Loading the page...
Preparing tools and content for you. This usually takes a second.
Preparing tools and content for you. This usually takes a second.
Fetching calculator categories and tools for this section.
Use our free RPM calculator to convert linear speed (mph, km/h, m/s, ft/s) into wheel RPM using radius or diameter, or run the inverse: RPM → road speed. Includes angular velocity (rad/s) for physics and shop math.
Last updated: March 21, 2026
A point on the outer edge of a wheel travels faster than a point closer to the center, even though the entire wheel has the exact same RPM. That's why the wheel's radius is so critical for this calculation!
RPM counts how many full turns a wheel, shaft, or cutter makes in one minute. It is not the same as road speed: a small wheel must spin faster (more RPM) than a large wheel to reach the same linear velocity, because each revolution covers a shorter distance (circumference = 2πr).
Linking mph/km/h to RPM is standard in automotive and cycling sizing, conveyor rollers, and machining (drill/lathe surface speed). This page uses the rigid-body relation v = rω, then converts ω in rad/s to RPM.
The form converts everything to meters and m/s, then applies the same physics you would write by hand.
v = r × ω
v: linear speed at the rim (m/s). r: radius in meters (half of diameter if you enter diameter). ω: angular speed in radians per second.
RPM = ω × (60 / 2π)
Converts rad/s to revolutions per minute (one rev = 2π rad; 60 seconds per minute).
ω = RPM × (2π / 60)
Used in Find Velocity mode: given RPM, recover ω, then v = rω, then convert m/s to mph or km/h.
Numbers below use the same math as the calculator (see defaults in the form).
With 26 in diameter (radius ≈ 0.330 m) and 60 mph, ω ≈ 81.23 rad/s → about 775.7 RPM.
Shorter circumference ⇒ more revolutions per mile. At 60 mph, RPM rises to about 1008.4—roughly 30% faster spin than a 26″ tire.
At 1000 RPM, linear speed ≈ 77.3 mph (124.5 km/h) for that diameter—useful for sanity-checking tach-style numbers.
How diameter and speed move RPM: same tool, four related scenarios (values from the same equations as the form).
| Scenario | Diameter | Speed or RPM | Result |
|---|---|---|---|
| Default (bicycle-scale tire) | 26 in | 60 mph | 775.7 RPM |
| Smaller wheel, same road speed | 20 in | 60 mph | 1008.4 RPM |
| Same tire, half speed | 26 in | 30 mph | 387.8 RPM |
| Find speed from rotation | 26 in | 1000 RPM | 77.3 mph |
The form defaults to 26 in diameter, 60 mph in Find RPM mode—about 775.7 RPM and 81.231 rad/s. Switch to Find Velocity and enter 1000 RPM to cross-check highway-scale speeds for the same tire size.
How does a spinning object move you forward? Through contact with the ground or belt. Here's how geometry ties linear speed and RPM together.
Linear speed is the straight-line distance a vehicle travels over time (e.g. 60 mph down the highway). To link this to a wheel, we imagine the wheel "unrolling" its circumference onto the pavement.
Formula: v = r × ω
Angular speed strictly measures how quickly an object is rotating. In physics formulas, this is measured in radians per second (rad/s) because radians inherently link angles to arc lengths (distance). We convert this to RPM for real-world usability.
Formula: ω = RPM × (2π / 60)
Help automotive enthusiasts and engineering students save time when sizing up gears and tires.
Suggested hashtags: #Physics #Engineering #Automotive #Mechanics #MathHelp