Everyday Life calculator
Battery Life Calculator
Estimate battery runtime from capacity, current draw, and efficiency.
Formula
Battery runtime
Battery runtime varies with voltage, temperature, age, load spikes, and device power management.
Runtime hours = battery mAh x efficiency / load mA
5,000 mAh at 500 mA and 85% efficiency lasts about 8.5 hours.
FAQs
Why include efficiency?+
Real batteries and converters do not deliver all rated capacity to the device.
Can I use this for power banks?+
Yes, but account for output voltage conversion losses.
How does the Battery Life Calculator calculate the result?+
It uses the Battery runtime: Runtime hours = battery mAh x efficiency / load mA. 5,000 mAh at 500 mA and 85% efficiency lasts about 8.5 hours.
What information do I need to use the Battery Life Calculator?+
Estimate battery runtime from capacity, current draw, and efficiency.
How accurate is the Battery Life Calculator?+
Battery Life Calculator applies the formula and assumptions shown on this page. Results may be rounded for readability, so verify changing rates, thresholds, medical guidance, or legal rules with the cited source or a qualified professional.
What should I check before using the Battery Life Calculator result?+
Check that the units, dates, rates, and assumptions match your situation. Change one input at a time to understand which values have the largest effect on the result.
Everyday Life guide
How to use the Battery Life Calculator
Estimate battery runtime from capacity, current draw, and efficiency. The page also explains the battery runtime and shows a practical example: 5,000 mAh at 500 mA and 85% efficiency lasts about 8.5 hours.
- 1
Enter your details
Enter capacity, current draw, and efficiency, then complete any other fields shown in the calculator.
- 2
Check the calculation
Review the result alongside the battery runtime: Runtime hours = battery mAh x efficiency / load mA.
- 3
Compare scenarios
Change one or more inputs to see how they affect the battery Life Calculator result before you use the estimate.
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