This calculator estimates the battery-limited flight runtime of an inspection drone from usable battery energy, average flight power, a landing reserve, and any separate payload electrical load. It can help when checking mission duration, planning battery rotation, or comparing inspection payload configurations.
The calculation is an energy-balance estimate rather than a certified endurance value. Actual power demand changes with aircraft mass, wind, speed, climb rate, hovering, temperature, propeller condition, flight-control behavior, and mission profile. Cameras or sensors that draw power from the flight battery can also reduce endurance, which is why a separate payload-load field is provided. A reserve prevents the model from treating the entire battery as expendable. Operational flight planning should remain within manufacturer guidance and applicable aviation procedures, and should use measured consumption from representative missions when available.
Flight energy assumptions
Wh
W
%
W
Result
—
estimated flight runtime
Energy available before reserve—
Total average power—
Runtime in seconds—
1. Enter usable battery energy Use watt-hours available to the aircraft, preferably after battery-management limits rather than a raw cell calculation.
2. Enter average flight power Use the average propulsion and aircraft power draw expected during the inspection mission.
3. Set a landing reserve Enter the battery percentage you want remaining rather than available for planned flight time.
4. Add payload electrical load Enter camera, lighting, sensor, or compute power drawn from the same flight battery if it is not already included.
5. Review runtime The main result is estimated minutes to the reserve threshold, with energy and power details alongside it.
Available flight energy = Battery energy × (1 − Reserve %)
Total average power = Average flight power + Payload electrical load
Runtime (hours) = Available flight energy ÷ Total average power
Runtime (minutes) = Runtime hours × 60
Watt-hours divided by watts gives hours. The model assumes the entered power values are representative averages across the mission.
What the result means
The result estimates flight minutes available before the selected reserve is reached at the entered average power demand.
Wind, cold temperatures, heavier payloads, aggressive flight, battery aging, and required return-to-home margin can all reduce usable mission time.
Given:
Usable battery energy: 260 Wh
Average flight power: 560 W
Landing reserve: 25%
Payload electrical load: 40 W
Calculation:
Available energy = 260 × (1 − 0.25) = 195 Wh. Total average power = 560 + 40 = 600 W. Runtime = 195 ÷ 600 = 0.325 hours = 19.5 minutes.
Result: About 19.5 minutes.
Interpretation: At a 600-watt average load, the drone would reach the 25% reserve after roughly nineteen and a half minutes under the simplified model.
Should I use battery voltage and amp-hours instead?
If watt-hours are not listed, nominal watt-hours can be estimated from voltage multiplied by amp-hours. Usable energy can still be lower because of battery-management limits, voltage sag, and reserve policy.
Is the landing reserve the same as a regulatory requirement?
No. It is a planning input in this calculator. Required reserves and operating procedures depend on aircraft, manufacturer guidance, mission, operator procedures, and applicable rules.
Why does payload power matter if the payload also adds weight?
This field captures only the payload’s electrical draw from the flight battery. Added mass can increase propulsion power too, so the average flight-power input should reflect the actual payload configuration.
Can I use hover power as average flight power?
Only if the mission is dominated by hovering and that measurement is representative. Forward flight, wind, climbs, and repeated repositioning can produce a different average load.
How should I plan a mission from the runtime result?
Treat the value as an energy estimate, not the full usable mission duration. Deduct time for takeoff, transit, return, contingencies, and any additional reserve required by your procedures.