Verify before flight. Check the POH/AFM for aircraft-specific limits and performance.
Performance
Climb Gradient to FPM Calculator
Convert climb gradient in feet per nautical mile (ft/NM) to required feet per minute (FPM) using groundspeed.
ft/NM
kt
Vertical speed—
Gradient percent—
NM/min—
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200 ft/NM at 90 knots
A 200 ft/NM gradient at 90 kt groundspeed requires 200 × (90 / 60) = 300 fpm. At 120 kt it requires 400 fpm.
More groundspeed requires more vertical speed for the same gradient. Compare with aircraft capability at the actual weight, altitude and temperature.
Formula and method
Vertical speed (ft/min) = climb gradient (ft/NM) × groundspeed (NM/min).