Mechanical Engineering
Torque Calculator
Torque from force and lever arm (τ = F·r), solving for any variable, in N·m and lb·ft.
τ = F × r × sin θ (θ = 90° for maximum to…
Also called torque formula · moment of force
Engineering · 10 calculators
Mechanical Engineering Calculators
Torque, horsepower, RPM, gear and pulley ratios, belt length, power-to-weight, efficiency and spring rate.
Mechanical Engineering
Horsepower Calculator
Horsepower from torque and RPM, from watts, or from the quarter-mile trap speed.
P (W) = τ × 2π × RPM / 60
Also called hp calculator · torque to hp
Mechanical Engineering
RPM Calculator
Convert between RPM, surface speed and angular velocity for shafts, wheels and tools.
surface speed = π × d × RPM
Also called revolutions per minute · rpm to rad/s
Mechanical Engineering
Gear Ratio Calculator
Gear ratio from tooth counts or diameters, with output speed, torque and direction.
ratio = driven teeth ÷ driving teeth
Also called gearing calculator · gear teeth ratio
Mechanical Engineering
Mechanical Advantage Calculator
Mechanical advantage of levers, pulleys, ramps and gears — ideal and actual, with efficiency.
MA = load ÷ effort = effort arm ÷ load arm
Also called ma calculator · lever advantage
Mechanical Engineering
Pulley Ratio Calculator
Pulley or sheave ratio from diameters, with driven speed, torque and belt speed.
ratio = driven diameter ÷ driver diameter
Also called sheave ratio · belt drive ratio
Mechanical Engineering
Belt Length Calculator
Required belt length for a two-pulley drive from the diameters and centre distance.
L ≈ 2C + π(D₁ + D₂)/2 + (D₂ − D₁)² / 4C
Also called v belt length · pulley belt length
Mechanical Engineering
Power to Weight Ratio Calculator
Power-to-weight ratio in hp/tonne and W/kg, with an estimated 0–100 km/h time.
ratio = power ÷ total weight
Also called hp per ton · w/kg calculator
Mechanical Engineering
Efficiency Calculator
Efficiency as output ÷ input × 100 — for machines, energy conversion, processes or work.
Efficiency = Useful output ÷ Total input …
Also called efficiency formula · machine efficiency
Mechanical Engineering
Spring Rate Calculator
Spring rate from wire and coil dimensions, or from load and deflection, with the force at any travel.
k = G·d⁴ / (8·D³·n)
Also called spring constant calculator · coil spring rate
Key mechanical engineering formulas
| Torque | τ = F × r × sin θ (θ = 90° for maximum torque) |
|---|---|
| Horsepower | P (W) = τ × 2π × RPM / 60 · 1 hp = 745.7 W |
| RPM | surface speed = π × d × RPM · ω = 2π × RPM / 60 |
| Gear Ratio | ratio = driven teeth ÷ driving teeth |
| Mechanical Advantage | MA = load ÷ effort = effort arm ÷ load arm |
| Pulley Ratio | ratio = driven diameter ÷ driver diameter |
| Belt Length | L ≈ 2C + π(D₁ + D₂)/2 + (D₂ − D₁)² / 4C |
| Power to Weight Ratio | ratio = power ÷ total weight |
| Efficiency | Efficiency = Useful output ÷ Total input × 100 |
| Spring Rate | k = G·d⁴ / (8·D³·n) · F = k·x |
Mechanical Engineering questions
What is the difference between hp and PS?
Metric horsepower (PS or CV) is 735.5 W, about 1.4% smaller than the 745.7 W mechanical horsepower.
Does a higher gear ratio mean more speed?
No — a higher numeric ratio means more torque and lower output speed. Overdrive ratios are below 1.