Want to know how long your device’s battery will last? Use this simple calculator to estimate battery life based on capacity, power usage, and efficiency. Whether it’s for a phone, laptop, or gadget, this tool helps you figure out how much time you can expect before the next charge.

How to Calculate Battery Life

Battery life depends on a few key factors:

• Battery Capacity (mAh or Wh): The total amount of energy the battery can store.
• Device Power Consumption (W or mA): How much energy your device uses while running.
• Efficiency: Not all energy is used perfectly—heat and other losses reduce actual usage time.

The general formula is:

Battery Life = Battery Capacity ÷ Device Power Consumption

For example, if you have a 4000 mAh smartphone battery and your phone uses 400 mA per hour, you’ll get about 10 hours of use before needing a recharge.

Why Battery Life Matters

Knowing battery life helps you:

• Plan usage for travel or work.
• Compare devices more accurately.
• Avoid running out of power at the worst time.

Whether you’re checking your phone, laptop, or any rechargeable device, our calculator gives you a quick and reliable estimate.