Gear Module Calculator

Inputs

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Choose whether the entered diameter is the pitch circle diameter or the outside tip diameter. Tip diameter uses m ≈ OD / (z + 2) for a standard full-depth spur gear.
Measured gear diameter. Use pitch diameter when known; for an existing standard full-depth gear, tip/outside diameter is often easier to measure.
mm
Number of teeth on the gear.

Results

Default result
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Measured module(m)
2mm

Module is calculated directly from pitch diameter: m = d / z. Equivalent DP 12.7 (1/in).

Also computed

Nearest ISO module(m_std)Pass2mm

Nearest ISO 54 listed module; series 1.

Delta to ISO module(Δm)Pass0%

Measured module is close to the nearest listed ISO module.

ISO module series1series

Series 1 is the first-choice ISO module series.

Diametral pitch(DP)12.7

1/in

Circular pitch(p)6.283mm

Pitch diameter used(d)40mm

Method notes 4 notes
  • Module m = pitch diameter ÷ tooth count. From a standard full-depth outside diameter, m ≈ tip diameter ÷ (z + 2).
  • Diametral pitch DP = 25.4 / m, so module and DP are reciprocals scaled by 25.4.
  • Nearest ISO module is a measurement check, not proof of gear standard, pressure angle, profile shift, backlash or tooth quality.
  • Mating gears must share the same module and pressure angle.

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