Free Online Battery Life Calculator for Runtime Estimates
Estimate how long your battery will last under a specific load.
About This Tool
This free online battery life calculator helps you estimate how long a battery can power a device based on battery capacity, load current, and efficiency. It is useful for electronics projects, portable devices, IoT hardware, and runtime planning before you build or deploy something.
Because real-world systems lose energy through regulators, battery age, and operating conditions, the efficiency factor gives you a more practical estimate than a simple theoretical calculation.
If you are looking for a battery runtime calculator, battery backup estimator, or mAh to hours calculator, this tool gives you a fast browser-based way to compare different loads and battery sizes. It is helpful for students, makers, field technicians, and anyone designing low-power devices, battery-powered sensors, portable lights, or embedded systems.
Instead of estimating battery life manually with rough assumptions, you can use this calculator to test multiple scenarios in seconds. That makes it easier to compare capacities, understand how current draw affects runtime, and plan for more realistic usage before buying parts or finalizing a design.
Benefits and Use Cases
- Estimate battery runtime for electronics projects and portable devices
- Compare battery capacity against different current loads
- Plan runtime for IoT sensors, Arduino builds, and DIY hardware
- Check how efficiency losses affect real-world battery performance
- Make faster decisions when sizing batteries for backup or field use
How to Use
- Enter battery capacity and choose mAh or Ah.
- Enter the device load current and choose mA or A.
- Adjust the efficiency factor if needed.
- Click
Calculateto estimate runtime.
Frequently Asked Questions
What does this battery life calculator estimate?
It estimates how long a battery can power a device under a specific load.
Why is there an efficiency factor?
It accounts for real-world losses and makes the estimate more realistic.
Can I use mAh and Ah?
Yes. The tool supports both units.
Is this battery life calculator useful for Arduino or IoT projects?
Yes. It is useful for estimating runtime for microcontrollers, sensors, and other low-power electronics.