C-rating indicates how quickly a battery can safely discharge its capacity. A higher C-rating means faster possible discharge rates. The formula is:
Maximum Current Draw = Capacity (in Ah) × C-rating
For example, a 2000mAh (2Ah) battery with a 20C rating can safely deliver up to 40A (2 × 20). Most drone batteries range from 15C to 100C. Racing drones typically need higher C-ratings (50C+) for rapid acceleration, while photography drones can use lower ratings (15-30C). Always choose a C-rating that exceeds your drone's maximum current draw to ensure safe operation.