A 5 rep max (5RM) is the heaviest weight you can lift for exactly 5 reps with acceptable form. If you can do a sixth rep, the weight was below your 5RM. This calculator estimates it; it does not replace a real set.

How do I calculate my 1RM from my 5RM?

Choose "I lifted a set", enter the weight, keep the reps at 5 and leave the effort on "To failure". The weight you lifted is your 5RM, and seven published equations turn it into a 1RM estimate. For a set of 5, they put the 1RM about 13% to 19% above the weight lifted.

What percentage of my 1RM is my 5RM?

It depends on the equation. The seven equations in LeSuer's table give about 84% to 88.9% for 5 reps, and the Helms RPE chart gives 85% at RPE 10. A flat 87% rule is a common shortcut, but it matches only some of the equations.

How do I calculate my 5RM from my 1RM?

Choose "I know my 1RM", enter it and read the 5RM. The calculator runs each equation in reverse, which is plain arithmetic on a formula built for the other direction. I found no study that tested the reverse direction, so treat it as the less certain of the two.

Which formula is the most accurate?

The studies I read do not name one. In a study of 67 untrained college students, only Mayhew and Wathan did not differ significantly from the measured bench press 1RM, and only Wathan did for the squat. All seven came out low for the deadlift, so the page shows the range across all seven.

Does my 5RM have to be a set to failure?

Yes, for the seven equations. They were built from reps to fatigue, so a set that stopped short reads too low. If you pick a lower effort, the page switches to the Helms RPE chart for the estimate and says so.

Why does the calculator stop at 10 reps?

The equations were built on sets of about 10 reps or fewer. Brzycki says his is only valid below 10 reps, Reynolds and colleagues advise no more than 10 reps in linear equations, and Mayhew's study found better accuracy below 10 reps to fatigue. Beyond that I have no source that supports the numbers.

What does the Reynolds check show?

For a real set of 5 to failure on the bench press or leg press, the page also applies a regression fitted to measured data from 70 adults: 1RM = 1.1307 × 5RM + 0.6999 for the bench press and 1RM = 1.097 × 5RM + 14.2546 for the leg press, in kg. The standard errors were 2.98 kg and 16.16 kg, and reps were paced to a metronome at 30 a minute. It is not applied to other lifts because the study did not test them.

Is it accurate for deadlifts?

Treat it with extra care. In LeSuer's study of untrained students, all seven equations came out 9 to 14% below the measured deadlift 1RM on average. The calculator adds that warning when you pick the deadlift and does not try to correct for it.

Does it work for all ages?

The sources included men and women, adults aged 18 to 69. I did not verify data for teenagers or for people over 70. If you enter an age outside 18 to 69, the calculator shows a warning.

How do I test my 5RM for real?

I did not find a protocol written for a 5RM in a primary source, so I do not give one. The Australian Institute of Sport manual covers 1RM, 3RM and 6RM tests, and the page summarises its bench press warm-up and attempt rules. Use the estimate as a starting load and use spotters or safety bars.

Is a 5RM test safer than a 1RM test?

One small study of 34 healthy young men who had not strength trained for a year reported no soreness or limited exercise after 4 to 6RM and 7 to 10RM tests. After a 1RM test it reported soreness in 21 men (61.2%) and limited exercise in 6 (17.5%). It tested 4 to 6 reps, not 5 exactly, and one kind of lifter, so this page makes no general safety claim.

Is my 5RM the weight for 5x5?

Not on its own. A 5RM is one maximal set of five and says nothing about repeating that weight for five sets. I found no source for a standard 5x5 percentage, so I do not give one.

Why do other 5RM calculators give a different number?

Some use a single equation, some use a different set of equations, and some multiply a 1RM by a fixed 87%. At 5 reps the seven equations here span about 5 percentage points of 1RM (84% to 88.9%), so the choice matters. This page shows each equation separately so you can see the spread.

