# Battery Life Calculator

> Battery life calculator: estimate device runtime from battery capacity in mAh or Wh and current draw. Editable efficiency losses, free, runs locally offline.

- **Canonical URL:** https://boringtoolskit.com/battery-life-calculator/
- **Category:** Energy & Electrical
- **Evidence level:** catalogue
- **Reviewed:** July 26, 2026
- **Last verified:** 2026-10-12
- **Privacy:** Inputs and results stay in this browser unless the page clearly labels an external request.

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