Pulley Calculator

Inputs

View results
Pitch diameter of the driving pulley (on the motor / input shaft).
mm
Pitch diameter of the driven pulley (on the output shaft).
mm
Speed of the driving pulley / motor.
rpm

Results

Default result
Edit inputs
Pulley ratio(i)
2.5
Pass

reduction

driven ÷ driver (n:1).

Also computed

Driven speed(n₂)700rpm

Belt speed(v)9.163m/s

Surface (rim) speed of the belt.

Method notes 4 notes
  • Ratio i = driven diameter ÷ driver diameter. Driven speed n₂ = n₁ · D₁ / D₂.
  • This drive is a reduction (driven slower than driver).
  • Belt (surface) speed v = π · D · n uses the driver pulley — the belt runs at the same surface speed on both pulleys (no slip).
  • Diameters are pitch (effective) diameters, not the outer rim; for V-belts use the pitch diameter, not the OD.

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