Auto-progression

Every exercise has a target rep range. The default is 10 to 15, and you can change it globally or for one exercise. When you finish a set, StackUp compares what you did to that range and marks the exercise with one of three outcomes.

Above the range and the weight goes up next time. Below it and the weight comes down. Inside it — including exactly on either end — and the weight stays where it is. The step is 2.5 kg by default, per exercise if you want something else, and the next session opens with the adjusted number already filled in.

When your sets carry different weights, the decision reads the heaviest working set. Press 60×12, 70×10 and 80×8 and the 8 decides, not the 12 — the top set is the one that says what you can actually lift. Straight sets, where every set is at the same weight, use the first set by default, and you can switch that to the last set, the best set or the average.

Sets you have marked as a warm-up are left out of this entirely — see warm-up sets. Cardio is left out too: it is logged, not judged.

One session below the range is enough: the weight comes down by one step the very next session. A deload is the exception to that. Go down three sessions in a row and a single step down clearly is not answering the problem, so the suggestion drops to 90 % of your last weight instead — the app noticing you are stuck rather than grinding you further into the ground. A skipped session does not count towards the streak.

For bodyweight exercises there is nothing to add, so progression moves the target reps instead of the weight, one rep at a time.

On your very first session an exercise has no history, so nothing is invented: you type the weight you are actually using, and the app takes over from the second session onward. Progression belongs to the exercise, not to the workout it sits in, so the same bench press in two different splits is one progression.