Why is real flight time less than calculated?

You should never fully discharge a LiPo battery as it damages the cells and can be dangerous, so most pilots use only 80% of capacity (the Usable Capacity setting). Current draw also varies with manoeuvres, wind and throttle changes, which the efficiency factor accounts for. The "Reserve + losses buffer" result is the gap between the theoretical maximum (100% capacity, no losses) and the usable time — it combines the 20% capacity reserve with the efficiency derating, so it is larger than the capacity reserve alone.

How do I measure average current draw?

Use a watt meter inline between the battery and ESC during a typical flight or run. Many ESCs also log average current. Alternatively, check the motor specification for current draw at your voltage and propeller combination.

What is a safe LiPo discharge level?

Do not discharge below 3.5V per cell under load (3.7V resting). Most pilots set a timer or voltage alarm at 80% of capacity used. Over-discharging below 3.0V per cell causes permanent damage and can lead to puffing or fire.

Does throttle percentage affect flight time linearly?

Not exactly. Current draw increases more than linearly with throttle due to motor and propeller characteristics. At 50% throttle you typically draw 30-40% of full-throttle current. This calculator uses throttle as a linear approximation for average flying.

ModelCalcs

Battery Flight Time Calculator

Calculate estimated flight or run time from battery capacity, motor current draw and efficiency.

Battery Capacity

Battery capacity in milliamp-hours

Average Current Draw

Average motor current at full throttle

Battery VoltageNominal battery voltage (cell count)

Model TypeSeeds a typical efficiency factor (planes/cars 0.90, helis/quads 0.85). Override in Advanced Options.

Average Throttle

Average throttle during typical use

How We Calculate This

Flight Time Formula

Theoretical max = Battery capacity (mAh) ÷ (Average current (A) × 1000) × 60

Usable time = Theoretical max × Usable capacity % × Efficiency factor

The usable capacity (default 80%) prevents over-discharging the LiPo. The efficiency factor accounts for real-world losses from wind, manoeuvres and throttle variation — choosing a Model Type seeds a typical value (planes/cars 0.90, helis/quads 0.85), which you can override in Advanced Options.

The Reserve + losses buffer is the difference between the theoretical max and the usable time, so it bundles the unused 20% capacity reserve with the efficiency derating. Land or recharge before the usable time is reached.

Energy = Capacity (Ah) × Nominal voltage (Wh); Power draw = Effective current × Voltage (W). LiPo nominal voltage is 3.7 V per cell (3S = 11.1 V).

Frequently Asked Questions

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Last updated: March 2026

All calculations are estimates. Always verify quantities before purchasing materials.