Calculate propeller pitch speed, tip speed, tip Mach number, advance ratio, and pitch angle for RC, drone, aircraft, and boat propellers.
Propeller pitch is the theoretical distance a propeller would advance in one revolution if there were no slip — like a screw threading into wood. A 12×6 propeller has 12 inches diameter and 6 inches pitch, meaning it theoretically advances 6 inches per revolution.
This calculator computes the theoretical pitch speed (MPH, knots, m/s), tip speed and Mach number, pitch angle at 75% radius, and advance ratio. Tip Mach number is critical — when the blade tips approach Mach 0.85-0.9, compressibility effects cause dramatic efficiency loss and noise.
Preset buttons cover RC model aircraft (2-blade 12×6), multirotors (10×4.5), full-scale Cessna (75×56), and boat propellers. The calculator handles both inch and millimeter inputs. A pitch selection guide helps choose the right pitch for hovering vs speed applications.
Whether you are selecting a propeller for a drone, tuning an RC racing plane, or analyzing a Cessna 172's constant-speed prop, this tool provides the key performance parameters.
Propeller pitch needs to be checked against both the speed you want and the speed the blade tips are already carrying. Pitch speed, tip Mach, and advance ratio together show whether a prop is likely to be efficient, noisy, or simply mismatched.
Pitch speed = Pitch × RPM (distance per minute). Tip speed = π × D × RPM / 60. Pitch angle at r: θ = atan(P / (2πr)). Advance ratio: J = V / (n × D). P/D ratio = Pitch / Diameter.
Result: Pitch speed = 54.5 mph, tip speed = 128 m/s, Mach = 0.37
Pitch speed = 6/12 ft × 8000 = 4000 ft/min = 45.5 mph. Tip: π × 1ft × 8000/60 = 418 ft/s = 128 m/s. Mach = 128/343 = 0.37 (safe).
Pitch speed is the idealized forward speed implied by the geometry of the propeller. Real vehicles move slower than that because the prop always has some slip. Looking at pitch speed together with actual operating speed helps show how much of the blade geometry is being turned into useful advance.
As blade tips move closer to transonic speed, compressibility effects begin to hurt efficiency and increase noise. That is why a prop can look fine by pitch ratio alone but still be a poor choice once RPM and diameter are included.
The best prop is not just the one with the biggest pitch or diameter. Matching propeller geometry to the operating point is what usually matters most for drones, RC aircraft, boats, and light aircraft.
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Pitch is the theoretical advance per revolution. Actual advance is less due to slip — typically 10-30% for aircraft props and 20-40% for boat props. Efficiency = actual advance / pitch.
Low pitch (like low gear): more thrust, less speed — good for hovering, climbing, heavy loads. High pitch (like high gear): less thrust, more speed — good for cruise, racing.
When blade tips approach the speed of sound (Mach 0.85+), shock waves form, dramatically increasing drag and noise while reducing thrust. Keep tip Mach below 0.85.
J = V/(nD) where V is airspeed, n is rev/sec, D is diameter. It determines the operating point on the propeller efficiency curve. Peak efficiency is typically at J = 0.5-0.9.
Larger diameter increases disk area and theoretical efficiency (momentum theory), but also increases tip speed, weight, and ground clearance requirements. The optimum balances these factors.
P/D ratio compares pitch to diameter. Low P/D (0.3-0.5) = high thrust, low speed (tugboats, copters). High P/D (0.8-1.2) = low thrust, high speed (fast boats, cruise aircraft).