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    Rocketry

    Thrust-to-Weight Ratio Calculator

    Can your rocket lift off? Thrust-to-weight ratio on Earth, the Moon, Mars or any body.

    TWR = F / (m · g)

    Inputs

    Results

    Thrust-to-weight ratio
    1.414
    Net initial vertical acceleration
    4.0561 m/s²
    Weight on Earth
    5,380.2 kN
    • TWR above 1: the vehicle can lift off vertically.
    • Launch vehicles typically lift off with TWR around 1.2–1.5.
    Worked solution
    1. Weight = 549,000 kg × 9.8 m/s² = 5,380,200 N
    2. TWR = 7,607,000 / 5,380,200 = 1.414

    How the result changes

    Net acceleration (m/s²) plotted against Vehicle mass (tonnes), from one quarter to four times your input, with your input marked.020405001,0001,5002,000Vehicle mass (tonnes)Net acceleration (m/s²)your input
    Net acceleration vs vehicle mass

    How it works

    A ratio above 1 means engines push harder than gravity pulls. As propellant burns off the ratio climbs, which is why astronauts feel acceleration rise toward the end of a stage.

    Variables

    • F — total engine thrust
    • m — vehicle mass
    • g — local gravitational acceleration

    Assumptions and limits

    • Thrust and mass at the instant of lift-off
    • Ignores drag; sea-level thrust should be used for launches through an atmosphere

    For education only. These models are simplified and are not suitable for spacecraft navigation or safety-critical engineering. See our scientific accuracy policy.