Departure

When requested to climb by ATC, the pilot should initiate the climb promptly at an optimum rate consistent with the operating characteristics of the aircraft to 1,000' below the assigned altitude then 500 to 1,500 fpm.

—Sporty's

Convert ground speed to nautical miles per minute

divide ground speed by 60 = miles/min

multiply by desired climb rate: 400 ft/NM * miles/min

or ground speed by ft/NM divide by 60)

—Gold Seal