Jet Engine Thrust Calculator

Jet Engine Thrust Formula

Worked Example

A turbojet with 50 kg/s of air, f = 0.02, flying at 250 m/s with a 600 m/s jet:

1. Core: F = ṁₐ[(1 + f)vₑ − V₀] = 50 × [1.02 × 600 − 250] = 18100 N
2. η_p = FV₀ ÷ ΔKE = 59.40269117 %

TSFC: 55.24861878 mg/(N·s) · Specific thrust F/ṁₐ: 362 N·s/kg · Propulsive efficiency: 59.40269117 % · Thermal efficiency: 17.71511628 % · Overall efficiency: 10.52325581 %

GATE tip

For a ramjet or turbojet with f ≪ 1, propulsive efficiency reduces to 2V₀/(vₑ + V₀). Afterburning raises vₑ and thrust but lowers propulsive efficiency and raises TSFC.

More Propulsion Calculators

• Axial Compressor Stage Calculator

  w = U(C_θ2 − C_θ1), ΔT₀ = w/c_p

  π = (1 + ηΔT₀/T₀₁)^(γ/(γ−1)); R = 1 − (C_θ1 + C_θ2)/(2U)

  Example: A stage with U = 300 m/s turning the whirl from 100 to 200 m/s at 288 K inlet and 88 % efficiency: Stage pressure ratio = 1.35711.

  Open the axial compressor stage calculator →

• Rocket Equation Calculator

  Δv = I_sp g₀ ln(m₀ / m_f)

  m₀ initial (wet) mass, m_f final (dry) mass, g₀ = 9.80665 m/s², vₑ = I_sp g₀

  Example: A stage with I_sp = 350 s burning from 100 t to 10 t: Delta-v Δv = 7903.23 m/s.

  Open the rocket equation calculator →

• Rocket Thrust Calculator

  F = ṁvₑ + (pₑ − pₐ)Aₑ

  I_sp = F/(ṁg₀); effective exhaust velocity c = F/ṁ

  Example: 250 kg/s at 3000 m/s, exit pressure 70 kPa, 0.8 m² exit at sea level: Thrust F = 724.94 kN.

  Open the rocket thrust calculator →

Frequently asked questions

Sources

• The International System of Units (SI), 9th edition (SI Brochure), Bureau International des Poids et Mesures .

Last reviewed: 2026-10-15. Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.