Free calculator
One Rep Max (1RM) Calculator
Written by the GymStreak coaching teamUpdated
Use a set you finished with good form, taken close to failure. Sets of 3–8 reps give the best estimates.
The short answer
Your one-rep max (1RM) is the heaviest weight you can lift once with good form. You can estimate it without maxing out: lift a weight for 3 to 8 hard reps, then use a formula such as Epley, 1RM = weight × (1 + reps ÷ 30). For example, 100 kg for 5 reps gives an estimated 1RM of about 114 kg.
01 / How it works
How the one rep max calculator works
The more reps you can do with a weight, the further that weight is below your maximum. Researchers have measured this relationship in many lifters and turned it into formulas. Give the calculator the weight and the number of reps from one hard set, and it works backwards to the single-rep maximum.
It runs three well-known formulas, Epley, Brzycki and Lander, and shows the average as your estimate. They agree closely for sets of up to about 10 reps and drift apart above that, which is why the calculator stops at 12. The set you enter should be taken close to failure: if you could have done three more reps, the estimate will be too low.
Below the result you get a training table: the load for each percentage of your 1RM, rounded to the nearest 2.5 kg or 5 lb, and roughly how many reps most people can do at that load.
02 / Formula
The one-rep max formulas
Epley formula
1RM = w × (1 + r ÷ 30)
- w = weight lifted (kg or lb; the answer comes out in the same unit)
- r = reps completed
The most widely used formula. It started as a coaching chart rather than a research paper, and it reads slightly higher than Brzycki at low reps. For a single rep, the calculator uses the weight itself.
Source: Epley B. Poundage Chart. Boyd Epley Workout. Lincoln, NE: Body Enterprises; 1985.
Brzycki formula
1RM = w × 36 ÷ (37 − r)
Popular for bench press and designed for sets of up to 10 reps.
Source: Brzycki M. Strength testing: predicting a one-rep max from reps-to-fatigue. JOPERD. 1993;64(1):88-90.
Lander formula
1RM = 100 × w ÷ (101.3 − 2.67123 × r)
Source: Lander J. Maximum based on reps. NSCA Journal. 1985;6:60-61.
03 / Worked example
Worked examples
100 kg for 5 reps on the squat
You squat 100 kg for 5 hard reps and think you had one more rep left at most.
- 1Epley: 100 × (1 + 5 ÷ 30) = 116.7 kg
- 2Brzycki: 100 × 36 ÷ (37 − 5) = 112.5 kg
- 3Lander: 100 × 100 ÷ (101.3 − 13.36) = 113.7 kg
- 4Average: (116.7 + 112.5 + 113.7) ÷ 3 = 114.3 kg
Estimated squat 1RM: about 114 kg. A 5×5 at 80% would use about 92.5 kg.
225 lb for 8 reps on the bench press
You bench 225 lb for 8 reps.
- 1Epley: 225 × (1 + 8 ÷ 30) = 285.0 lb
- 2Brzycki: 225 × 36 ÷ 29 = 279.3 lb
- 3Lander: 22,500 ÷ 79.93 = 281.5 lb
- 4Average ≈ 281.9 lb
Estimated bench 1RM: about 280 lb.
04 / Reference
One-rep max charts and tables
| % of 1RM | Typical max reps | Load for a 100 kg 1RM | Load for a 225 lb 1RM |
|---|---|---|---|
| 100% | 1 | 100 kg | 225 lb |
| 95% | 2 | 95 kg | 215 lb |
| 93% | 3 | 93 kg | 210 lb |
| 90% | 4 | 90 kg | 205 lb |
| 87% | 5 | 87 kg | 195 lb |
| 85% | 6 | 85 kg | 190 lb |
| 83% | 7 | 83 kg | 185 lb |
| 80% | 8 | 80 kg | 180 lb |
| 77% | 9 | 77 kg | 175 lb |
| 75% | 10 | 75 kg | 170 lb |
| 70% | 11 | 70 kg | 160 lb |
| 67% | 12 | 67 kg | 150 lb |
| 65% | 15 | 65 kg | 145 lb |
Pound loads rounded to the nearest 5 lb. Rep counts are averages from the NSCA textbook table (NSCA’s own load chart puts 12 reps nearer 70%); people differ, and most can do more reps than listed on lower-body lifts such as the leg press.
Source: Baechle TR, Earle RW, eds. Essentials of Strength Training and Conditioning. 3rd ed. NSCA / Human Kinetics; 2008. %1RM–repetition relationship table.
| Goal | % of 1RM | Reps per set | Sets |
|---|---|---|---|
| Strength | 85% or more | 6 or fewer | 2–6 |
| Muscle growth (hypertrophy) | 67–85% | 6–12 | 3–6 |
| Muscular endurance | 67% or less | 12 or more | 2–3 |
Source: Baechle TR, Earle RW, eds. Essentials of Strength Training and Conditioning. 3rd ed. NSCA / Human Kinetics; 2008. Load and repetition assignments by training goal.
