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1RM Calculator: Find Your One Rep Max
This free 1RM calculator turns any set into your one rep max. Enter a weight and the reps you did to get your training weights and warm-up sets in seconds.
- 7 published formulas
- Works for any lift
- Your numbers stay in your browser
Your estimated 1RM
0 lb
How do I use this 1RM calculator?
This 1RM calculator works out the heaviest weight you could likely lift for one rep, using a set you have already done. You do not need to test a true max. It takes about 30 seconds.
- Pick your liftChoose bench press, squat, deadlift or any other exercise. For weighted pull-ups and dips, add your bodyweight too.
- Enter your setType the weight and the reps you finished with good form. A set of 2 to 10 reps works best.
- Add RPE if you likeIf you stopped with reps left in the tank, pick how hard the set felt. We add those reps back.
- Get your numbersSee your estimated max, training weights from 50% to 100%, rep maxes, warm-ups and the plates to load.
Switch to Coach mode to see every formula side by side, your 2RM to 12RM, and a warm-up ramp. Tap any weight in the tables to see how to load it on the bar. Your last 10 results are saved in your own browser, not on our server.
What can this max calculator do?
It is more than a single number. Along with your estimated max, you get everything you need to plan a session:
- Any exercise: barbell lifts, machines such as the leg press and lat pulldown, dumbbell lifts (entered per hand), and weighted pull-ups, chin-ups and dips with your bodyweight counted in. It works as a max lift calculator for almost anything you can do for reps.
- Training weights: 50% to 100% of your max, rounded to real plates, with the rep range each weight is usually used for.
- All formulas: see each of the seven estimates and how far it sits from the average.
- Rep maxes: your estimated 2RM to 12RM, so it also works as a rep calculator for any set.
- Warm-up sets: a ramp from the empty bar to your top set.
- Plate loading: tap any weight to see which plates go on each side, with a 45 lb, 35 lb, 20 kg, 15 kg or custom bar.
- Save and share: copy your result, print it, or share a link that opens with your numbers filled in.
Everything works offline once the page has loaded, so it is handy in a basement gym with poor signal.
What do “max”, “1RM” and “PR” mean?
Lifters use a few words for the same idea. Here is what each one means.
- One rep max (1RM or ORM): the most weight you can lift once, with good form, for a given exercise. It is also called your “max”. An ORM calculator and a 1RM calculator are the same thing.
- PR (personal record) or PB (personal best): the best you have ever done. A PR can be a 1RM, but it can also be your best set of 5 or 10. A PR calculator or PB calculator is another name for this tool.
- Estimated, projected, predicted or calculated max: a 1RM worked out from a lighter set, like the one this one rep max estimator gives you. Weightlifting coaches and powerlifters use the same idea.
- Rep max (RM): the most weight you can lift for a set number of reps. Your 5RM is the heaviest weight you can lift 5 times.
So when you ask “what’s my max?”, this page gives you an estimated 1RM from any set. Read more in our guide: what is one rep max.
Which formulas does the 1RM calculator use?
Researchers and coaches have written several equations that turn a set of reps into a 1RM. None is perfect, so we run your set through seven of them and show the average as your headline number. You can switch to any single formula in Coach mode. In each formula, w is the weight you lifted and r is the reps you did.
Epley (1985)
1RM = w × (1 + r ÷ 30)
Example: 100 kg × 5 reps = 100 × (1 + 5 ÷ 30) = 116.7 kg
Brzycki (1993)
1RM = w × 36 ÷ (37 − r)
Example: 100 kg × 5 reps = 100 × 36 ÷ 32 = 112.5 kg
Lander (1985)
1RM = 100 × w ÷ (101.3 − 2.67123 × r)
Example: 100 kg × 5 reps = 113.7 kg
Lombardi (1989)
1RM = w × r0.10
Example: 100 kg × 5 reps = 117.5 kg
Mayhew et al. (1992)
1RM = 100 × w ÷ (52.2 + 41.9 × e−0.055 × r)
Example: 100 kg × 5 reps = 119 kg
O’Conner et al. (1989)
1RM = w × (1 + 0.025 × r)
Example: 100 kg × 5 reps = 112.5 kg
Wathan (1994)
1RM = 100 × w ÷ (48.8 + 53.8 × e−0.075 × r)
Example: 100 kg × 5 reps = 116.6 kg
You may also see the McGlothin formula. Once you simplify it, it is the same equation as Lander, so we do not list it twice. When you enter 1 rep, every formula returns the weight you lifted, because a single rep already is your max for that day.
Here is the same idea in pounds. A lifter who benches 225 lb for 5 reps gets these estimates:
| Formula | Estimated 1RM | vs average |
|---|---|---|
| Epley | 262.5 lb | +2.6 lb |
| Brzycki | 253.1 lb | −6.7 lb |
| Lander | 255.8 lb | −4 lb |
| Lombardi | 264.3 lb | +4.4 lb |
| Mayhew et al. | 267.8 lb | +7.9 lb |
| O’Conner et al. | 253.1 lb | −6.7 lb |
| Wathan | 262.3 lb | +2.5 lb |
| Average | 259.9 lb | – |
The spread is about 253.1 to 267.8 lb. That gap is why we show a range under your result. The average, 259.9 lb, is a sensible middle. Want to do this by hand? Our guide on how to calculate one rep max walks through every step.
