | RPMₒᵤₜ = RPMᵢₙ / GR

Drive gear → Driven gear (external mesh)

Enter teeth for up to 4 gears in a compound train

N₁ (input)

N₂

N₃

N₄ (output)

Input RPM

RPM

                            Total gear ratio
                            —
                            :1
                        

Stage 1 ratio — :1

Stage 2 ratio — :1

Total reduction — ×

GR_total = (N₂/N₁) × (N₄/N₃)

N₂ and N₃ are compound (same shaft)

Calculate output torque and speed from gear ratio

Gear ratio (GR)

Input speed

RPM

Input torque

N·m

                            Output torque
                            —
                            N·m
                        

                            Output speed
                            —
                            RPM
                        

Torque multiplier — ×

Speed multiplier — ×

Power (input = output) — kW

Tₒᵤₜ = Tᵢₙ × GR | RPMₒᵤₜ = RPMᵢₙ / GR

Torque increases with gear ratio (constant input)

Power in = Power out (ideal gears)