Should You Add Reps or Weight: The Calculator

Assumptions and background

You're training to failure and doing a double progression. This won't make much sense if you're doing single progressions or standard 3 $\times$ 12 with a bunch of Reps in Reserve.

The calculator is an experiment in progressive overload measured in single percentage points. The goal is to "beat the logbook" using reasonable incremental improvements. If you follow the calculator, that will sometimes mean lowering the weight and adding extra reps or sometimes making large jumps in weight and doing far fewer reps.

I have no idea if this is a valid way to train. It's here to scratch an itch.