C rating is a multiplier used to express a battery’s stated discharge current relative to its capacity. It is commonly shown on LiPo batteries as values such as 30C, 50C, or 100C.

The label-based current can be calculated with this formula:

Current (A) = Capacity (Ah) × C Rating

For example, a 1500mAh battery has a capacity of 1.5Ah. If it is labeled 30C, the calculation is:

1.5Ah × 30C = 45A

This means the manufacturer states that the battery can provide 45 amps under the rating’s specified conditions. It should not be treated as a guarantee of identical real-world performance across different brands or testing methods.

For drone users, the battery’s discharge capability should be matched to the aircraft’s verified current demand. Motor and propeller test data, ESC limits, wiring, connectors, temperature, battery age, internal resistance, and cooling can all affect actual performance.

Continuous and burst C ratings are different. A continuous rating applies to sustained discharge, while a burst rating applies only for the duration and conditions specified by the manufacturer. Use continuous ratings when planning for sustained loads.

Printed C ratings are not always directly comparable between manufacturers. When possible, also consider manufacturer test data, internal resistance, voltage sag, operating temperature, and independent load testing.