Welcome! This battery size calculator will allow you to determine an appropriate battery size in Amp-hours given load, supplied voltage, duration, battery type and charge.
Choosing the most appropriate battery for a circuit is a critical choice in designing a selected circuit. The type of battery also plays a crucial part in implementing this.


⬇️ Inputs




⬆️ Outputs

B (Lith)

B (Lead)

⛔️ No Load Current Given...

If the supplied load doesn't give a rated amperage, you can use the following calculation to manually determine the load current:


Rated power (W)

Rated voltage (V)

Rated current (A)

💬 We'd love your feedback on this template! It takes 1min


The most important specification of a battery is its current rating. The rated capacity of any battery expresses the average amount of current it releases over a period of time under normal use. For example, a 4000Ah battery can deliver 100 A for 40 hours.
The type of battery selected also plays an important role in battery size. Lead-acid batteries have a battery rating proportional to their discharge rate.

For lithium-ion batteries:

For lead-acid batteries:


Additional Resources

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