5 Rep Max Calculator: Estimate Your 5RM and 1RM

Name: 5 Rep Max Calculator
Author: Manish Kumar

Key Takeaways

Your 5RM is the heaviest weight you can lift for 5 reps. This calculator estimates it from a hard set of 2 to 10 reps or from a 1RM, using seven published equations^[2]. If you enter a real set of 5 to failure, the 5RM is the weight you lifted and the page estimates your 1RM instead.
Five reps is not a fixed share of the 1RM. The seven equations put it at 84% to 88.9%, and a published RPE chart gives 85%^[2]^[6]. A flat 87% rule fits some equations and misses others.
A real 5RM predicts a 1RM well. In 70 adults it beat a 10RM and a 20RM, and the authors published a bench press and a leg press equation^[3]. The page shows the equation as a second opinion.
Treat the result as an estimate. The Australian Institute of Sport testing manual puts the variability of submaximal predictions at about 10%^[9], and in one study all seven equations came out low for the deadlift^[2].
I couldn't source strength standards, training zones, a 5x5 percentage or a 5RM test protocol, so they aren't here. The last section says what else is missing.

What a 5RM Is, and What It Is Not

A 5 rep max (5RM) is the heaviest weight you can lift for 5 reps in one set, with form you would accept in training. If a sixth rep is possible, the weight was below your 5RM.

It describes a single maximal set. It says nothing about repeating that weight across several sets, so it isn't a 5x5 working weight on its own.

Is a rep-max test gentler than a 1RM test?

One small study points that way. It tested 34 healthy men aged 19 to 32 who had done no strength training for a year. After their 4 to 6RM and 7 to 10RM tests, none reported soreness or limited exercise^[4].

After the 1RM test, 6 men (17.5%) reported limited exercise and 21 (61.2%) reported soreness, as the study reports them. It's one small sample of untrained men, and it tested 4 to 6 reps, not 5 exactly, so take it as a hint.

How the Estimate Works

Each of these equations was written to turn a set taken to fatigue into a 1RM. The calculator runs it forward to get a 1RM, then backward to get the load for 5 reps.

What happens when you press Calculate

Each equation turns your weight and reps into a 1RM estimate.
The same equation then divides that 1RM by its own 5-rep factor to get a 5RM.
The page shows the lowest, highest and average of the seven answers.
For comparison, it applies the Helms chart, which puts 5 reps at RPE 10 at 85% of 1RM^[6].

With a set of exactly 5 to failure, the two steps cancel and you get your own weight back as the 5RM. The page then estimates your 1RM instead.

LeSuer and colleagues print the seven equations in their Table 1^[2]. Here they are, with the share of 1RM each gives for 5 reps and the 1RM that follows from a 5RM of 100:

Equation	Form	5 reps as % of 1RM	1RM from a 5RM of 100	Original publication
Epley	1RM = w × (1 + 0.0333 × r)	85.7%	116.7	Epley, Poundage Chart, 1985 (not opened)
Brzycki	1RM = 100 × w ÷ (102.78 − 2.78 × r)	88.9%	112.5	Brzycki, 1993 (opened and checked)
Lander	1RM = 100 × w ÷ (101.3 − 2.67123 × r)	87.9%	113.7	Lander, NSCA Journal, 1985 (not opened)
Lombardi	1RM = w × r^0.1	85.1%	117.5	Lombardi, Beginning Weight Training, 1989 (not opened)
Mayhew	1RM = 100 × w ÷ (52.2 + 41.9 × e^(−0.055 × r))	84%	119	Mayhew et al., J Appl Sport Sci Res, 1992 (not opened)
O'Conner	1RM = w × (1 + 0.025 × r)	88.9%	112.5	O'Conner et al., Weight Training Today, 1989 (not opened)
Wathan	1RM = 100 × w ÷ (48.8 + 53.8 × e^(−0.075 × r))	85.8%	116.6	Wathan, in Baechle (ed.), 1994 (not opened)

w is the weight lifted and r is the reps to fatigue. The last two columns are arithmetic on each equation at 5 reps.

Brzycki's paper has its own table for this equation. A 100 lb set of 5 predicts a 1RM of 112 lb, and 225 lb for 10 reps predicts about 300 lb^[1]. The calculator reproduces those values in its tests.

Brzycki didn't fit his equation to lifters he tested. He anchored it on an unpublished observation, passed on through a 1981 review, that about 10 reps can be done at roughly 75% of a max^[1].

