FitCalculation

One Rep Max Calculator

Estimate your one-rep max from a submaximal set using five published formulas.

Your one rep max (1RM) is the heaviest weight you could lift for a single repetition with good form. Find out what your 1RM is without risking a max attempt: enter the weight you lifted and how many reps you completed, and this calculator estimates your 1RM for the bench press, squat, deadlift or any other lift using five common formulas. Your numbers stay in your browser.

Your set

Estimates only. Results vary by person and exercise and are most reliable for sets of 10 reps or fewer. Warm up properly and use a spotter or safety bars when training near your limit. Not medical advice.

What this calculates

Each formula extrapolates a one-rep max from the weight you lifted and the number of reps you completed, using a different mathematical model for how reps decline towards the maximum.

Method: Epley, Brzycki, Lombardi, Mayhew, O'Conner — five estimates from the same sub-maximal set. Accuracy: Estimates agree more closely at lower reps and diverge as reps increase. None should be treated as a measurement.

How to calculate your one rep max (formulas)

A one-rep max is estimated from the weight you lifted and the reps you completed. With w = weight lifted and r = reps completed, the five formulas this calculator uses are:

  • Epley1RM = w × (1 + r ÷ 30)
  • Brzycki1RM = w ÷ (1.0278 − 0.0278 × r)
  • Lombardi1RM = w × r^0.10
  • Mayhew1RM = (100 × w) ÷ (52.2 + 41.9 × e^(−0.055 × r))
  • O'Conner1RM = w × (1 + 0.025 × r)

The calculator works in kilograms and shows each formula's estimate alongside the median (the middle value across all five). For sets of 10 reps or fewer the formulas cluster closely; above that they diverge and the result is flagged as unreliable.

1RM for bench press, squat and deadlift

The same formulas apply to every lift, but the result is only as good as the set you enter. Use the exact exercise you want the 1RM for, with the same form and range of motion you'd use for a max attempt.

Bench press, 80 kg for 6 reps

Epley96.0 kg
Brzycki92.9 kg
Lombardi95.7 kg
Mayhew97.2 kg
O'Conner92.0 kg
Rangeroughly 92 to 97.2 kg

Squat, 140 kg for 5 reps

Epley163.3 kg
Brzycki157.5 kg
Lombardi164.5 kg
Mayhew166.6 kg
O'Conner157.5 kg
Rangeroughly 157.5 to 166.6 kg

Deadlift, 180 kg for 3 reps

Epley198.0 kg
Brzycki190.6 kg
Lombardi200.9 kg
Mayhew205.2 kg
O'Conner193.5 kg
Rangeroughly 190.6 to 205.2 kg

Research comparing prediction equations has found that different formulas fit different lifts best, and accuracy varies from person to person. Use the range rather than a single number, and re-estimate as you get stronger. The same approach works for other lifts such as the leg press and overhead press, though estimates for machine lifts can be less consistent.

Which one rep max formula is most accurate?

No formula wins for everyone. Epley and Brzycki are the most widely used and agree closely for most rep ranges, with Epley slightly generous and Brzycki slightly conservative. Lombardi is the most optimistic at higher reps, Mayhew is fitted to bench-press data, and O'Conner is the most conservative.

Accuracy is best at lower rep counts, roughly 10 or fewer, because the relationship between reps and max is more consistent there. It drops as reps rise and the set moves further from a true max. Results also vary by exercise and by person, which is why this page shows a range rather than one exact number.

Using your 1RM to choose training weights

Coaches commonly prescribe training loads as a percentage of your estimated 1RM. The table below is an approximate guide:

Percentage of 1RMApprox. reps you can do
95%about 2
90%about 4
85%about 6
80%about 8
75%about 10
70%about 12

Real numbers vary by person and exercise. Treat these as starting points and adjust to how your sets feel.

For a full walkthrough of reading the five estimates and turning them into working loads for your program, see the guide on using your one-rep max.

Is it safe to test your true one rep max?

