An important part of safe flying is knowing your Remotely Piloted Aircraft (RPA) well. Not just “how to fly it” without crashing, but about it.
Micro: <100 grams
Very Small: 101 grams to 2 kg
Small: 2.01 kilograms to 25 kg
Medium: 25.01 kg to 150 kg
Large: More than 150 kg
You must know the actual weight of your drone before a flight. Any changes to an RPA (a different lens, a new battery, a sticker!) could move you from one weight category to another – the commercial name of the RPA, the weight at purchase, what you “thought” it weighed. are all irrelevant. As the pilot, YOU are responsible for what you have in the air and for operating that equipment safely and legally.
You can find additional information, including links to the official technical definition for each RPA on the CASA website.