Battery Life Calculator

In the realm of small, battery-powered devices such as clocks, microcontrollers, and gadgets powered by AA/AAA batteries, understanding how long a battery will last is essential. To assist with this, we have developed a versatile little calculator specifically tailored for these applications.

The Battery Life Calculator is a user-friendly tool designed to estimate the number of hours a small device can operate before its battery is depleted. By inputting two out of the three key variables—Battery Capacity, Device Consumption, and Estimated Hours—the calculator will automatically compute the third variable. This tool is invaluable for hobbyists, engineers, and anyone working with small, battery-powered devices.

How does it work?

The calculator operates based on a simple formula derived from the principles of electrical engineering:

Estimated Hours = Battery Capacity / Device Consumption

Here's a quick breakdown of the components:

  • Battery Capacity: This is the total charge a battery can hold, usually measured in Ampere-hours (Ah) or milliampere-hours (mAh). A higher capacity means the battery can provide power for a longer period.
  • Device Consumption: This is the rate at which the device uses power, measured in Amperes (A) or milliamperes (mA). Lower consumption indicates the device uses less power, thereby prolonging battery life.
  • Estimated Hours: This is the total number of hours the device can run before the battery is empty, calculated based on the battery capacity and device consumption.

Example usage scenarios

  • Scenario 1: You have a clock with a battery capacity of 2000 mAh and it consumes 10 mA. Enter these values into the calculator, and it will estimate that the clock will last for 200 hours. (Estimated Hours = 2000 mAh / 10 mA = 20 hours)

  • Scenario 2: You need a microcontroller to run for 50 hours and know that it consumes 20 mA. Enter these values, and the calculator will tell you that you need a battery with a capacity of 1000 mAh. (Battery Capacity = 50 hours * 20 mA = 1000 mAh)

  • Scenario 3: You have a 3000 mAh battery and need it to last for 60 hours in a small device. The calculator will inform you that your device should not consume more than 50 mA. (Device Consumption = 3000 mAh / 60 hours = 50 mAh)

Benefits of Using the Battery Life Calculator

  1. Convenience: Quickly estimate battery life without complex calculations.
  2. Planning: Helps in planning for recharges or battery replacements.
  3. Optimization: Assists in selecting devices or components that align with your battery life requirements.
  4. Educational: Enhances understanding of battery dynamics and power consumption.

Additional Tips

  • Understand Your Device: Different devices have varying power needs. Check the manufacturer's specifications for accurate consumption rates.
  • Battery Health: Keep in mind that battery capacity can degrade over time, affecting the estimated hours.
  • Usage Patterns: Real-life usage can vary due to factors like duty cycle, operational mode, and environmental conditions. Use the calculator as a guide rather than an absolute measure.


The Battery Life Calculator is a tool designed to simplify the process of estimating how long a battery will last in small devices. By providing an intuitive interface and reliable calculations, it empowers users to make informed decisions about their battery usage. Whether you're a hobbyist, an engineer, or a casual user, this calculator is an essential resource for maximizing the efficiency and longevity of your battery-powered devices.

Embrace the power of knowledge with the Battery Life Calculator, and take control of your device's battery life today!