I opened only Brzycki's paper. The other six equations come from LeSuer's table, and I didn't open their original publications, so I can't say how they were derived.

Worked example: 100 kg for 3 reps to failure

Brzycki 1RM = 100 × 100 ÷ (102.78 − 2.78 × 3) = 105.9 kg

Brzycki 5RM = 105.9 ÷ (100 ÷ (102.78 − 2.78 × 5)) = 94.1 kg

Epley 1RM = 100 × (1 + 0.0333 × 3) = 110 kg

Epley 5RM = 110 ÷ (1 + 0.0333 × 5) = 94.3 kg

Average of all seven: 5RM 94.6 kg, range 93.5 to 95.8 kg

The average is there because most people want one number. The studies I read don't name a best equation, and I found no test of the average itself, so lean on the range.

Converting a 5RM to a 1RM, and Back

Enter a set of 5 reps to failure and the page gives the 1RM. Multiply the 5RM by the factor for any equation to do it by hand: 1.13 to 1.19, depending on which one you pick.

5RM (kg)	Average 1RM (kg)	Range (kg)
40	46.2	45 to 47.6
60	69.3	67.5 to 71.4
80	92.4	90 to 95.2
100	115.5	112.5 to 119
120	138.6	135 to 142.8
140	161.7	157.5 to 166.6

1RM estimated from a 5RM to failure, in kg. Average and range of the seven equations.

For the reverse, switch to "I know my 1RM". That direction is arithmetic on the same equations, and I found no study that tested it, so it's the less certain of the two.

Measured data covers the forward direction for two lifts. Reynolds and colleagues fitted a line through real 5RM and 1RM results, with reps paced to a metronome at 30 a minute^[3]:

Lift	1RM from 5RM	Standard error	R²
Flat barbell bench press	1.1307 × 5RM + 0.6999	2.98 kg	0.993
Plate-loaded leg press	1.0970 × 5RM + 14.2546	16.16 kg	0.974

Reynolds et al. (2006). 70 adults aged 18 to 69. Weights in kg.

The calculator shows this line only for a real set of 5 to failure on the bench press or leg press. It doesn't apply it to other lifts, because the study didn't test them.

How Accurate Is It?

This is what each source looked at, so you can judge how far to trust a number:

Source	What it found	Limit
LeSuer et al., 1997^[2]	67 untrained college students (40 men, 27 women; some skipped the squat and deadlift) did a 1RM and a set of 10 or fewer reps to fatigue. All seven equations correlated highly with the measured 1RM (r above 0.95). Bench press: only Mayhew and Wathan did not differ significantly from the measured 1RM, and the other five came out 1 to 6% low on average. Squat: only Wathan did not differ, and the others were 3 to 8% low. Deadlift: all seven were low, by 9 to 14%.	Untrained students. Predicted a 1RM, not a 5RM.
Reynolds et al., 2006^[3]	70 people aged 18 to 69 did 1, 5, 10 and 20RM tests on the barbell bench press and a plate-loaded leg press. R² for predicting the 1RM: 5RM 0.993 bench and 0.974 leg press; 10RM 0.976 and 0.933; 20RM 0.955 and 0.915. The authors advise no more than 10 reps in linear equations.	Bench press and leg press only. 5RM to 1RM, not the reverse. Reps were metronome-paced.
Dohoney et al., 2002^[4]	34 healthy men aged 19 to 32 did 1RM, 4 to 6RM and 7 to 10RM tests on five exercises. The 4 to 6RM equations predicted the 1RM more accurately than the 7 to 10RM ones. I also cite its soreness figures above.	Men only, untrained, 4 to 6RM and not 5RM. I didn't use its equations because I couldn't confirm their units.
Mayhew et al., 2008^[5]	103 young women did bench press tests before and after 12 weeks of training. Prediction equations were more accurate when fewer than 10 reps to fatigue were used.	Young women, bench press only.
Australian Institute of Sport, 2022^[9]	Its testing manual says prediction equations are influenced by the muscle group, the exercise and training level, with large variability (about 10%) when submaximal reps predict a maximum. When recording test results, it says to log the weight and reps actually lifted and not to use predictive equations to calculate a 1RM.	A testing manual that cites earlier studies, not a new experiment. Written for formal athlete testing.

