TWR Calculator

Eliot GeversEliot Gevers

Calculate the Thrust-to-Weight Ratio (TWR) for aircraft or rockets. TWR determines whether a vehicle can achieve vertical flight and provides insight into acceleration capabilities.

Thrust-to-Weight Ratio

TWR = T / W = T / (m × g)
Where T is thrust, W is weight, m is mass, and g is gravity

Where:

  • TWRThrust-to-Weight Ratio (dimensionless)
  • TThrust force produced by the engine
  • WWeight of the vehicle (mass × gravity)
  • mMass of the vehicle
  • gGravitational acceleration (9.80665 m/s² on Earth)

TWR Guidelines:

  • TWR > 1: Vehicle can hover and accelerate vertically (rockets, helicopters)
  • TWR = 1: Vehicle can hover but cannot accelerate vertically
  • TWR < 1: Vehicle requires horizontal motion for lift (airplanes)
  • Rockets typically need TWR > 1.2 at liftoff to overcome gravity and drag
  • Aircraft typically have TWR < 0.5, relying on aerodynamic lift
  • Higher TWR provides better acceleration but requires more fuel

Typical TWR Values:

  • Commercial Aircraft: 0.2 - 0.4
  • Military Aircraft: 0.5 - 1.0
  • Helicopters: 1.1 - 1.5
  • Rockets (Liftoff): 1.2 - 2.0
  • Space Shuttle: ~1.5
  • Saturn V: ~1.2

Open Source & Transparent

This tool is open source and the underlying logic is fully transparent. You can view the source code, understand the calculations, and even contribute improvements to make it better for everyone.

View Source Code