Formula comparison table
Some formulas read higher than others. This table shows how far each one sits from the average at 5 and 10 reps, so you know which way a single formula leans before you pick it in Coach mode.
| Formula | Year | At 5 reps | At 10 reps | Tends to read | Notes |
|---|---|---|---|---|---|
| Epley | 1985 | +1.0% | +1.7% | Close to average | Straight line: adds about 3.3% per rep. |
| Brzycki | 1993 | −2.6% | +1.7% | Close to average | Climbs faster as reps rise. Breaks down near 37 reps. |
| Lander | 1985 | −1.5% | +2.3% | Close to average | Same equation as McGlothin once simplified. |
| Lombardi | 1989 | +1.7% | −3.9% | Close to average | Power curve that rises gently with reps. |
| Mayhew et al. | 1992 | +3.0% | −0.1% | Close to average | From a study of bench press strength. |
| O’Conner et al. | 1989 | −2.6% | −4.6% | Reads low | Straight line: adds 2.5% per rep. |
| Wathan | 1994 | +0.9% | +2.8% | Reads high | Curve published in an NSCA textbook chapter. |
Which formula should I trust for my lift?
For most people the average is the safest choice, because it smooths out the formulas that run high or low. A few practical points help too:
- Use a heavy set. A study of bench press and leg press found that the 5RM gave the most accurate 1RM prediction, better than sets of 10 or 20 reps (Reynolds and colleagues, 2006).
- Deadlifts run low. In a study of seven common equations, every one of them underestimated the deadlift, even though the predictions tracked the real maxes closely (LeSuer and colleagues, 1997). If your deadlift estimate feels light, it may well be.
- Bench and squat vary by formula. In the same study, most equations were off by a meaningful amount on average for the bench and squat, which is another reason to look at the range and not one number.
- Fast lifts are different. Cleans and snatches depend on speed and skill, so estimates from high reps are less useful. Use sets of 1 to 3 for those.
Each lift has its own calculator with presets and tips: the bench press calculator, squat calculator and deadlift calculator.
Not sure which lift to start with? The 1RM calculator above works for any exercise, and each lift page gives you a one rep max calculator set up for that lift.
How accurate is an estimated one rep max?
An estimated max is a good guide, not a promise. It is usually closest when your set is 2 to 6 reps and taken close to failure. It gets less reliable above 10 reps, which is why the 1RM calculator shows a warning there. Your real max also moves from day to day with sleep, food, stress and technique.
Two people who lift the same weight for the same reps can have different true maxes. Someone built for endurance may do more reps at a given percentage than someone built for strength. That is normal. Use the estimate to plan training, then adjust by feel. Our guide on how accurate 1RM calculators are covers the research in more detail.
How do I convert a 3RM, 5RM or 10RM to a 1RM?
This rep max calculator converts in any direction. Enter a rep max (for example your 3RM or 10RM) to get your 1RM and every rep max from 1 to 20. Add target reps to find the weight for a new set, or add a weight to see how many reps you could likely do with it.
Some quick examples from the same engine:
- 3 rep max to 1 rep max: 100 kg × 3 reps works out to about 109.3 kg.
- 5RM to 1RM: 225 lb × 5 reps works out to about 259.9 lb.
- 8 rep max to 1 rep max: 185 lb × 8 reps works out to about 230.7 lb.
- 10 rep max: 60 kg × 10 reps works out to about 78.6 kg.
- Reps to max the other way: with a 300 lb max, your 5RM is about 259.9 lb and your 10RM about 229.1 lb.
How do I use my 1RM in training?
Most strength programs set weights as a percentage of your 1RM. Heavier percentages allow fewer reps. The 1RM calculator’s Training weights table shows 50% to 100% of your max, rounded to plates you can load. Here is an example for a 300 lb max:
| % of 1RM | Weight | Reps (approx.) | Often used for |
|---|---|---|---|
| 100% | 300 lb | 1 | Max strength |
| 95% | 285 lb | ~2 | Max strength |
| 90% | 270 lb | ~4 | Max strength |
| 85% | 255 lb | ~6 | Strength |
| 80% | 240 lb | ~8 | Strength |
| 75% | 225 lb | ~11 | Hypertrophy |
| 70% | 210 lb | ~14 | Hypertrophy |
| 65% | 195 lb | ~17 | Size + endurance |
| 60% | 180 lb | ~20 | Size + endurance |
| 55% | 165 lb | 20+ | Warm-up |
| 50% | 150 lb | 20+ | Warm-up |
Our reps column comes from the formula average. The National Strength and Conditioning Association (NSCA) publishes a similar chart. Here it is next to our numbers, so you can see how close they are:
| Max reps | % of 1RM | Our engine average |
|---|---|---|
| 1 | 100% | 100.0% |
| 2 | 95% | 94.3% |
| 3 | 93% | 91.5% |
| 4 | 90% | 89.0% |
| 5 | 87% | 86.6% |
| 6 | 85% | 84.4% |
| 7 | 83% | 82.3% |
| 8 | 80% | 80.2% |
| 9 | 77% | 78.3% |
| 10 | 75% | 76.4% |
| 12 | 70% | 72.8% |
How you use these zones depends on your goal. The American College of Sports Medicine suggests loads of about an 8 to 12 rep max for new lifters. For more experienced lifters it suggests a wider range of 1 to 12 reps over time, with more heavy work in the 1 to 6 rep range for strength. For a printable version, see the one rep max chart. If your strength changes from day to day, try the RPE calculator, which picks weights from how hard a set feels.
