How do I measure average current draw?

Use a watt meter inline between battery and ESC to measure current during flight. Alternatively, fly a timed flight and then check how many mAh the charger puts back in. Divide mAh by flight time in hours to get average amps.

Why should I only use 80% of battery capacity?

Discharging a LiPo below 3.3V per cell causes permanent damage. Stopping at 80% of capacity keeps the voltage above the safe minimum and dramatically extends battery lifespan. Some pilots use only 70% for maximum battery longevity.

How does flying style affect flight time?

Gentle cruising uses about 70% of the average current. Aggressive aerobatics can use 140% or more due to sustained high-throttle manoeuvres. Racing uses even more as throttle is nearly always at maximum. Adjust your style to match desired flight time.

What timer should I set on my transmitter?

Set your timer to 80% of the calculated flight time. This gives you a warning with enough remaining capacity to land safely. For example, if calculated flight time is 10 minutes, set the timer to 8 minutes. Always land with some reserve.

ModelCalcs

Flight Time Calculator — Battery Endurance

Estimate flight or run time from battery capacity and average current draw.

Battery Capacity (mAh)

Battery capacity in mAh

Avg Current Draw (A)

Value for avg current draw (a)

Usable Capacity (%)

80% recommended for LiPo health

Flying StyleSelect the style

How We Calculate This

Calculates flight time from usable battery capacity divided by adjusted current draw.

Formula

Usable capacity = Battery mAh x Usable %
Adjusted current = Avg draw x Flying style factor
Flight time (mins) = Usable capacity / (Adjusted current x 1000) x 60
Timer setting = Flight time x 0.8 (safety margin)

Frequently Asked Questions

Related Calculators

Battery Calculator

Calculate battery capacity, C-rating, discharge rate and run time for your RC model.

Motor KV Calculator

Work out motor RPM from KV rating and battery voltage, or find the right KV.

ESC Rating Calculator

Size your electronic speed controller based on motor current draw and battery setup.

Gear Ratio Calculator

Calculate gear ratios, final drive ratio and top speed for RC cars and trucks.

Servo Torque Calculator

Determine the servo torque needed for your control surfaces or steering.

Last updated: February 2026

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