Use a heavy set with few reps. Brzycki says his equation is only valid below 10 reps to fatigue^[1]. LeSuer describes the equations as built on 10 or fewer^[2], Reynolds advises no more than 10^[3], and Mayhew found better accuracy below 10^[5]. So the calculator accepts 2 to 10 reps and warns at 8 or more.
The set must go to failure. The equations assume reps to fatigue. If you stopped with reps left, the estimate reads low, which is why the page offers an RPE option.
Lifters misjudge failure. A pooled analysis of 12 studies (414 people) found lifters under-predicted their reps in reserve by about 1 rep on average, with large differences between studies^[8]. I don't know how that carries over to a set you call "failure", so the page makes no adjustment for it.
A 5RM from another set size is a stretch. The studies check the 1RM that comes out. I found none that checks a 5RM taken from the same equation, so a 5RM from a set of 3 or 8 can be off by an amount I can't quote.
Who was studied. Mostly students and adults aged 18 to 69^[2]^[3]. Accuracy data cover the bench press, squat and deadlift, plus the leg press. I found no data for teenagers, people over 70 or other lifts, so the calculator warns outside 18 to 69.

5RM as a Percentage of 1RM

Many calculators use one flat figure, often around 87%, for a 5RM. The seven equations give 84% to 88.9% at 5 reps, so a single number fits some and misses others by several points^[2].

The Helms chart gives another view. For 5 reps it lists a share of 1RM at each RPE, from RPE 10 (no reps left) down to RPE 7 (about 3 reps left)^[6]^[7]:

RPE	10	9.5	9	8.5	8	7.5	7
5 reps, % of 1RM	85%	84%	83%	82%	81%	80%	79%

Estimated % of 1RM for 5 reps by RPE (Helms et al., 2016, Table 2). Almost all of the chart is estimated, not measured.

That is why the calculator offers an RPE choice. If your set stopped short of failure, the seven equations would read low, so the page uses this chart instead and says so. To work out your RPE from reps in reserve, use the RIR to RPE Calculator.

Testing a 5RM for Real

I did not find a protocol written for a 5RM in a primary source. The Australian Institute of Sport testing manual covers 1RM, 3RM and 6RM, and it is the closest published guide I could open^[9].

Its bench press warm-up uses lighter sets with fewer reps each time, as a percentage of the load you expect to lift:

Set	% of predicted RM	Reps for 3RM	Reps for 6RM
1	40–60%	12 or fewer	15 or fewer
2	60–70%	6 or fewer	10 or fewer
3	70–80%	6 or fewer	10 or fewer
4	90%	3–5	6–8

Bench press warm-up from the AIS manual. It has no 5RM column.

Attempts. After the warm-up, add load in steps such as 95%, 97.5% and 100% of the predicted load until the maximum is reached. The manual says to aim for the result within 4 trials, not counting the warm-up^[9].
Rest. For the bench press it gives 2 to 5 minutes between attempts, and at least 2 minutes between the earlier warm-up sets^[9].
Safety. It recommends two experienced spotters for maximal bench press efforts, and says the test ends once a technical violation is seen^[9].
Readiness. It suggests avoiding severe fatigue in the 72 hours before a test and practising the lift for at least 6 sessions first^[9].

The manual says to start from recent training data or an earlier result. The estimate from this page can serve as that starting load, with the error described above.

What About 5x5?

A 5RM is one maximal set of five. It says nothing about repeating that weight for five sets, so I don't treat it as a 5x5 working weight.

I found no source for a standard 5x5 percentage, so I don't give one. The RPE table above is one way in: five reps at RPE 8, with about two in reserve, is 81% of 1RM on the Helms chart^[6].