Should I test my max or estimate it?
For most lifters, estimating is the smarter choice. A true 1RM test is hard on your body, needs a spotter or safety pins, and tells you your max on one day only. An estimate from a heavy set of 3 to 5 gives you almost the same information with far less risk.
Testing makes sense if you compete in powerlifting, or if you have trained for a while with good technique and want a real number. If you do test, warm up well, use safety arms or a trained spotter, and stop if your form breaks down. New lifters do not need a true max at all. Read our step-by-step guide on how to test your 1RM safely.
Safety first: every number here is an estimate. Lift heavy with a spotter or safety pins, stop if you feel pain, and check with a doctor before heavy lifting if you have an injury, a heart condition or are pregnant.
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Frequently asked questions
What is a 1RM calculator?
A 1RM calculator estimates the heaviest weight you can lift for one repetition. You enter a weight and the reps you completed, and it applies published formulas such as Epley and Brzycki. It saves you from testing a true max, which is tiring and riskier.
How do I calculate my one rep max by hand?
The simplest way is the Epley formula: multiply the weight by (1 + reps ÷ 30). For 100 kg for 5 reps, that is 100 × 1.167 = about 116.7 kg. Other formulas give slightly different answers, so the 1RM calculator averages seven of them.
Which 1RM formula is the most accurate?
No single formula wins for every lift and every person. Studies show different equations fit different lifts, and all of them tended to underestimate the deadlift in one study. Using the average of several formulas, from a heavy set of 2 to 6 reps, is a practical choice.
How many reps should I use for the most accurate estimate?
Use a set of 2 to 10 reps, ideally 3 to 5, taken close to failure with good form. One study found a 5-rep max predicted the 1RM more accurately than sets of 10 or 20. Above 10 reps, estimates get less reliable.
Is a max rep calculator the same as a one rep max calculator?
Yes, people use both names. A max rep calculator, rep max calculator or max weight calculator usually means a tool that turns a set of several reps into your one rep max. This page does that and also converts your 1RM back into weights for any number of reps.
Does the 1RM calculator work in both pounds and kilograms?
Yes. Switch between lb and kg at the top of the calculator. Your choice is remembered in your browser. Every result also shows the other unit, and training weights are rounded to plates you can load, such as 5 lb or 2.5 kg.
What is a good one rep max?
It depends on your bodyweight, sex, age and training history. A good max is one that keeps going up over time. If you compete in powerlifting, the Wilks, DOTS and IPF GL scores let you compare lifters of different sizes on our Wilks calculator.
How often should I test my 1RM?
Most lifters do not need to test often. Many only test at the end of a training block or before a competition. You can re-estimate any time from a heavy set, which is much easier on your body and gives you a number to plan with.
Is my data stored or shared?
No. The maths runs in your own browser. Your last 10 results are kept only in your browser so you can see your progress. We do not receive your weights or reps.
Should beginners test a one rep max?
No. Beginners get stronger quickly and are still learning technique, so a true max test adds risk without much benefit. Use this calculator with a set of 5 to 10 reps and build strength with good form first.
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. Journal of Physical Education, Recreation & Dance. 1993;64(1):88-90.
- Lander J. Maximum based on reps. National Strength and Conditioning Association Journal. 1985;6(6):60-61.
- Lombardi VP. Beginning Weight Training. Dubuque, IA: W.C. Brown; 1989.
- Mayhew JL, Ball TE, Arnold MD, Bowen JC. Relative muscular endurance performance as a predictor of bench press strength in college men and women. Journal of Applied Sport Science Research. 1992;6(4):200-206.
- O’Conner B, Simmons J, O’Shea P. Weight Training Today. St. Paul, MN: West Publishing; 1989.
- Wathan D. Load assignment. In: Baechle TR, ed. Essentials of Strength Training and Conditioning. Champaign, IL: Human Kinetics; 1994:435-446.
- 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. Journal of Strength and Conditioning Research. 1997;11(4):211-213. Abstract
- Reynolds JM, Gordon TJ, Robergs RA. Prediction of one repetition maximum strength from multiple repetition maximum testing and anthropometry. Journal of Strength and Conditioning Research. 2006;20(3):584-592. PubMed 16937972
- American College of Sports Medicine. Position stand: Progression models in resistance training for healthy adults. Medicine & Science in Sports & Exercise. 2009;41(3):687-708. PubMed 19204579
- National Strength and Conditioning Association. Training Load Chart. NSCA (PDF)