Thrust Calculator

Calculate rocket, jet, mass flow, and static propeller thrust from exhaust velocity, mass loss, RPM, diameter, pitch, and air density.

Choose a tab, enter values, then calculate.

Rocket / Jet

Mass Flow

Propeller Static

Rocket thrust equation

Effective exhaust velocity

Flow area at nozzle

Mass loss rate

Mass expelled

Elapsed time

Ambient pressure

Pressure at nozzle

Simple thrust from velocity and mass flow

Velocity

Change in mass

Change in time

Thrust force

Static propeller thrust estimate

Propeller diameter

Pitch

Propeller type

Effectiveness coefficient CF

Number of blades

RPM

Air temperature

Air density

Tip speed above 230 m/s is usually inefficient, and near 320 m/s approaches sonic risk.

Thrust Formula

The following formula is used to calculate the thrust force produced by a rocket engine.

T = ṁ V_e + (P_e − P_a) A_e

ṁ – propellant mass-flow rate (kg/s)
V_e – effective exhaust (exit) velocity relative to the rocket (m/s)
P_e – static pressure at the nozzle exit (Pa)
P_a – ambient (back-) pressure (Pa)
A_e – exit area of the nozzle (m²)

Thrust Definition

Thrust is the force produced by an engine (such as a rocket or jet) when it expels mass as exhaust. For a rocket nozzle, thrust includes both the exhaust momentum term (ṁV_e) and the nozzle pressure-difference term (P_e − P_a)A_e.

Thrust Example

How to calculate thrust?

First, determine the exhaust velocity.
Use the effective exhaust (exit) velocity Vₑ relative to the rocket (or use an Isp preset to compute Vₑ = Isp×g₀).
Next, determine the propellant mass flow.
Measure the propellant mass used (Δm) over a burn time (Δt), then compute ṁ = Δm/Δt.
Next, determine the pressure/area terms.
Find the nozzle exit pressure Pₑ, ambient pressure Pₐ, and nozzle exit area Aₑ (or set Pₑ = Pₐ to neglect the pressure-thrust term).
Finally, calculate the thrust.
Compute T = ṁVₑ + (Pₑ − Pₐ)Aₑ.

FAQ

What is thrust?

Thrust is the force produced by an engine when it expels mass (exhaust). For rocket nozzles, it includes both the exhaust momentum term and (when applicable) a nozzle pressure-difference term.