Specific Impulse Calculator

Free calculate specific impulse (isp), exhaust velocity, and thrust efficiency for rocket engines. determine isp from thrust, mass flow rate, and exhaust velocity.

Input Parameters

Results

Enter parameters to calculate specific impulse

Specific Impulse Formulas

Specific Impulse

Isp = F / (ṁ × g₀)

Where:

  • • Isp = specific impulse (s)
  • • F = thrust (N)
  • • ṁ = mass flow rate (kg/s)
  • • g₀ = standard gravity (9.80665 m/s²)

Exhaust Velocity

vₑ = Isp × g₀

Common Isp Values

  • • Chemical rocket: 200-450 s
  • • Ion thruster: 2000-5000 s
  • • Hall thruster: 1000-2000 s
  • • Nuclear thermal: 800-1000 s

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