Battery runtime calculator

How long a battery lasts — capacity × efficiency ÷ average load, with duty-cycle calendar time.

Numbers stay in this browser — nothing is sent anywhere.

Simple estimate: capacity × efficiency ÷ average load. Real devices rarely draw a steady current — peaks, standby sleep, and temperature change the answer. Duty cycle stretches the calendar time but not the active-run hours.

How to use

  1. Enter the capacity (mAh or Ah) and average draw (mA or A).
  2. Set efficiency and duty cycle.
  3. Read active run time and calendar run time.

What it supports

Simple estimate: capacity × efficiency ÷ average load. Real devices rarely draw a steady current — peaks, standby sleep, and temperature change the answer. Duty stretches calendar time, not active hours.

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