Drone Flight Time Calculator
Estimate a drone’s flight time from its battery capacity, usable charge and average current draw — plus the pack’s power delivery.
How it works
Usable capacity (Ah) = mAh ÷ 1000 × usable % · Flight time (min) = usable Ah ÷ average current (A) × 60 · Power = voltage × current · C-rate = current ÷ capacity(Ah)
Flight time is just usable charge divided by how fast you draw it. A battery’s full capacity is never all available — flying a LiPo below about 20% state of charge damages it, so only around 80% is usable in practice. Average current is the crucial and hardest number: gentle cruising might pull a fraction of the aggressive-flying figure, so this estimate is only as good as the current you enter. Heavier payloads, wind and acrobatic flying all raise current and cut time.
Worked example
A 5,000 mAh 6S pack flown to 80% usable is 5 × 0.8 = 4 Ah. At a 15 A cruise average, flight time is 4 ÷ 15 × 60 = 16 minutes. Power draw is 22.2 V × 15 A ≈ 333 W, and the discharge rate is 15 ÷ 5 = 3C.
Frequently asked questions
Why is only 80% of the capacity usable?
Lithium-polymer packs are damaged by deep discharge, so pilots land with roughly 20% remaining. Using 80% as usable capacity keeps the estimate realistic and your battery healthy — lower the figure if you land with a larger reserve.
How do I find the average current draw?
The best source is telemetry or a power meter logged over a real flight — divide the milliamp-hours consumed by the flight time in hours. Hovering pulls far less than aggressive flight, so use an average that matches how you actually fly.
What is the C-rating and does it matter here?
The C-rate is current relative to capacity (a 5 Ah pack at 15 A is 3C). Your battery must be rated for at least the peak C-rate you draw, or it will sag and overheat. It does not change flight time directly but caps how much current you can safely pull.
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This calculator is for educational purposes. Double-check important results before acting on them.