Estimating from a lighter set taken to or near failure is generally safer than attempting a true max, because you are never maxing out. If you do test a true max, warm up progressively, use a spotter or safety bars, and avoid it if you are new to the lift or have an injury. Stop the moment your form breaks down.

These formulas are estimates, not safe-testing instructions, and this is general information, not medical advice.

Frequently asked questions

What is my one rep max?
Your one rep max (1RM) is the heaviest weight you can lift for a single repetition with good form. Enter the weight you lifted and the number of reps you completed in the calculator above, and it estimates your 1RM using five formulas, plus the range between them. Each exercise has its own 1RM, so your bench press, squat and deadlift numbers will all differ.
How do I calculate my one rep max?
Lift a weight for as many reps as you can with good form, then use a formula. The Epley formula is weight × (1 + reps ÷ 30). For example, 100 kg for 5 reps gives 100 × (1 + 5 ÷ 30) = 116.7 kg. The calculator above runs five formulas at once and shows the range.
How do I calculate my bench press, squat or deadlift 1RM?
Use the same calculator and enter a set from that exact lift. For example, 80 kg for 6 reps on the bench press gives an estimated 1RM of roughly 92 to 97.2 kg, and 140 kg for 5 reps on the squat gives roughly 157.5 to 166.6 kg. The formulas are the same for every lift, so the quality of the estimate depends on a set done with good form and a consistent range of motion.
Which 1RM formula is most accurate?
There is no single best one. Epley and Brzycki are the most widely used, but accuracy varies by person and by exercise. All of them are most reliable at lower rep counts, roughly 10 or fewer. That's why this calculator shows several formulas and a range, rather than one exact number.
How many reps should I use to estimate my 1RM?
Sets of about 3 to 8 reps tend to give the most reliable estimates, and anything above about 10 reps gets noticeably less accurate. Do the set with good form, stop at or just before failure, and use the same exercise you want the 1RM for. Treat the result as a starting point and adjust based on how your training actually feels.
How do I use my 1RM to choose training weights, for example for 5x5?
Multiply your 1RM by a percentage. As a rough guide, about 80% of your 1RM is a weight you can lift for around 8 reps, and about 70% for around 12. Many 5x5 programs start somewhere around 80 to 85% of your 1RM, but these are approximations that vary by person, exercise and program, so adjust to how the sets feel. For example, with a 1RM of 100 kg, 80% is 80 kg.
Does this work for leg press, overhead press and other lifts?
Yes, you can enter a set from any lift. The estimates tend to be less consistent for machine lifts such as the leg press, because machines differ in range of motion and loading, so treat those results as rougher guides. Always use the same machine and setup when comparing over time.
Is it safe to test my true one rep max?
It carries more risk than lighter sets, especially if you are new to the lift, fatigued or training alone. Estimating from a heavy set of several reps is generally safer. If you do test a true max, warm up progressively, use a spotter or safety bars, and stop if your form breaks down. This is general information, not medical advice.

Sources and last reviewed

Last reviewed: October 2026

  1. Epley SM. (1985), The Poundage Chart: a new approach to the one-repetition maximum, Strength and Conditioning 7(4):38-39
  2. Brzycki J. (1993), Strength Testing—Predicting a One-Rep Max from Reps-to-Fatigue, Journal of Physical Education, Recreation and Dance 64(2):124-129
  3. Lombardi WL. (1989), Single vs. multiple-repetition strength testing to determine 1RM, Beginning Weight Training, Wm. C. Brown
  4. Mayhew JE, Uchima D, Ware JS, et al. (1992), Prediction of multiple-repetition bench press maximum in college men, Journal of Strength and Conditioning Research 6(3):122-127
  5. O'Conner H. (1989), Predicting 1RM from submaximal loads, Weight Training Today 4(8):60-63
  6. LeSuer DA et al. (1997), The accuracy of prediction equations for estimating 1-RM performance in the bench press, squat, and deadlift, Journal of Strength and Conditioning Research 11(4):211-213