How heavy your drone can be depends on how you want to operate it.
Your drone can weigh up to 25kgs and must always be safe to operate.
However, if your drone weighs between 15-25kgs it must be inspected by an approved organisaton to check that it is airworthy first.
The following organisations or persons have been approved by the Director to do this:
If you want to fly a drone over 25 kgs, or fly outside of the part 101 rules, you must apply for a part 102 unmanned aircraft operator certificate before you fly.