Manufacturers’ flight times are often measured in ideal conditions. This calculator estimates hover time from the basics: how much energy the battery holds and how much power the drone needs to stay in the air.
Power needed to hover
A multirotor’s hover power is roughly proportional to its weight. Typical values:
- about 100 W per kg for efficient camera drones with large, slow propellers;
- about 150 W per kg for typical hobby multirotors;
- about 250 W per kg or more for racing quads and heavily loaded drones.
A 1.2 kg drone at 150 W per kg needs about 180 W. Wind, fast flying and aggressive maneuvers all increase it.
Current and battery
Lithium polymer cells have a nominal voltage of about 3.7 V. A 4S pack (4 cells in series) gives about 14.8 V.
current = power ÷ voltage = 180 ÷ 14.8 ≈ 12.2 A
Flight time
Do not drain a LiPo below about 20% of its capacity: deep discharges damage cells and the voltage sags as they empty. Using 80% of a 5,000 mAh pack:
flight time = capacity (Ah) × usable share ÷ current × 60 = 5 × 0.8 ÷ 12.2 × 60 ≈ 20 minutes
Adding a bigger battery adds weight too, so flight time grows less than capacity. Beyond a point, a heavier pack barely helps.
Battery energy and travel
Battery energy in watt-hours is capacity (Ah) × voltage: 5 × 14.8 = 74 Wh. Airlines generally allow spare lithium batteries under 100 Wh in carry-on luggage, 100 to 160 Wh with the airline’s approval, and forbid larger ones on passenger flights. Spare batteries are not allowed in checked bags.
Rules for flying in the US
- Drones of 250 g (0.55 lb) or more must be registered with the FAA, even for recreational use, and need to broadcast Remote ID.
- Recreational flyers must pass the free TRUST online test.
- Fly below 400 ft, keep the drone in sight, and do not fly over people or near airports without authorization.
Getting more flight time
- Keep the drone light: remove unnecessary accessories.
- Use efficient, larger propellers matched to the motors.
- Fly smoothly and avoid windy days.
- Keep batteries warm in cold weather; LiPos lose capacity when cold.
- Store LiPos at about 3.8 V per cell when not flying for more than a few days.