Battery life calculator
Estimate how long a battery will run your project from its capacity in mAh and the current your circuit draws. Switch to sleep-and-wake mode to estimate battery life for low-power IoT and sensor boards.
Enter your values
Roughly how long will a battery run your project? Use a constant load, or a sleep-and-wake pattern for IoT boards.
Result
Hours = mAh × usable% ÷ mAAvg = Iawake × d + Isleep × (1 − d)Coro's tip: This is an estimate. Cold weather, high currents and old cells all give less. Measure your real current with a multimeter for a better answer.
Battery life calculator: common questions
How do I calculate battery life?
Divide the usable capacity by the load current: hours = mAh × usable % ÷ mA. A 2000 mAh battery at 80% usable powering 50 mA lasts about 32 hours.
Why use less than 100% of the capacity?
Regulator losses, the cut-off voltage of your circuit, temperature and battery age all reduce what you can actually use. 70–85% is a realistic estimate.
How do I estimate battery life with sleep mode?
Work out the average current: Iavg = Iawake × awake fraction + Isleep × (1 − awake fraction), then divide the capacity by that average.
For learning and low-voltage hobby circuits (12 V and below). Always check the part's datasheet. Never use these tools to plan mains (230 V) wiring.