What does propeller pitch mean?

Pitch is the theoretical distance the propeller would advance in one revolution if there were no slippage, like a screw moving through a solid. A 6-inch pitch prop moves forward 6 inches per revolution in theory. Higher pitch = more speed but more load on the motor.

Why is theoretical speed different from actual speed?

Theoretical speed assumes zero slippage. In reality, propellers are typically 60-80% efficient due to air resistance, blade design, tip losses and operating conditions. A 75% efficiency factor is a reasonable estimate for most RC applications.

What is tip speed and why does it matter?

Tip speed is how fast the outer edge of the propeller moves through the air. When tip speed approaches the speed of sound (Mach 1, ~343 m/s), efficiency drops dramatically and noise increases. Keep tip speed below Mach 0.7 for best results.

How do I choose between pitch and diameter?

Larger diameter provides more thrust at lower speeds (better for takeoff and climbing). Higher pitch provides more speed but requires more power. For slow flyers and trainers, use larger diameter with lower pitch. For speed models, use smaller diameter with higher pitch.

ModelCalcs

Propeller Pitch Speed Calculator \u2014 Theoretical Max Speed

Calculate theoretical max speed from propeller diameter, pitch and RPM.

Propeller Diameter

Total diameter of the prop

Propeller Pitch

Distance per revolution (theoretical)

Motor RPM

Revolutions per minute at full throttle

Units

Prop sizing measurement system

How We Calculate This

This calculator determines theoretical maximum airspeed from propeller pitch and RPM, then adjusts for real-world efficiency losses.

How it works

Theoretical speed = pitch x RPM, converted to mph/kph. The adjusted speed applies an efficiency factor (default 75%) to account for propeller slippage. Tip speed is calculated from diameter and RPM to check for transonic effects.

Frequently Asked Questions

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Last updated: March 2026

All calculations are estimates. Always verify quantities before purchasing materials.