# Battery Energy Calculator

> Calculate battery energy step by step: Pack V = cell V × series count; pack Ah = cell Ah × parallel count; Energy (Wh) = pack V × pack Ah.

Page: https://freecalculator.tech/tools/battery-energy-calculator
Last reviewed: 2026-11-03

## Formula

Pack V = cell V × series count; pack Ah = cell Ah × parallel count; Energy (Wh) = pack V × pack Ah.

- Series adds voltage, parallel adds capacity; energy is the product.
- Cell counts must be positive whole numbers.
- Uses nominal voltage, which is the usual basis for rated energy.
- Pack V = cell V × series count; pack Ah = cell Ah × parallel count; Energy (Wh) = pack V × pack Ah.
- Inputs used: Capacity per cell or battery, Nominal voltage, Cells in series, Strings in parallel.

## Inputs

- Capacity per cell or battery
- Nominal voltage
- Cells in series
- Strings in parallel

## Worked example: 4S2P pack of 3.6 V 3 Ah cells

Energy of a small lithium-ion pack.
1. Voltage: 3.6 × 4 = 14.4 V.
2. Capacity: 3 × 2 = 6 Ah.
3. Energy: 14.4 × 6 = 86.4 Wh.

## Common questions

### Why do airlines ask for watt-hours?

Watt-hours measure stored energy regardless of voltage, so they are used for battery transport limits. Check your airline's current rule.

### Is mAh the same as Wh?

No. mAh ignores voltage. Divide mAh by 1,000 to get Ah, then multiply by voltage to get Wh.

### Is all this energy usable?

No. Depth of discharge limits and conversion losses reduce usable energy; the battery runtime calculator accounts for both.

### How do I use the Battery Energy Calculator?

Enter the required values for Capacity per cell or battery, Nominal voltage, Cells in series, Strings in parallel. The calculator applies the formula on this page and shows the main result with any supporting breakdown so you can check the arithmetic.

### What formula does the Battery Energy Calculator use?

Pack V = cell V × series count; pack Ah = cell Ah × parallel count; Energy (Wh) = pack V × pack Ah. The visible formula section above lists the calculation path and the edge cases the page handles, so the result can be checked without relying on the form alone.

### Can the Battery Energy Calculator be used for exact decisions?

Use it as a calculation aid, not as a substitute for checking the underlying rule, contract, policy, or professional advice that applies to your situation. When a result depends on local rules, personal details, prices, or dates, enter those values yourself and confirm them before acting.

## Limitations and assumptions

- Nominal rating only; actual energy varies with rate and temperature.
- Assumes identical, balanced cells.
- Ageing is ignored.
- Results are estimates for planning and learning. Real designs, installations and bids must be checked by a qualified, licensed professional against the codes that apply where you work.
- The result depends on the values you enter for this battery energy calculator; it does not supply missing rates, rules, prices, dates, or assumptions for you.

## Sources

- OpenStax (Rice University) — https://openstax.org/details/books/university-physics-volume-2

## Cite this page

- APA: Free Calculator. (2026, November 3). Battery Energy Calculator. https://freecalculator.tech/tools/battery-energy-calculator
- MLA: "Battery Energy Calculator." Free Calculator, 3 Nov. 2026, https://freecalculator.tech/tools/battery-energy-calculator.
- Link: Battery Energy Calculator — Free Calculator, https://freecalculator.tech/tools/battery-energy-calculator