👤 By whycalculator Team 📅 Last Updated February 23, 2026
RPM to Feet Per Second
| RPM | Diameter (ft) | Feet / Second (ft/s) |
|---|---|---|
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This RPM to Feet per Second (ft/s) calculator helps you understand how fast the outer edge of a rotating object is actually moving in real time. Instead of just seeing revolutions per minute, you can convert that rotational speed into true linear velocity. It’s especially useful in machining, mechanical systems, conveyors, and cutting applications where surface speed matters. If you need results in minutes instead of seconds, you can also check our RPM to FPM calculator for quick conversion to feet per minute.
How to Convert RPM to Feet Per Second (ft/s)
To convert RPM (Revolutions Per Minute) into Feet Per Second (ft/s), we calculate how far the outer edge of a rotating object travels in one second. This depends on the circumference of the object and the rotational speed.
Step 1: Calculate the Circumference
The circumference of a circle is:
Circumference = π × Diameter
If the diameter is not in feet, convert it to feet first:
- Inches → divide by 12
- Centimeters → divide by 30.48
- Meters → multiply by 3.28084
Step 2: Multiply by RPM
This gives distance traveled per minute:
Feet per Minute (FPM) = π × Diameter (ft) × RPM
Step 3: Convert Minutes to Seconds
Since 1 minute = 60 seconds:
Feet per Second (ft/s) = (π × Diameter (ft) × RPM) ÷ 60
Direct Formula (Diameter in Inches)
If diameter is in inches, use:
ft/s = (3.1416 × Diameter × RPM) ÷ (12 × 60)
This simplifies to:
ft/s ≈ 0.00436 × Diameter × RPM
Example 1
RPM = 1000
Diameter = 6 inches
Step 1: Convert inches to feet → 6 ÷ 12 = 0.5 ft
Step 2:
ft/s = (3.1416 × 0.5 × 1000) ÷ 60
ft/s = 26.18 ft/s
Example 2
RPM = 750
Diameter = 8 inches
Convert diameter → 8 ÷ 12 = 0.667 ft
ft/s = (3.1416 × 0.667 × 750) ÷ 60
ft/s ≈ 26.18 ft/s
Even though RPM and diameter are different, the resulting surface speed can sometimes be similar.
RPM to Feet per Second (ft/s) Reference Table
| RPM | Diameter (Inch) | Feet per Second (ft/s) |
|---|---|---|
| 500 | 4 | 8.73 |
| 750 | 6 | 19.63 |
| 1000 | 6 | 26.18 |
| 1200 | 8 | 41.89 |
| 1500 | 10 | 65.45 |
Values calculated using: ft/s = (3.1416 × Diameter × RPM) ÷ (12 × 60)
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