Gear Ratio Calculator
Ratio, output speed and torque.
Enter your values
Enter the driving 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 Nm.
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
- 583 rpm
- Output torque
- 36 Nm
- Mechanical advantage
- 3
Quick answer
Gear ratio is driven teeth divided by driving teeth; it trades speed for torque.
Ratio = driven teeth ÷ driving teeth
At a glance
| What it does | Ratio, output speed and torque. |
|---|---|
| Category | Engineering |
| Inputs needed | Driving gear teeth, Driven gear teeth, Input speed, Input torque |
| Main output | Gear ratio |
| Formula | Ratio = driven teeth ÷ driving teeth |
| Cost | Free — no sign-up, no download |
How to use the Gear Ratio Calculator
- 1Enter the tooth count of both gears.
- 2Enter input speed and torque.
- 3Read the output speed and torque.
Inputs explained
- Driving gear teeth
- Enter the driving 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(Nm)
- Enter the input torque in Nm.
Worked example
Using the values the calculator loads with:
Inputs
- Driving gear teeth18
- Driven gear teeth54
- Input speed1750 rpm
- Input torque12 Nm
Results
- Gear ratio3:1
- Output speed583 rpm
- Output torque36 Nm
- Mechanical advantage3
Frequently asked questions
Does a gearbox create power?
No — torque rises only as speed falls, minus friction losses.
What is overdrive?
A ratio below 1:1, which raises speed and reduces torque.
What do I need to enter into the Gear Ratio Calculator?
Just 4 values: driving 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 is driven teeth divided by driving teeth; it trades speed for torque. It applies the formula Ratio = driven teeth ÷ driving teeth 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.