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Propeller Thrust Calculator

Calculate propeller static thrust from diameter, pitch, RPM, and air density. Estimate drone and RC aircraft motor-prop combinations.

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Inputs that matter
Propeller Diameter, RPM, Number of Blades
Output to expect
Propeller Thrust Calculator
  • Check the units and required inputs before comparing results.
  • Keep the assumptions with a copied result so you can reproduce the calculation later.
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Reference & details

How it works

Momentum Theory Baseline

Ideal static thrust from actuator disk theory relates power and air velocity. Real props achieve 50–70% of ideal due to losses.

T_ideal = 2 × ρ × A × v² (actuator disk approximation)

Empirical Prop Thrust Formula

A common RC approximation scales thrust with diameter^3, RPM², and inverse pitch factor. Blade count adds marginal thrust at same diameter.

T (oz) ≈ k × D³ × (RPM/1000)² / pitch_factor

Air Density Correction

Thrust decreases at altitude and high temperature. Sea-level density 1.225 kg/m³ is standard; reduce ~3% per 1000 ft altitude.

T_alt = T_sea level × (ρ_alt / ρ_sea level)

Updated: July 2026

Example Scenarios

5-inch (127 mm) prop, 4.3 pitch, 3-blade at 25k RPM: estimated ~800–950 g static thrust per motor. Quad total ~3.2–3.8 kg — suitable for 2–2.5 kg AUW with 1.5:1 thrust ratio.

10-inch 2-blade at 10,000 RPM on 3S: ~35–40 oz thrust. For 2.5 lb (40 oz) plane, 1:1 static thrust is adequate; aerodynamic lift provides margin in flight.

At 5000 ft, air density ~86% of sea level. Recalculate thrust — same setup produces ~14% less static thrust; size up prop or increase RPM.

Common Mistakes to Avoid

Sizing motors from prop diameter alone without RPM

Thrust scales with RPM squared. The same 5-inch prop at 15k vs 30k RPM produces vastly different thrust — always include KV, voltage, and loaded RPM.

Ignoring altitude when flying in mountains

Reduced air density at elevation cuts thrust significantly. Rebalance prop size or battery voltage for high-altitude flying locations.

FAQ

Minimum 2:1 for stable hover and maneuverability. Freestyle and racing aim for 4:1–8:1. Heavier cinematic rigs accept 2.5:1 with larger props.

Lower pitch generates more static thrust at the same RPM but lower top speed. Higher pitch trades static thrust for higher pitch speed — better for fast forward flight.

At the same diameter and RPM, 3-blade props produce roughly 5–10% more thrust than 2-blade but draw more current and reduce efficiency slightly.

No. Forward flight reduces effective angle of attack on the prop, changing thrust. Static thrust is a bench measurement — useful for sizing but not identical to cruise thrust.

Use a thrust stand with load cell, or scale-method: mount motor on scale, record negative weight at full throttle. Compare measured to calculated for your specific prop-motor combo.

About Propeller Thrust Calculator

Matching propeller thrust to aircraft weight is fundamental for RC drones and planes. This calculator estimates static thrust from prop diameter, pitch, RPM, blade count, and air density using momentum and empirical prop models.