Speed from RPM Calculator
Fill in the values and the answer updates as you type.
How the Speed from RPM Calculator works
Speed (mph) = RPM × tire diameter (in) × π × 60 ÷ (overall ratio × 63,360). Overall ratio = transmission gear ratio × final drive ratio. Example: with Engine speed 2,500 rpm, Tire diameter 26 in, and Overall gear ratio 9.5, the result is Speed (mph) = 20.4; Speed (km/h) = 32.8.
Inputs and results
The Speed from RPM Calculator takes 3 inputs and gives 2 results.
What you enter
- Engine speed (rpm) — starts at 2500.
- Tire diameter (in) — starts at 26.
- Overall gear ratio — starts at 9.5.
What you get
- Speed (mph)
- Speed (km/h)
Example: Speed from RPM Calculator with the starting values
With engine speed 2500 rpm, tire diameter 26 in and overall gear ratio 9.5, the calculator returns:
| Speed (mph) | 20.4 |
|---|---|
| Speed (km/h) | 32.8 |
Change any value above and the results update straight away.
Speed from RPM Calculator FAQ
How do I use the Speed from RPM Calculator?
Enter engine speed, tire diameter and overall gear ratio in the fields, then read speed (mph) and speed (km/h) in the result panel. The answer updates as you type, and you can press Calculate or Enter to refresh it. Use “Copy link” to share your exact numbers with someone else.
What does the Speed from RPM Calculator calculate?
Vehicle speed from engine RPM, tire size, and gear ratio. It returns speed (mph) and speed (km/h) from the 3 values you provide.
What values does the Speed from RPM Calculator start with?
It opens with engine speed 2500 rpm, tire diameter 26 in and overall gear ratio 9.5 so you can see a working result straight away. Replace them with your own numbers, or press Reset to return to these starting values.
Is the Speed from RPM Calculator free and private?
Yes. It is free, needs no account, and runs in your browser, so nothing you type is sent to or stored on our servers. See the Privacy Policy for details.
Can I rely on the Speed from RPM Calculator for important decisions?
Treat the result as a well-rounded estimate. Real situations often have details a general calculator cannot know, so confirm important decisions with a qualified professional. See the Disclaimer for more.