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Instrument departures, missed approaches and some visual departures specify a minimum climb gradient. The chart might say “Minimum climb of 350 ft per NM to 3,000” or show 4.5% in an RNAV procedure. Your vertical speed indicator shows feet per minute. This guide explains what a climb gradient means, how to convert it, and how to check whether your aircraft can meet it before you take off.
For a quick conversion, use our Climb Gradient Calculator.
Climb gradient vs rate of climb
A climb gradient is height gained per distance travelled over the ground. It is expressed in feet per nautical mile (ft/NM) or as a percentage. A rate of climb is height gained per unit of time, normally feet per minute (ft/min or fpm).
Obstacles are fixed to the ground, so procedure designers use gradient. The aircraft, however, delivers a rate of climb. The link between them is ground speed: the faster you cross the ground, the faster you must climb to stay above the same slope.
The formulas
- Rate of climb (ft/min) = gradient (ft/NM) × ground speed (kt) ÷ 60
- Gradient (ft/NM) = rate of climb (ft/min) × 60 ÷ ground speed (kt)
- Percent to ft/NM: multiply by 60.76 (because 1 NM = 6,076 ft)
- ft/NM to percent: divide by 60.76
A handy approximation: 1% is about 60 ft/NM, so 3.3% is about 200 ft/NM.
The standard 200 ft/NM
Unless a procedure states otherwise, both US TERPS and ICAO PANS-OPS assume an aircraft climbs at least 200 ft/NM (about 3.3%) after takeoff. That assumption gives obstacle clearance on standard departures. Where obstacles or airspace need more, a higher gradient is published along with the altitude to which it applies.
| Gradient | 90 kt | 120 kt | 150 kt | 180 kt |
|---|---|---|---|---|
| 200 ft/NM (3.3%) | 300 | 400 | 500 | 600 |
| 300 ft/NM (4.9%) | 450 | 600 | 750 | 900 |
| 400 ft/NM (6.6%) | 600 | 800 | 1,000 | 1,200 |
| 500 ft/NM (8.2%) | 750 | 1,000 | 1,250 | 1,500 |
Values are rates of climb in ft/min at each ground speed.
Checking your aircraft can make it
- Find the requirement on the departure procedure, including the altitude it applies to.
- Estimate ground speed in the climb. Start with the climb airspeed, convert to true airspeed for the altitude and temperature with our True Airspeed Calculator, then apply the wind.
- Convert the gradient to ft/min at that ground speed.
- Compare with the flight manual rate of climb for the actual weight, pressure altitude and temperature. On a hot day at a high airfield, climb performance can fall a long way; check the density altitude first.
- Keep a margin. Book figures are for a new aircraft flown precisely. Turbulence, a slightly rough engine or a less than perfect speed all eat into them.
Worked example
A departure requires 380 ft/NM to 4,000 ft. You will climb at 90 KIAS, which is about 96 KTAS at the altitudes involved, with a 10 kt headwind. Ground speed is about 86 kt.
Required rate of climb = 380 × 86 ÷ 60 = 545 ft/min. If the flight manual shows only 500 ft/min at today’s weight and temperature, you cannot meet the gradient. Options include waiting for cooler air, reducing weight, using a different departure or climbing in a published climb-in-holding pattern if one exists.
Headwind and tailwind
A headwind reduces ground speed, so the same rate of climb produces a steeper gradient over the ground. That is why aircraft take off into wind. A tailwind does the opposite and can turn a comfortable departure into a marginal one.
Descent works the same way
The same maths applies to descents. A 3° glidepath is about 318 ft/NM, which gives the familiar rule of thumb of descent rate ≈ ground speed × 5. Our Descent Rate Calculator handles the reverse case.
Related tools and guides
- Climb Gradient Calculator
- Density Altitude Explained
- Aircraft Weight and Balance
- Holding Pattern Entries Explained
For training and general information. Use approved aircraft performance data and current published procedures for flight.
Sources and further reading
- FAA Instrument Procedures Handbook (FAA-H-8083-16) (departure procedures and climb gradients)
- AIM 5-2, Departure Procedures
- 14 CFR 91.175 and the terminal procedures legend for published climb gradients
Sources checked November 2026. Rules differ between countries and change over time: for real flights, use the current publications of the authority that applies to you, your aircraft flight manual and your operator’s procedures.