To calculate how long a battery will last, divide the battery capacity in amp-hours by the current in amps.
The Ah to Hours Calculator helps you determine how long a battery will last when you know its capacity in amp-hours (Ah) and the current being drawn in amps (I). This calculation is important when estimating battery life for appliances, devices, or systems that rely on stored energy.
It helps in planning energy use efficiently, especially for systems like solar setups or backup power sources. Using this simple formula, you can predict how long a battery will power a device before it needs to be recharged.

Formula
Contents
T = Ah / I
Variable | Description |
---|---|
T | Time (hours) |
Ah | Battery capacity in amp-hours |
I | Current drawn by the device in amps |
How to Calculate ?
- Determine the battery capacity in amp-hours (Ah).
- Find the current (I) being drawn by the device in amps.
- Use the formula: divide the battery capacity (Ah) by the current (I).
- The result will be the number of hours the battery will last.
Solved Calculations :
Example 1
Step | Calculation |
---|---|
Given Ah | 100 Ah |
Current (I) | 5 amps |
T Calculation | 100 Ah ÷ 5 amps |
Result | 20 hours |
Answer: The battery will last for 20 hours.
Example 2
Step | Calculation |
---|---|
Given Ah | 200 Ah |
Current (I) | 10 amps |
T Calculation | 200 Ah ÷ 10 amps |
Result | 20 hours |
Answer: The battery will last for 20 hours.
What is Ah to Hours Calculator ?
An Ah to hours calculator helps you determine how long a battery will last based on its capacity in amp-hours (Ah) and the load it’s powering.
For example, a 12V battery’s capacity can be converted into watt-hours using a simple conversion: Amp hours to watt hours (Wh). To find out how long a battery can run an appliance, you divide the total watt-hours by the power consumption of the device in watts.
For instance, 100 Ah to watts conversion can be calculated using a 12V battery, which would give you 1,200 watt-hours (100 Ah × 12V). If your device uses 100 watts, the battery would last approximately 12 hours. The same method applies to other values, such as 200 Ah to watt-hours or smaller devices that draw less power.
Final Words:
Understanding battery run time is essential for determining how long a device can function before needing a recharge. Whether using a battery amp hours chart or calculating manually, this method ensures accurate results.