Battery Life Calculator: mAh to Hours

Estimate how many hours a battery or power bank will run a device, and the energy it stores in watt-hours.

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How to use the battery life calculator

  1. Type your numbers in the boxes (pick your currency or units if asked).
  2. The answer updates as you type: no button to press.
  3. Copy the result, or share it on WhatsApp with one tap.

Questions

Is my data private?

Yes. Everything happens inside your own browser: nothing you type or choose is uploaded to us or anyone else.

Is it free?

Completely free, with no sign-up, no watermark and no limit on how many times you use it. Light ads keep the site running.