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Thrust Required Calculator

Work out thrust required instantly with clear inputs, formula shown and shareable results.

About Thrust Required Calculator

In steady flight thrust equals drag, and drag equals weight divided by the lift-to-drag ratio. Climbing adds a thrust requirement equal to weight times the climb gradient, since the engines must also lift the aircraft against gravity at that rate.

Formula

Thrust required

T = W/(L/D) + W x gradient; T/W = thrust required / weight

Worked example

With the default values below, Thrust Required Calculator returns Thrust required of 68.35. Change any input above and every figure here is recalculated in your browser.

Inputs used

Aircraft weight
68,000 kg
Lift-to-drag ratio
16 :1
Climb gradient
4 %

Results

Thrust required
68.35 kN
Drag in level flight
41.68 kN
Extra thrust for the climb
26.67 kN
Thrust-to-weight ratio
0.1025

Step by step

  1. 1Values used
  2. 2Thrust required
  3. 3Thrust required= 68.35 kN
  4. 4Drag in level flight= 41.68 kN
  5. 5Extra thrust for the climb= 26.67 kN
  6. 6Thrust-to-weight ratio= 0.1025

Assumptions and limits

  • The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
  • Aviation results are planning estimates only. Always verify take-off, landing, fuel, weight and balance figures against the certified Aircraft Flight Manual, current performance charts and applicable aviation regulations before flight.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Aviation results are planning estimates only. Always verify take-off, landing, fuel, weight and balance figures against the certified Aircraft Flight Manual, current performance charts and applicable aviation regulations before flight.

Frequently Asked Questions

Why is thrust just weight over L/D?

In level flight lift equals weight and thrust equals drag. Since L/D = lift/drag, drag must be weight divided by L/D.

Does a steeper climb need proportionally more thrust?

Yes, almost linearly for shallow gradients: each 1% of gradient adds 1% of weight to the thrust requirement.

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