Pulley Ratio Calculator
Calculate the pulley ratio and output speed for belt or chain drive systems. Supports metric (mm, teeth) and imperial (inches, teeth) units. Results are shown as wheel-shaped pulley visualizations in chart view by default.
Pulley Pair 1
Result
Detailed Steps
Pulley Ratio Visualization
Formula
Pulley Ratio Calculation
Pulley ratio is calculated as:
Output speed (if RPM provided):
Notes:
- Size can be diameter (mm or inches) or number of teeth.
- Metric: mm or teeth; Imperial: inches or teeth.
- Typical sizes:
- Belt pulleys: 50–500 mm (2–20 inches)
- Toothed pulleys: 10–100 teeth
- RPM: 100–3000
- A ratio > 1 means the driven pulley rotates slower; < 1 means faster.
How to Use the Pulley Ratio Calculator
- Select the unit system (Metric or Imperial).
- Choose size type (Diameter or Number of Teeth).
- Optionally enter input RPM for speed calculations.
- For each pulley pair, enter driver and driven pulley sizes.
- Add more pulley pairs as needed using the “Add Pulley Pair” button.
- Select display mode (Chart View is default).
- Click “Calculate” to view results, including pulley ratios and a wheel-shaped visualization.
Frequently Asked Questions (FAQs)
What is a pulley ratio?
It’s the ratio of the driven pulley’s size to the driver pulley’s size, determining speed and torque changes in a belt or chain drive system.
How does the ratio affect speed?
A ratio > 1 reduces output speed (increases torque); a ratio < 1 increases output speed (reduces torque).
Can I use teeth instead of diameter?
Yes, for toothed pulleys, enter the number of teeth. The calculation is the same.
What are typical pulley sizes?
Belt pulleys: 50–500 mm (2–20 inches); toothed pulleys: 10–100 teeth. Adjust based on your system.
Why use the chart view?
It visualizes pulley pairs as wheel-shaped pulleys connected by a belt, with ratios labeled, making comparisons intuitive.