Battery Life Calculator
Estimate how long a battery will power your device using battery capacity, voltage, device consumption, efficiency, and usable battery percentage.
Enter battery and device details
Result
Enter your values and calculate the estimated runtime.
Battery capacity
Capacity may be entered in milliamp-hours, amp-hours, or watt-hours. Voltage converts charge capacity into stored energy.
Real-world efficiency
Converters, regulators, heat, and wiring losses reduce usable energy. A value between 80% and 95% is common.
Usable capacity
Leaving a reserve protects many batteries from deep discharge and can improve their long-term lifespan.
Frequently asked questions
How is battery life calculated?
The calculator converts the battery capacity to watt-hours, applies efficiency and usable-capacity limits, then divides by the device's wattage.
Why is actual runtime usually lower?
Battery age, temperature, peak loads, converter losses, and manufacturer ratings can all reduce real-world runtime.
Can I enter current instead of watts?
Yes. Select milliamps or amps for device consumption. The calculator uses the battery voltage to convert current into watts.
Does this work for power banks and solar batteries?
Yes, as long as you know the rated battery capacity, voltage, and approximate device consumption.
Results are estimates generated locally in your browser using standard electrical formulas. They are for informational and planning purposes only, not a substitute for a qualified electrician. Confirm all wiring, load and safety requirements against your local electrical code before installation. VisionVix accepts no liability for decisions based on this tool's output.
