Prop Slip Calculator
Find propeller slip from theoretical and actual speed.
Prop slip is the difference between a propeller's theoretical and actual travel.
The math behind it
slip = (theoretical − actual) ÷ theoretical × 100. Some slip is normal and necessary to generate thrust.
Worked example
79 mph theoretical vs 65 actual → about 17.7% slip.
FAQ
What's a good slip figure?
Around 10–15% for efficient props; very high slip suggests the wrong prop.