What is 5/3/1, and why does it work?

Jim Wendler's 5/3/1 is the most durable strength program in modern training. Built around the four big barbell lifts — squat, bench, deadlift, and overhead press — it runs in four-week cycles, with each week targeting a different intensity zone. The genius isn't in the percentages. The genius is in three principles:

Train off a submaximal Training Max, not your true 1RM.

Wendler's original recommendation was 90% of your true 1RM as the Training Max (TM) that all percentages calculate from. The 10% buffer protects form on bad days, keeps cumulative joint stress manageable, and leaves room to push the AMRAP set. In his more recent writing, Wendler himself has moved toward 80–85% as a starting point — this calculator defaults to 85%, with the full 80–95% range available depending on training experience and goals.

The AMRAP set is the engine.

On the final working set of weeks 1, 2, and 3, you push for as many quality reps as possible. That single set does three jobs at once: it's an honest test of where you are today, it's the autoregulation mechanism that tells you whether to increase or hold your TM next cycle, and it's where most of the strength adaptation actually happens. If you can only do the prescribed minimum, hold your TM. If you blow past it, push the TM up. The calculator handles all of that math for you.

Slow progress beats fast plateau.

Wendler's increments are small on purpose. +2.5 kg on upper body lifts, +5 kg on lower body lifts per cycle. Over a year of consistent training, that's 30 kg upper / 60 kg lower — far more than most lifters add chasing weekly PRs and burning out by month three.

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The six sessions in this calculator