Battery Life Calculator
A useful tool for electronics hobbyists and engineers. Estimate how long a battery will last based on its capacity and the average current draw of your device.
How Long Will It Last?
One of the most common questions in electronics projects is "How long will my battery last?". The answer depends on two main things: how much energy the battery can store (its capacity) and how quickly the device uses that energy (its consumption).
The Formula and a Dose of Reality
The basic formula is simple: `Battery Life (in hours) = Battery Capacity (in mAh) / Device Consumption (in mA)`. However, this gives a perfect-world scenario. In reality, a battery's stated capacity is rarely fully usable.
- Aging: All batteries lose capacity over time.
- Temperature: Extreme cold or heat can significantly reduce performance.
- Discharge Rate: Drawing current very quickly can be less efficient and reduce the usable capacity.
To provide a more realistic estimate, this calculator applies a **70% de-rating factor** to the battery's capacity. This means it assumes you can only use 70% of the stated capacity, which is a common and safe practice for estimation.