Tech calculator
Battery Life Calculator
Estimate how long a battery can supply a steady average load.
Ideal estimate before conversion losses, aging, temperature, and reserve capacity.
Estimated runtime
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How it works
Actual runtime is normally lower because of conversion losses, cutoff voltage, temperature, battery age, and varying load.
Runtime hours = capacity (mAh) ÷ current draw (mA)
Worked example
A 3,000 mAh battery at a 500 mA average draw has an ideal runtime of 6 hours.
How to use this tool
- Enter the known values and choose units where available.
- Check the primary result and supporting details.
- Clear or replace an input to calculate another case.
Frequently asked questions
What happens with invalid or incomplete inputs?
The result remains blank until the required inputs form a finite, meaningful calculation. Zero denominators and physically impossible negative quantities are not calculated.
Can I use decimal values?
Yes. The tool accepts decimals and keeps full precision for the calculation while rounding the displayed result for readability.