1. Calculate Your Battery Life
Enter your battery and device details below to get an instant estimate. This tool helps you plan your projects, from simple LEDs to complex robotics.
To preserve battery health, it's recommended not to fully discharge it. 80% is a common value.
Estimated Battery Life
Enter values to see the estimate.
Discharge Visualization
This chart illustrates how the battery capacity decreases over its estimated runtime.
2. Understand the Concepts
Calculators are great, but understanding the principles behind them is even better. Explore the tabs below to become a battery expert and learn why your real-world results might differ from the estimate.
The Basic Formula
The calculation for battery life is fundamentally simple. It's the total capacity of the battery divided by the average current drawn by the device.
A Practical Example:
Let's say you have a 3000 mAh battery and your device consumes 50 mA on average.
- Convert Units: First, ensure your units are consistent. We need Amps (A) and Amp-hours (Ah).
- 3000 mAh = 3 Ah (since 1000 mAh = 1 Ah)
- 50 mA = 0.05 A (since 1000 mA = 1 A)
- Calculate: Now, apply the formula.
- 3 Ah / 0.05 A = 60 Hours
How to Prepare Reliable Battery-Life Inputs
Battery runtime is an engineering estimate, not a fixed promise. Prepare inputs in compatible units: milliamp-hours divided by milliamps gives hours, just as amp-hours divided by amps does. For a changing load, calculate average current with Iavg = Σ(Ii × ti) / T, including sleep, active, radio, indicator, regulator quiescent, and sensor states.
- Capacity: use capacity available at the expected discharge rate and cutoff voltage, not only the label value.
- Derating: account for temperature, aging, self-discharge, and conversion losses.
- Pulse loads: confirm that battery resistance and wiring do not pull voltage below the device cutoff.
- Interpretation: treat the calculated value as a planning baseline; verify it with a representative duty cycle and end-of-life battery.