05 / Training
How to use your one-rep max
- Plan your working weights. Most programmes are written as percentages: "4 sets of 6 at 80%" means 80% of your 1RM. Use the training table in the result instead of guessing.
- Retest with a new rep-max set every 4 to 8 weeks, not with a true single. A hard set of 3 to 5 reps is safer, needs no spotter drama and gives a good estimate.
- Leave a rep or two in the tank most of the time. Lifting close to, but not always to, failure is enough for most people to build muscle. See how hard you should be training.
- Keep the same lift and technique when you compare. A paused bench, a belt, or a deeper squat all change the number.
- Track it for the big lifts: barbell bench press, barbell squats, barbell deadlift and the standing barbell shoulder press. Then see how your lifts compare with the strength standards calculator.
06 / Limitations
Limitations and safety
Every formula is an estimate. Studies comparing them with measured maxes found they are most accurate for sets of fewer than 10 reps; above that, errors grow, and they vary between lifts and between people (endurance-trained lifters tend to get more reps at a given percentage). In one study of college lifters, every equation tested underestimated the deadlift.
Do not attempt a true 1RM without warming up properly, using safety bars or a spotter, and having solid technique. Beginners do not need to test a 1RM at all.
This calculator gives an estimate for general fitness education. It is not medical advice and does not diagnose anything. If you have a health condition, are pregnant, or are new to hard exercise, check with a doctor first.
07 / FAQ
Frequently asked questions
What is a one-rep max?
Your one-rep max (1RM) is the most weight you can lift for one complete repetition of an exercise with good form. Coaches use it to set training loads as percentages.
Which 1RM formula is most accurate?
No single formula wins for every lift and person. Epley, Brzycki and Lander give very similar answers for sets of up to about 10 reps, which is why this calculator shows all three and uses their average. Accuracy depends more on using a hard set of 3 to 8 reps than on the formula.
How many reps should I use to estimate my 1RM?
A set of 3 to 8 reps taken close to failure works best. Estimates from sets above 10 reps become much less reliable, so the calculator stops at 12.
Is it safe to test a true one-rep max?
It can be for experienced lifters with good technique, a proper warm-up and safety bars or a spotter. Most people, and all beginners, get what they need from an estimated 1RM without the extra risk and fatigue of a true max.
How do I calculate 1RM in pounds?
Enter the weight in pounds and select pounds. The formulas work in any unit, so the estimate comes back in pounds: for example, 225 lb for 8 reps gives about 280 lb.
How often should I retest my 1RM?
Every 4 to 8 weeks, or at the end of a training block, is plenty. Re-estimating from a hard set of 3 to 5 reps is enough to update your training percentages.
What percentage of my 1RM should I lift to build muscle?
The NSCA suggests roughly 67 to 85% of your 1RM for 6 to 12 reps per set for muscle growth, and 85% or more for 6 reps or fewer for strength.
Sources
- Epley B. Poundage Chart. Boyd Epley Workout. Lincoln, NE: Body Enterprises; 1985.
- Brzycki M. Strength testing: predicting a one-rep max from reps-to-fatigue. J Phys Educ Recreat Dance. 1993;64(1):88-90.
- Lander J. Maximum based on reps. NSCA Journal. 1985;6:60-61.
- LeSuer DA, McCormick JH, Mayhew JL, Wasserstein RL, Arnold MD. The accuracy of prediction equations for estimating 1-RM performance in the bench press, squat, and deadlift. J Strength Cond Res. 1997;11(4):211-213.
- Baechle TR, Earle RW, eds. Essentials of Strength Training and Conditioning. 3rd ed. Champaign, IL: Human Kinetics / NSCA; 2008.
Related tools
- Strength Level CalculatorStrength standards by body weight: see how your bench, squat, deadlift and overhead press compare with your body weight, and your next milestone.
- Max Bench Press CalculatorEstimate your bench press max from a set of reps and see your bench training weights.
- TDEE CalculatorEstimate the calories you burn per day, then get a target for losing, keeping or gaining weight.
From the blog
Exercises to try
- Barbell Bench PressBeginner compound barbell exercise for the chest, also working the triceps and shoulders.
- Barbell SquatsBeginner compound barbell exercise for the quadriceps, also working the glutes.
- Barbell DeadliftIntermediate compound barbell exercise for the hamstrings, also working the glutes, abs and calves.
- Standing Barbell Shoulder PressBeginner compound barbell exercise for the shoulders, also working the traps and triceps.
- Front Barbell SquatsIntermediate compound barbell exercise for the quadriceps, also working the glutes.
- Incline Bench PullBeginner isolation barbell exercise for the middle back, also working the lats and shoulders.
Let the app do the percentages
GymStreak logs every set in kg or lb and builds your workouts around your goal, so the next session is already planned.
