Climb Gradient Converter
Climb gradient in percent, ft per nm and ft per minute at your ground speed, and the gradient an obstacle needs with the clearance you choose.
One gradient in all three forms (and metres per kilometre and per minute), the rate of climb it needs at a ground speed, and whether it clears an obstacle of a given height and distance by your margin.
Example: 3.3 % at 100 kt ground speed is 200 ft/nm and 334 ft/min; a 500 ft obstacle 2 nm out with 35 ft clearance needs 268 ft/nm, so this climb reaches only 401 ft there and does not clear it.
Percent, per mile,
per minute.
How the three ways of stating a climb relate, why ground speed and not airspeed ties gradient to rate, how the obstacle check is done, and what the aircraft must supply.
Three forms of one gradient
A gradient is height gained per distance travelled: a percentage, or feet per nautical mile (percent × 60.76, since a nautical mile is 6,076 ft). At a ground speed in knots — nautical miles per hour — the rate of climb in feet per minute is feet per nautical mile × ground speed ÷ 60. A departure procedure publishes the gradient; the aircraft produces a rate; the page converts between them.
Ground speed, not airspeed
Distance over the ground is what the gradient is measured against, so a headwind — lower ground speed for the same rate of climb — steepens the gradient actually flown, and a tailwind flattens it. Use the ground speed you expect in the climb, at the climb airspeed.
The obstacle
An obstacle at a height and distance needs a gradient of (height + clearance) ÷ distance to clear it by that margin; the page compares your gradient with it and gives the height you would have at the obstacle. Distance is measured from wherever the climb is taken to start; a published procedure states its own reference.
What the number does not settle
The rate of climb an aircraft achieves at a weight, temperature, altitude and configuration is a handbook figure; this page converts gradients, it does not predict performance. Published procedure gradients carry their own clearances and rules. A planning aid, not a substitute for the pilot’s operating handbook, the aircraft’s limitations or the rules that apply to the flight. Inputs stay in your browser; the same anonymous usage counts as the rest of the site apply.