Thrust-to-Weight Ratio Calculator
The thrust-to-weight ratio compares an engine’s push with the vehicle’s weight. A rocket needs a ratio above 1 to lift off; the extra decides how fast it accelerates at first.
Standards:
- NGSS HS-PS2-1
- AP1 Unit 2
- IB A.2
Our alignment; not reviewed by the standards bodies.
The equation
Worked example
- Given
- Thrust F (kN): 6000 kN
- Vehicle mass (kg): 400000 kg
- Surface gravity g (m/s²): Earth (9.80665)
- Answer
- Thrust-to-weight ratio T/W: 1.530
- Upward acceleration at liftoff: 5.19 m/s²
- Check
- With T/W = 1 the net acceleration is exactly zero (the vehicle just hovers); the build checks this.
Assumptions
Liftoff instant, vertical flight, no drag. Gravity values: Earth 9.80665 (standard), Moon 1.62, Mars 3.71 m/s² (NASA planetary fact sheets).
Go deeper
Sources
- J. D. Mattingly, Elements of Propulsion: Gas Turbines and Rockets, AIAA, 2006.
- H. D. Curtis, Orbital Mechanics for Engineering Students, 4th ed., Butterworth-Heinemann (Elsevier), 2020.
- NASA JPL Solar System Dynamics, planetary physical parameters.
- NASA NSSDCA, Planetary Fact Sheets.