How to Calculate Your One-Rep Max

Your one-rep max (1RM) is the heaviest weight you can lift for a single clean repetition. It's the number every strength program is built on: percentages of your 1RM decide your working weights, track your progress, and tell you when to add plates. The good news? You don't need to grind out a risky true max to know it — you can calculate a reliable estimate from any hard set of 3–6 reps.

Method 1: The Epley Formula

The most famous 1RM formula is dead simple:

1RM = weight × (1 + reps ÷ 30)

Example: you bench 100 kg for 5 reps. 100 × (1 + 5/30) = 116.7 kg. That's your estimated max, and it's usually within a few percent for sets under 10 reps.

Method 2: The Brzycki Formula

1RM = weight × 36 ÷ (37 − reps)

The same 100 kg × 5 set gives 100 × 36/32 = 112.5 kg. Brzycki tends to run slightly more conservative than Epley at higher rep counts. When both formulas agree closely — as they do here — you can trust the average. Our one-rep max calculator shows both side by side so you can compare.

Which Set Should I Test?

For the best estimate:

Use a set of **3–6 reps** to true technical failure (or 1 rep in reserve)

Warm up properly — 5+ progressive sets before the test set

Re-test under similar conditions (sleep, food, time of day)

Sets above 10 reps skew the math badly, because muscular endurance — not max strength — becomes the limiting factor.

Turning 1RM Into a Training Plan

This is where the number becomes useful. Standard percentage benchmarks:

**90–95%**: singles and doubles, peak strength

**80–87%**: 3–5 rep strength work (the bread and butter of 5×5 programs)

**70–75%**: hypertrophy and volume work

**50–65%**: speed work and technique

Our 1RM percentage chart generates the full table from your max in one click.

Beyond the Big Three

Once you know your maxes, you can go further: check whether your lifts are balanced with the bench-squat-deadlift ratio calculator, compare totals across bodyweights with Wilks and DOTS scores, or stop doing plate math with the barbell plate calculator.

Conclusion

Calculating your 1RM from a 5-rep set takes 30 seconds and removes the guesswork — and the risk — from max testing. Enter your best recent set into the one-rep max calculator and start programming your next block with real numbers.