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Descent Rate Calculator

Descent rate and top-of-descent point for a planned altitude loss.

Enter values

Results update as you type.

Result

Rate of descent

743 ft/min

Start descent
25.12 nm before the point
Time to descend
10.77 min
Altitude to lose
8,000 ft
Descent angle
3 °
Rule of thumb (3× altitude)
24 nm
Feet lost per nm
318

About the Descent Rate Calculator

Descent rate and top-of-descent point for a planned altitude loss.

Also known as: top of descent calculator, tod calculator, descent planning, 3 degree descent.

How to use this calculator

  1. Enter current altitude, target altitude, groundspeed, plan by and the other fields.
  2. The result updates instantly as you type — press Calculate (or Enter) at any time.
  3. Review the breakdown shown under the main result.
  4. Use Copy result or Share to save the answer or send a link with your inputs.

Formula

rate = GS × 101.27 × tan(angle) · TOD = altitude ÷ 1000 × 3 nm

Worked example

Using the values pre-filled in the calculator above:

  • Current altitude = 10,000 ft
  • Target altitude = 2,000 ft
  • Groundspeed = 140 knots
  • Plan by: Descent angle
  • Descent angle = 3 °

the calculator returns:

  • Rate of descent: 743 ft/min
  • Start descent: 25.12 nm before the point
  • Time to descend: 10.77 min
  • Altitude to lose: 8,000 ft