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Battery Life Calculator
Runtime from capacity (mAh) and current draw.
10 h 12 min
Runtime
10.2
Hours
0.43
Days
Runs entirely in your browser. Nothing is sent anywhere.
How it works
- 1Enter your values.
- 2See the result update instantly as you type.
- 3Change any value to compare scenarios.
About this tool
Battery Life Calculator: Runtime from capacity (mAh) and current draw. Type your numbers and the result is calculated instantly — no button to press, nothing to install. All math runs locally in your browser, so the values you enter are never sent anywhere.
Example
| Input | |
|---|---|
| Capacity (mAh) | 3,000 |
| Current draw (mA) | 250 |
| Usable capacity (%) | 85 |
| Result | |
| Runtime | 10 h 12 min |
| Hours | 10.2 |
| Days | 0.43 |
How do I use the Battery Life Calculator?
Enter your values. See the result update instantly as you type. Change any value to compare scenarios.
Is the Battery Life Calculator free?
Yes. It is completely free with no sign-up, no usage limits and no watermark.
Is my data sent to a server?
No. Everything is calculated locally in your browser. Nothing you enter is uploaded, logged or stored.
Does it work on my phone?
Yes. It works in any modern browser on Android, iPhone, iPad, Windows, Mac and Linux — no app needed.