Free Battery Life Calculator Online
Calculate device battery life from capacity (mAh), current draw (mA), and efficiency factor. Estimate charging time from voltage and amperage ratings. — 100% free online utility, zero sign-up, zero paywalls, and private client-side processing.
How It Works
Enter Battery Capacity
Input battery capacity in mAh or Wh.
Enter Current Draw
Input device's average current consumption in mA.
Set Efficiency Factor
Apply 70-90% efficiency factor for real-world conditions.
View Battery Life
See estimated battery hours and charging time from charger specs.
Frequently Asked Questions
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