Gear Ratio Calculator
Output speed and torque from gear tooth counts.
Enter your values
Enter the driver gear teeth you are working with.
Enter the driven gear teeth you are working with.
Enter the input speed in RPM.
Enter the input torque in N·m.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Gear ratio
- 3:1
- Output speed
- 600 RPM
- Output torque
- 30 N·m
Quick answer
Gear ratio = driven teeth / driver teeth; output speed = input speed / ratio.
ratio = T_driven / T_driver
At a glance
| What it does | Output speed and torque from gear tooth counts. |
|---|---|
| Category | Engineering |
| Inputs needed | Driver gear teeth, Driven gear teeth, Input speed, Input torque |
| Main output | Gear ratio |
| Formula | ratio = T_driven / T_driver |
| Cost | Free — no sign-up, no download |
How to use the Gear Ratio Calculator
- 1Enter the number of teeth on the driver and driven gears.
- 2Enter the input speed and torque.
- 3Read the gear ratio, output speed and output torque.
Inputs explained
- Driver gear teeth
- Enter the driver gear teeth you are working with.
- Driven gear teeth
- Enter the driven gear teeth you are working with.
- Input speed(RPM)
- Enter the input speed in RPM.
- Input torque(N·m)
- Enter the input torque in N·m.
Worked example
Using the values the calculator loads with:
Inputs
- Driver gear teeth20
- Driven gear teeth60
- Input speed1800 RPM
- Input torque10 N·m
Results
- Gear ratio3:1
- Output speed600 RPM
- Output torque30 N·m
Frequently asked questions
Does gear ratio change power?
No, ideal gears trade speed for torque but keep power roughly constant, minus small friction losses.
What is a reduction gear?
When the driven gear has more teeth than the driver, output speed drops and torque increases.
What do I need to enter into the Gear Ratio Calculator?
Just 4 values: driver gear teeth, driven gear teeth, input speed, input torque. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Gear Ratio Calculator work out the answer?
Gear ratio = driven teeth / driver teeth; output speed = input speed / ratio. It applies the formula ratio = T_driven / T_driver and shows the working so you can check each step by hand.
Is the Gear Ratio Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.