How This Drone Flight Time Calculator Works
The calculator turns your battery size into energy, then divides it by the power your drone needs to hover. First it works out usable energy in watt-hours: capacity in amp-hours, times voltage, times the share of the battery you're willing to use. Then it estimates hover power from the all-up weight and a "watts per kilogram" figure that reflects how efficient your drone is.
Flight time (minutes) = usable Wh ÷ average watts × 60
Finally, it shows a "realistic mixed flying" figure at 85 percent of hover time, because climbing, fast forward flight and wind all draw more power than a gentle hover.
Worked Example
A 5000 mAh, 15.4 V battery holds 77 Wh. Using 80 percent gives 61.6 Wh. A 0.9 kg drone at 170 W/kg needs about 153 W to hover. That's 61.6 ÷ 153 × 60, or roughly 24 minutes of hover, and about 20 minutes of mixed flying.
Choosing the Right Watts per Kilogram
This is the number that makes the biggest difference. Large, slow-spinning propellers are efficient, so folding camera drones often sit between 130 and 170 W/kg. Small FPV quads and heavy-lift drones with smaller props work harder, typically 180 to 250 W/kg. If you know your real average current from flight logs, you can tune this value until the result matches.
Ways to Get More Flight Time
- Remove unnecessary accessories like prop guards when you don't need them.
- Fly smoothly and avoid long climbs at full throttle.
- Keep batteries warm in winter.
- Look after your packs with our battery life tips.
Next, use the drone range calculator to plan a safe distance, or read drone specs explained to see why advertised times are always higher.
FAQ
Frequently Asked Questions
How is drone flight time calculated?
Flight time is the usable battery energy divided by the power the drone needs to stay in the air. Usable energy is capacity times voltage times the share you are willing to use, and power rises with total weight.
Why does adding payload reduce flight time so much?
Hover power grows faster than weight. Adding 20 percent more weight typically costs more than 20 percent of flight time, because the motors must work harder and run less efficiently.
What battery reserve should I keep?
Land with about 20 to 30 percent left. That covers wind on the way home, cold-weather voltage drop and any delay landing. This calculator uses 80 percent usable capacity by default.
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