C-Rate Calculator

Light Mode

Enter discharge current, cell capacity, and optional discharge time. Outputs include C-rate and estimated discharge time.

Discharge Current (A)

The current drawn from the cell in real-time. Example: a motor pulling 10A from the cell.

Cell Capacity

Nominal cell capacity. Enter value in Ah or mAh depending on the unit.

Capacity Unit

Select if you entered capacity in mAh or Ah. The tool converts automatically.

Discharge Time (optional — compare)

If you know how long the discharge takes, enter it here to calculate C-rate from time and compare.

Time Unit

Number of Series Cells

Number of cells connected in series.

Number of Parallel Cells

Number of cells connected in parallel.

Pack Safety Factor (optional)

Safety margin multiplier to prevent overloading (default 1.0).

Result:

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Quick explanation: C-rate = Current (A) ÷ Capacity (Ah). Example: 2.5A discharge on a 2.5Ah cell = 1C (full discharge in ~1 hour).