What is module in gears?

Module m = pitch diameter / number of teeth (mm). Standard values: 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 10.

How to select number of teeth?

Minimum 18–20 for spur to avoid undercut. Higher teeth → smoother but larger size.

Steel: bending 100–300 MPa, wear 500–1200 MPa. Cast iron lower.

Design spur, helical, worm and bevel gears from power, speed and ratio. Calculate module, teeth, center distance and strength instantly.

Recommended Module

m = 3 mm

For 10 kW, 1440 RPM, ratio 3:1, steel

Featured: Spur, Helical, Worm, Bevel • Lewis Beam Strength

Power P (kW)

Pinion Speed n₁ (RPM)

Gear Ratio i (N₂/N₁)

Gear Type

Helix Angle β (°) - for Helical

Material (Bending Stress σb MPa)

Factor of Safety

Face Width b (mm) ≈ 10m

Lewis Beam Strength Method

Classic bending strength check (most common for preliminary design).

Wt = σb × b × m × y × π / FS
m ≥ ∛(Wt × FS / (σb × b × π × y))

Enter parameters and click Calculate

Simple, efficient, noisy at high speed.

Smoother, axial thrust load.

90° power transmission.

High ratio, self-locking possible.