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Descent Rate Calculator

Work out descent rate instantly with clear inputs, formula shown and shareable results.

About Descent Rate Calculator

Descent rate follows from the geometry: the required gradient is altitude divided by distance, and the rate in feet per minute is that gradient multiplied by ground speed in nautical miles per minute. The familiar 3 degree profile is about 318 ft per nautical mile, or roughly five times ground speed in knots.

Formula

Descent rate

ROD = (altitude / distance) x GS / 60; angle = atan(ft per nm / 6076.12)

Worked example

With the default values below, Descent Rate Calculator returns Rate of descent required of 1,260. Change any input above and every figure here is recalculated in your browser.

Inputs used

Altitude to lose
9,000 ft
Distance available
25 nm
Ground speed
210 kt

Results

Rate of descent required
1,260 ft/min
Gradient
360 ft/nm
Descent angle
3.39 °
Time in descent
7.14 min

Step by step

  1. 1Values used
  2. 2Descent rate
  3. 3Rate of descent required= 1,260 ft/min
  4. 4Gradient= 360 ft/nm
  5. 5Descent angle= 3.39 °
  6. 6Time in descent= 7.14 min

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 2 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

What is the 'times five' rule?

For a 3 degree path, rate of descent in ft/min is approximately ground speed in knots multiplied by five — 700 ft/min at 140 kt.

Does wind change the required rate?

Yes. A tailwind raises ground speed, so the same 3 degree path needs a higher rate of descent in ft/min.

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Descent Rate Calculator – Calculate Rate of descent required