Free Specific Impulse Calculator

Calculate the specific impulse of a rocket engine: Isp = ve / g0, the exhaust velocity normalised by standard gravity.

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m/s

Specific Impulse

305.91 s

Thrust per Flow Rate3,000.00 N/(kg/s)

Specific Impulse vs Exhaust Velocity

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Specific Impulse

Specific impulse (Isp) measures rocket engine efficiency: how much thrust per unit weight of propellant consumed per second.

Formula

Isp = ve / g0

  • *ve* = effective exhaust velocity (m/s)
  • *g0* = 9.80665 m/s2 (standard gravity)

    • Higher Isp means more efficient use of propellant. Chemical engines: 200-450 s. Ion engines: 1500-5000 s.

    Example Calculation

    Engine with exhaust velocity 3000 m/s.

    1. 01Isp = ve / g0
    2. 02Isp = 3000 / 9.80665
    3. 03Isp = 305.9 s

    Frequently Asked Questions

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