Strength 1RM Calculator & Training Program — 6 Formulas + Wendler 5/3/1 / Madcow 5×5 / Sheiko

Real-world use cases

• Set your first real training max after a 5RM PR

  You hit 140 kg × 5 on back squat last Saturday — your first rep PR in months. Plug it in. Median 1RM lands at ~163 kg across the six formulas (Epley calls it 163.3, Brzycki 157.5, Mayhew ~163, the rest in between). Pick Wendler 5/3/1; the tool builds a 4-week cycle off a 147 kg training max (90% × 163). Week 1 top set comes out at 125 kg × 5+, week 3 tops at 140 kg × 1+ — note that 140 is exactly your old PR, and you're meant to AMRAP it. If you grind 4 reps you've already passed your old max. That's the whole point of working off a training max.

• Pick today's plate weight from a stale 1RM number

  Your last 1RM test was 8 weeks ago: bench 110 kg. Today's program says "85% × 5". The %1RM table reads 93.5 kg → round to 92.5 kg (nearest 2.5 kg plate). Walk it out, do the first two reps — if the bar speed says RPE 7, the 1RM has gone up since the test and you can chase a top-set PR; if it feels RPE 9.5, drop to 87.5 kg and finish the work at the right RPE. The point isn't to lift exactly 92.5 today, it's to land at the RPE the program wanted.

• Compare Wendler vs Madcow vs Sheiko for your goal

  Same 1RM input (170 kg deadlift). Flip between the three programs. Wendler week 3 has one set: 161.5 × 1+. Madcow week 3 has five working sets ending at 153 × 5. Sheiko week 3 has six working sets ending at three sets of 144.5 × 2. Same lifter, same max — wildly different weekly volume. If you've got 25 hours a week of life and 4 hours of gym, Wendler. If you're an intermediate with strict recovery, Madcow. If you're peaking for a meet 12 weeks out and your sleep, food and stress are all dialled in, Sheiko.

• Translate a US lb-based program to kg without a calculator

  A US powerlifting program says "315 × 3 then 295 × 5 × 3" (lb). Flip the unit to lb, enter 315 × 3 → 1RM ~ 343 lb. Switch to kg, your 1RM reads ~156 kg automatically. Now the tool's %1RM table reads the kg plate weights for every percentage — 295 lb / 315 lb = 93.7%, table row 93% gives you 145 kg as the kg-bar equivalent of the prescribed 295 × 5 × 3. You're loading the right intensity even though the program was written for a 45 lb bar gym.

• Run a 4-week 5/3/1 cycle when 1RM data is older than the cycle

  You ran an 8-week mass block and lost track of where your 1RM is now. Test a 5RM on each lift in week 0 (warm-up, single all-out 5-rep set, write it down). Plug each in here → median 1RM → 90% training max → run a Wendler cycle. By the end of week 3 the AMRAP top set will have given you 1 to 3 extra reps on each lift, which Wendler uses to estimate a new 1RM (his rule: top weight × reps × 0.0333 + top weight). That number becomes the input for next cycle. No "real" 1RM testing needed.

Common pitfalls

• Plugging in a set where you stopped 3+ reps short of failure. Every formula assumes the last rep was true failure or within 1 rep of it. A "comfortable" 100 kg × 5 with 3 reps left is actually a ~115 kg × 5 if pushed; the calculator reads 117 kg as your 1RM, but reality is closer to 135 kg. Either go to RPE 9 on the input set, or use the result as a soft floor not an estimate.

• Treating a 10+ rep estimate as a real training-max number. Past 8 reps, fatigue, form breakdown and breathing dominate the equation; the 6 formulas start disagreeing with each other by 10%+. Use 1–6 reps for an honest training max, treat anything from 7–15 as ballpark, and never project from a 15+ rep set.

• Running the Wendler program off raw 1RM instead of 90% training max. This is the single most common error in 5/3/1 — lifters see the prescribed weights look "too light", crank up the inputs, and stall in 6 weeks because the AMRAP top sets become physically impossible. The training-max convention exists for a reason; respect it for one full 4-week cycle before judging.

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