OneTool

Battery C-Rating Calculator

I_max ≈ C × capacity (Ah) — and the reverse check.

Mode

Capacity

2.2 Ah

mAh / 1000

Max continuous current

44 A

Imax = C × capacity_Ah

Manufacturer C-ratings vary; continuous discharge may be lower than burst ratings. Size packs with margin for heat and voltage sag.

What is this tool?

C-rating describes allowable discharge relative to capacity: a 1000 mAh (1 Ah) pack at 20C is often marketed for about 20 A continuous (manufacturer definitions vary). Burst ratings and thermal limits differ — verify the datasheet.

How to use it

  1. Enter capacity and C-rating to get max continuous current, or enter a load current to see required C.
  2. Compare against your expected current draw with margin.
  3. Confirm continuous vs burst specs on the pack label/datasheet.