⚙️ If you’re working with gears — whether on a bike, a car, or a robot — understanding how they affect speed is important. That’s where a Gear Ratio to RPM Calculator comes in handy!
In this post we provide a handy Calculator and explain the various quantities. As well, we have included examples.
Table of Contents
Use the tool below to calculate
- Output RPM from the Gear Ratio – Enter the input RPM, Driving Gear Teeth and Driven Gear Teeth
- Gear ratio – Enter the Input and Output RPM
⚙️ Gear Ratio & RPM Calculator
🙋♀️ What Is Gear Ratio?
The gear ratio is how many times one gear turns compared to another. It compares the size (or number of teeth) of two connected gears:
Gear Ratio = Teeth on Driven Gear ÷ Teeth on Driving Gear- Driving gear = the gear that’s powered (e.g. motor, pedals)
- Driven gear = the gear that’s turned by the driving gear
🙋 What Is RPM?
RPM stands for Revolutions Per Minute — it’s how fast something is spinning.
In gear systems, if the input (driving) gear turns at a certain RPM, you can calculate how fast the output (driven) gear will spin based on the gear ratio.
🔢 The Formula
Here's the simple formula to calculate output RPM:
Output RPM = Input RPM × (Driving Gear Teeth ÷ Driven Gear Teeth)Or:
Output RPM = Input RPM ÷ Gear RatioBoth mean the same thing!
✅ Example
Let’s say:
- Input RPM = 1000
- Driving gear has 20 teeth
- Driven gear has 40 teeth
Step 1: Gear Ratio
Gear Ratio = 40 ÷ 20 = 2Step 2: Output RPM
Output RPM = 1000 ÷ 2 = 500 RPM🎉 The driven gear spins at 500 RPM — half as fast as the input!
📌 Why This Matters
- Helps with speed and torque planning
- Useful for designing mechanical systems
- Makes troubleshooting gear setups easier
- Perfect for mechanics, engineers, hobbyists, and tinkerers
🧮 Try It Yourself!
Use our handy Gear Ratio to RPM Calculator to plug in your own values and see the results instantly. All you need is:
- Input RPM
- Number of teeth on each gear
⚙️ You change the gear ratio, it changes the speed. Simple as that!