Pulley Speed Calculator
Driven pulley speed, drive ratio and belt linear speed from two pulley diameters.
Results
Rotational speed
580.00
rpm
Ratio
2.5000
Speed
7.592
m/s
What this tool does
A belt drive keeps the belt speed the same on both pulleys, so the rotational speeds are inversely proportional to the diameters. Belt linear speed is also given, because most belt types have a maximum working speed that should not be exceeded.
Formula
n₁ × d₁ = n₂ × d₂
Variables
| Symbol | Meaning | Unit |
|---|---|---|
d1 | Diameter | mm |
n1 | Rotational speed | rpm |
d2 | Diameter | mm |
n2 | Rotational speed | rpm |
i | Ratio | — |
v | Speed | m/s |
Worked example
- Diameter100 mm
- Rotational speed1450 rpm
- Diameter250 mm
- Rotational speed580.00 rpm
- Ratio2.5000
- Speed7.592 m/s
Limitations
- The formula assumes ideal conditions: no friction losses, no air resistance and no efficiency losses unless you enter them.