Estimate flight time by dividing usable battery capacity by the aircraft’s total average current. When changing batteries, update both capacity and all-up mass, then compare under the same flight conditions.
1. Calculate endurance from usable capacity
Flight time (minutes) = usable capacity (Ah) ÷ total average current (A) × 60. Divide capacity in mAh by 1,000 to convert it to Ah.
Using 80% of a 5,000 mAh pack gives 4 Ah. At an average of 21 A, 4 ÷ 21 × 60 gives about 11.4 minutes. The 80% fraction is an example assumption. Set usable capacity for battery condition, load, operating voltage limits and the reserve you need.
For a power-based calculation, use usable energy (Wh) ÷ average power (W) × 60. Capacity in mAh alone cannot compare batteries at different voltages.
This site’s flight-time calculator estimates power from all-up mass and the propulsion inputs of the selected model. The average-current examples below explain the calculation; the calculator does not offer a direct measured-current input.
2. Separate hover, cruise and climb
Hover requires thrust to support weight; climbing also requires energy to gain altitude. Cruise power depends on speed, airframe drag and rotor operating conditions. Cruise does not always draw less current than hover.
To find the mission average, multiply current by duration for each segment, add the results and divide by total duration. The following hypothetical mission is a calculation example, not measured aircraft performance.
| Segment | Assumed total current | Duration | Consumption |
|---|---|---|---|
| Climb | 30 A | 1 min | 0.5 Ah |
| Hover | 21 A | 6 min | 2.1 Ah |
| Cruise | 18 A | 3 min | 0.9 Ah |
Total consumption is 3.5 Ah. Average current is (30 × 1 + 21 × 6 + 18 × 3) ÷ 10 = 21 A. That average supports the earlier 11.4-minute estimate when the same mission proportions are assumed.
To explore the airflow behind the cruise-power discussion, open the quadcopter wake visualization sample.
3. Include the weight of the larger battery
A larger battery stores more energy, but the heavier aircraft requires more thrust. Update battery capacity, cell count and total mass including the new pack in the calculator.
This comparison assumes the same voltage and an 80% usable fraction. Both mass and average current are illustrative inputs; current here is not calculated from mass alone. Use candidate-specific estimates or measured current for an actual comparison.
| Battery capacity | All-up mass | Average current | Estimated time |
|---|---|---|---|
| 5,000 mAh | 2.00 kg | 21 A | 11.4 min |
| 6,000 mAh | 2.25 kg | 25 A | 11.5 min |
| 7,000 mAh | 2.50 kg | 30 A | 11.2 min |
6 Ah × 0.8 ÷ 25 A × 60 = 11.52 minutes. Under these assumptions, 20% more capacity produces almost no endurance gain. After accounting for battery mass, recheck thrust margin and current ratings.
4. Refine average current with flight logs
Read elapsed time and the change in consumed capacity for the relevant flight segment. For example, 2,800 mAh consumed over 8 minutes gives 2.8 ÷ (8 ÷ 60) = 21 A. Separate ground-idle consumption from the flight interval.
If the initial assumption was 18 A, 4 Ah would predict 13.3 minutes. Replacing it with the logged average of 21 A gives 11.4 minutes. Compare records with similar batteries, payloads, speeds and wind conditions.
Check current-sensor calibration before treating logs as a reference. ArduPilot documents comparison with an ammeter or comparison of logged consumption with recharge capacity. Enter actual mass and propulsion conditions in the calculator, then compare its result with the estimate based on measured average current.
Questions and answers
Does doubling battery capacity double flight time?
Only if average current and the usable fraction stay unchanged. In an aircraft, extra battery mass changes thrust requirements and current consumption. Update all-up mass before comparing packs.
Can I fly half the calculated maximum range and return?
The calculator derives theoretical range from cruise time and speed. Climb, landing, waiting, different winds on each leg and battery reserve need separate allowances, so half that distance is not an operating radius.