One-rep max

Before you rely on it

What to check

Base the estimate on a set taken genuinely close to failure at a moderate rep count.

The common error

Where people go wrong with one-rep max

Estimating from a high-rep set. The formulas drift badly past about ten reps, and they drift upward. So the number comes out flattering and the programme comes out unmanageable.

Worked through

One-rep max in plain numbers

Lift 100 kg for five clean repetitions. The Epley formula estimates a one-repetition maximum of 100 × (1 + 5 ÷ 30), which is about 116.7 kg; the Brzycki formula gives 100 × 36 ÷ (37 − 5), or 112.5 kg. Two respected formulas, a gap of four kilograms. Most trainers work with the range, and use the estimate to set training percentages: 80% of 115 kg is 92 kg. Estimating from sets of three to ten repetitions is generally more reliable than from very high repetitions; it also spares the risk of attempting a true single at the limit.

Easily confused

One-rep max and its neighbours

The one-rep max is a measured or estimated maximum for a single repetition; it is not the same as training max, which is a conservative figure some programs use to plan loads. It differs from a rep max at other counts, such as a five-rep max, and from a strength standard for body weight. Different formulas give different estimates, and none is exact. Estimated 1RM is not a promise about what you can lift on a given day, since fatigue, sleep and technique affect performance.

In real decisions

Where one-rep max turns up

Lifters and coaches use estimated one-rep maxes to set percentages for programs, to track progress and to compare across lifts. Powerlifting programs are often built on percentages. Calculators let you enter the weight and repetitions from a recent set. Progress can be tracked without repeatedly testing a true maximum; comparing estimates over months shows whether training is working.

Know the edges

Where one-rep max stops being reliable

Formulas are approximate and vary by lift, experience and rep range. Testing a true one-rep max carries injury risk and should be done with proper warm-up, technique and spotters. This page is educational and not medical or training advice, and people with health conditions or injuries should consult a professional before heavy lifting.

Quick answers

What people ask about one-rep max

Which formula is most accurate? None is exact. Epley and Brzycki are common, and they agree closely for sets of about three to eight repetitions. Accuracy drops for high repetitions.

Should I test a true one-rep max? Only with good technique, warm-up and spotters, and if it suits your training. Estimating from a submaximal set is safer for most lifters.

How do I use it to set weights? Take a percentage of the estimate. For example, work sets at 75 to 85 percent are common for strength training. Adjust to how you feel.

Does the estimate differ between lifts? Yes. Formulas fit some lifts better than others, and technique and fatigue matter. Use your own history to check the estimates.