Using the Result

If you can, use a hard set of 4 to 6 reps. Dohoney's 4 to 6RM predicted a 1RM better than a 7 to 10RM^[4], and Reynolds' 5RM beat the 10RM and 20RM^[3].
Read the range, not only the average. A wide range means less reason to trust any single number.
On the bench press or leg press with a real set of 5 to failure, compare the Reynolds check with the range. If it falls outside, treat the whole estimate as shakier.
Use the result as a starting load, not a verdict. The AIS manual says to record the weight and reps actually lifted^[9], and a rested, warmed-up set with a spotter or safety bars gives you that.
For a three-rep version, see the 3 Rep Max Calculator. To turn reps and effort into a load, use the RPE Calculator.

What This Page Doesn't Cover

I left these out because I couldn't trace them to a source I could open:

A fixed 0.87 factor. The equations disagree on the share of 1RM at 5 reps, and no single factor fits all seven.
Strength standards by level. I found no sourced 5RM standards, and any fixed table would ignore bodyweight.
Sets, reps and rest by percentage of 5RM. No primary source found.
Training claims about hypertrophy, periodization, rest-pause, pyramids or tempo. None tied to a specific study.
A 5RM test protocol or retest schedule. The AIS section above covers related tests, and I found nothing on how often to test a 5RM.

Also unverified: the original sources for the Epley, Lander, Lombardi, Mayhew, O'Conner and Wathan equations, which I read only through LeSuer. The AIS manual I used is version 2.0, and I didn't confirm whether a newer one exists.

Frequently Asked Questions

Sources & References

Strength testing: predicting a one-rep max from reps-to-fatigue. Brzycki M. Journal of Physical Education, Recreation & Dance 64(1):88-90 (1993)
The accuracy of prediction equations for estimating 1-RM performance in the bench press, squat, and deadlift. LeSuer DA, McCormick JH, Mayhew JL, Wasserstein RL, Arnold MD. Journal of Strength and Conditioning Research 11(4):211-213 (1997)
Prediction of one repetition maximum strength from multiple repetition maximum testing and anthropometry. Reynolds JM, Gordon TJ, Robergs RA. Journal of Strength and Conditioning Research 20(3):584-592 (2006)
Prediction of one repetition maximum (1-RM) strength from a 4-6 RM and a 7-10 RM submaximal strength test in healthy young adult males. Dohoney P, Chromiak JA, Lemire D, Abadie BR, Kovacs C. Journal of Exercise Physiology online 5(3):54-59 (2002)
Accuracy of prediction equations for determining one repetition maximum bench press in women before and after resistance training. Mayhew JL, Johnson BD, LaMonte MJ, Lauber D, Kemmler W. Journal of Strength and Conditioning Research 22(5):1570-1577 (2008)
Application of the repetitions in reserve-based rating of perceived exertion scale for resistance training. Helms ER, Cronin J, Storey A, Zourdos MC. Strength and Conditioning Journal 38(4):42-49 (2016)
Novel resistance training-specific rating of perceived exertion scale measuring repetitions in reserve. Zourdos MC, Klemp A, Dolan C, Quiles JM, Schau KA, Jo E, Helms E, Esgro B, Duncan S, Garcia Merino S, Blanco R. Journal of Strength and Conditioning Research 30(1):267-275 (2016)
Accuracy in predicting repetitions to task failure in resistance exercise: a scoping review and exploratory meta-analysis. Halperin I, Malleron T, Har-Nir I, Androulakis-Korakakis P, Wolf M, Fisher J, Steele J. Sports Medicine 52(2):377-390 (2022)
National Protocols for the Assessment of Strength and Power, Version 2.0 (effective July 2022). Australian Institute of Sport and the National Institute Network. Australian Sports Commission (2022)

Manish Kumar

Certified Personal Trainer & Sports Nutritionist

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NASM-certified fitness and nutrition coach with over 10 years of hands-on experience helping people build strength, lose fat, and live healthier lives. Specializing in gym-based workouts with a strong focus on lifting technique, biomechanics, and practical exercise science. Through FitLifeRegime, sharing the tools, tips, and insights that have worked for hundreds of clients — helping you start your own fitness journey with confidence and clarity.

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Disclaimer: This tool is for informational and personal journaling purposes only. Results are estimates based on published formulas and may vary based on individual factors such as genetics, training history, and measurement technique.

5 Rep Max Calculator

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