Add weight once you hit the top of your rep range on all sets with 1 to 2 reps still in reserve.
Increase the weight when you complete the top of your target rep range across all your working sets with clean form and a rep or two still in the tank. If your range is 8 to 12 and you get 12 on every set, add 2.5 kg on compounds or the smallest jump on isolation next session. If reps then drop into the low end, that is expected, work back up and repeat.
Pick a rep range, add reps within it week to week, and once you top the range on every set, bump the load. This double progression keeps you always either adding reps or adding weight, which is progressive overload in practice.
Big compounds like squats and deadlifts can take 2.5 to 5 kg jumps; presses and isolation often need micro plates of 1 to 2 kg so you do not stall. Smaller muscles tolerate smaller increases.
After adding weight your reps will drop toward the bottom of the range, and that is correct. Grind those reps back up over the next sessions, then increase again. A app that suggests your next weight from logged sets removes the guesswork.
Add weight once you hit the top of your rep range on all sets with 1 to 2 reps still in reserve.
