Climb Gradient Calculator – ft/NM to Feet per Minute
This climb gradient calculator converts a required climb gradient in ft/NM or percent into the rate of climb you need at your ground speed, and shows how long a climb will take.
Use ground speed, not indicated or true airspeed. A headwind lowers ground speed and so lowers the rate of climb needed for the same gradient.
For training and general informational use. Confirm climb performance with the approved aircraft flight manual.
Turn a published climb gradient into a rate of climb
Departure procedures state climb requirements as a gradient, such as 200 ft per nautical mile or 3.3%. The vertical speed indicator shows feet per minute. This calculator converts one into the other at your ground speed, so you can check before departure that the aircraft can meet the requirement on the day.
How to use it
- Enter the required gradient from the departure procedure or obstacle data.
- Choose whether it is in feet per nautical mile or percent.
- Enter the expected ground speed during the climb.
- Optionally enter the altitude to gain to see the time and distance needed.
Method and calculation
Rate of climb (ft/min) = gradient (ft/NM) × ground speed (kt) ÷ 60. A percent gradient is converted using 1 NM = 6,076 ft, so 1% equals about 60.8 ft/NM. Time to climb is altitude ÷ rate of climb, and the distance covered is time × ground speed.
Worked example and practical notes
The standard instrument departure gradient of 200 ft/NM at a ground speed of 120 kt needs 200 × 120 ÷ 60 = 400 ft/min. A published gradient of 350 ft/NM at the same ground speed needs 700 ft/min, which some light aircraft cannot achieve on a hot day.
Accuracy and practical tips
Climb performance falls as density altitude rises, so check the aircraft’s achievable rate of climb at the actual temperature, pressure altitude and weight. Plan with the slowest likely ground speed for the gradient check only if your aircraft’s climb rate stays constant; otherwise use the flight manual climb data.
Formula consistent with the rate-of-climb tables published in FAA Terminal Procedures Publications. Climb gradients and departure procedures are explained in the FAA Instrument Procedures Handbook. Use approved performance data for operational decisions.
Last reviewed: October 2026
Read the guide: Climb Gradient Explained: ft/NM, Percent and ft/min
Frequently asked questions
What is the standard climb gradient?
Under FAA TERPS and ICAO PANS-OPS, the standard minimum is 200 ft/NM, about 3.3%, unless a higher gradient is published for obstacles or airspace.
How do I convert percent to ft/NM?
Multiply the percent by about 60.76. For example, 3.3% is roughly 200 ft/NM and 5% is about 304 ft/NM.
Why does ground speed matter?
The gradient is height per distance. The faster you cover the ground, the faster you must climb to gain the same height in each nautical mile.
Does a headwind help the climb gradient?
Yes. A headwind reduces ground speed, so the same rate of climb gives a steeper gradient over the ground.