# Battery pack calculator: series, parallel, energy and C-rating current

> Calculate pack voltage, capacity, energy in Wh and maximum continuous current from cell count, series and parallel layout and C rating.

Canonical: https://roboticsengineering.in/battery-pack-series-parallel-calculator/ | Published: 2026-11-03 | Updated: 2026-11-03

**Series adds voltage, parallel adds capacity, and the C rating sets the current limit.** Enter the cell and the layout to get the pack figures.

Cells in series (S)Cells in parallel (P)Nominal cell voltage (V)Full cell voltage (V)Cell capacity (Ah)Continuous C rating

Nominal voltage: **–** V (full: – V)Capacity: **–** AhEnergy: **–** WhMax continuous current: **–** A

Use the continuous rating from the cell datasheet, not the peak. Keep margin, and use a proper battery management board.

## How it is calculated

Pack voltage = cells in series × cell voltage. Pack capacity = cells in parallel × cell capacity. Energy in Wh = nominal voltage × capacity. Maximum continuous current = capacity in Ah × C rating.

## A worked example

A 3S2P pack of 2.5 Ah cells at 3.7 V nominal gives 3 × 3.7 = 11.1 V nominal (12.6 V full), 2 × 2.5 = 5 Ah and 11.1 × 5 = 55.5 Wh. With a 10C rating the limit is 5 × 10 = 50 A.

## Common mistakes

- Treating the full-charge voltage as the working voltage.
- Using the peak C rating as the continuous one.
- Mixing old and new cells in one pack.

## Related

[battery runtime calculator](https://roboticsengineering.in/robot-battery-runtime-calculator/), [robot battery guide](https://roboticsengineering.in/robot-battery-guide/), [wheel speed calculator](https://roboticsengineering.in/wheel-speed-rpm-calculator/).

Last reviewed: November 2026. The calculator runs in your browser and sends nothing anywhere. Results are ideal-case figures; add margin before you order parts.