3 scientific formulas · weighted average · most accurate at 3–6 reps

RPE Calculator

An RPE calculator turns a set you have already done into an estimated one rep max. Enter the weight, the reps and how hard the set felt on the RPE scale (where 10 is a maximal effort and 8 leaves about 2 reps in the tank), and you get your projected max.

RPE based loading lets you autoregulate: instead of chasing a fixed weight, you train to a target effort and let the load adjust to how you feel that day.

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kg
start here
5 repsStrength
1 rep12 reps
Weighted estimate · 3 formulas
115.5
KILOGRAMS
Brzycki · 1993
112.5kg
Epley · 1985
116.7kg
Lombardi · 1976
117.5kg

RPE to percentage chart

The RPE scale maps onto a percentage of your one rep max. This chart shows the percentage for a single rep at each RPE; the calculator extends it across rep ranges.

RPE (1 rep)% of 1RM
RPE 10100%
RPE 9.598%
RPE 996%
RPE 892%
RPE 789%

Percentages are for a single rep. As reps increase at the same RPE, the percentage of your 1RM drops, which is why the calculator uses the full RPE and rep chart rather than this single-rep snapshot.

The basics

1RM, RM, %1RM: decoded.

Your 1RM (one-rep max, or one-repetition maximum) is the heaviest load you can lift once on a given exercise with clean form. It's the reference unit for maximal strength in the gym.

By extension, an nRM is the max load for n reps (your 10RM = the weight you can lift only 10 times). Percentages of 1RM (%1RM) are then used to program your loads by goal: strength, hypertrophy, endurance. This calculator estimates your 1RM from a sub-maximal set, with no risky max-out test.

Your load table, by % of 1RM

Click a zone or a row to apply it straight to the calculator.

→ Click a row to try it in the calculator
%LoadReps
100%116 kg1
95%110 kg2
92%106 kg3
89%103 kg4
86%99 kgCURRENT
83%96 kg6
81%94 kg7
79%91 kg8
76%88 kg9
74%86 kg10
71%82 kg11
68%79 kg12
65%75 kg15
One number, four uses

One number,
four training
decisions.

Your 1RM is not just an ego score. It is the base every training intensity is set from.

01 · Program your intensities

Every set as a % of your 1RM: you know exactly what load to use for strength, hypertrophy or endurance.

02 · Track your progress

A stable benchmark over time. Compare your estimated maxes from one cycle to the next, with no max-out test.

03 · Load without injury

No need to chase a true max every session. You drive the load from a submaximal set instead.

04 · Compare your lifts

Squat, bench, deadlift: place each lift against your bodyweight and balance your program.

The science

Brzycki, Epley, Lombardi the science behind .

Edit the weight or reps right inside the formulas: the result recalculates live.

Brzycki1993
1RM = poids × 36 / (37 − reps)
with your values
1RM = × 36 / (37 − )
=112.5kg

The coaches' reference. Especially accurate between 3 and 10 reps.

↳ Best for 3 to 10 reps
Epley1985
1RM = poids × (1 + reps / 30)
with your values
1RM = × (1 + / 30)
=116.7kg

The best known. Linear, reliable across a wide rep range.

↳ Versatile, all ranges
Lombardi1976
1RM = poids × reps^0,10
with your values
1RM = × ^0,10
=117.5kg

A power model. Holds up well on long sets.

↳ Best beyond 10 reps

Sources & formulas

Estimates rely on three validated scientific formulas, averaged together to smooth out their differences:

  • Epley (1985) : estimating the 1RM from the number of repetitions.
  • Brzycki (1993) : 1RM prediction, especially reliable from 3 to 10 repetitions.
  • Lombardi (1989) : a power formula suited to high-rep sets.
  • LeSuer et al. (1997) : comparative study validating the accuracy of these formulas.

Strength standards: StrengthLevel (over 48 million performances), cross-checked with ExRx.

Comparison

Why this calculator ?

Seven criteria, three calculators. Click a row to see the feature.

Fit'Distance
0/7
Fit'Distance
0/7
ExRx.net
0/7
Calculator.net
CriterionFit'DistanceExRx.netCalculator.net
Number of formulassee →3 averaged2 (Brzycki + Baechle)3 (separate)
Real-time load tablesee →13 interactive levelsStatic tableNo
Strength level gaugesee →3 lifts × 5 levelsNoNo
Multi-lift SBD modesee →YesNoNo
Barbell loading viewsee →Yes (with plates)NoNo
Ads / pop-upsNoneShoe bannersAdobe banners
Mobile interfacesee →Touch optimizedAcceptableBroken
Heads up

Before testing your true 1RM

  • Warm up properly. Mobility, progressive sets, muscle activation. Never cold.

  • A spotter or safety bars. Never attempt a true max alone, without a spotter or a safety rack.

  • Technique before load. If form breaks down, the rep does not count. Stop before something gives.

  • Not every session. A true strength test belongs every 8 to 12 weeks, not every week.

FAQ

Everything people ask us

What is RPE in lifting?
RPE stands for Rating of Perceived Exertion, a 1 to 10 scale for how hard a set feels. An RPE of 10 is a maximal effort with nothing left, while an RPE of 8 means you could have done about two more reps.
How does the RPE calculator estimate my 1RM?
It takes your weight, reps and RPE, looks up the matching percentage of your one rep max on the RPE chart, and works back to your estimated 1RM. It is a quick way to gauge your max without a true maximal attempt.
What is RIR and how does it relate to RPE?
RIR means reps in reserve, the number of reps you had left. It is the mirror of RPE: RIR = 10 minus RPE. So RPE 8 is about 2 reps in reserve, and RPE 10 is 0 reps in reserve.
What exactly is a 1RM?
The 1RM (one-rep max) is the heaviest load you can lift once on a given exercise, with proper technique. It is the reference used to set all your training intensities as percentages.
Should I test my true 1RM or estimate it?
For most lifters, estimating from a submaximal set is safer and almost as accurate. A true 1-rep test carries injury risk and needs a long warm-up, a spotter and plenty of recovery.
Which formula is the most accurate?
None is perfect on its own. Brzycki is very reliable between 3 and 10 reps, Epley across a wide range, Lombardi beyond 10 reps. That is why we average all three: it smooths out the gaps.
How many reps should I use for a good estimate?
Between 3 and 6 reps gives the best accuracy. Beyond 10 reps the estimate becomes less reliable, as fatigue and technique distort the result.
Is the 1RM different per exercise?
Yes, completely. Your squat, bench press and deadlift 1RMs are independent. Calculate each one separately and compare it to your bodyweight with the strength gauge.
How often should I recalculate my 1RM?
Every 4 to 8 weeks, or at the end of each training block. Your strength changes, so your training percentages should follow to stay relevant.
Mathias Bradiceanu
Written and reviewed by
Mathias Bradiceanu
Founder & CEO at Fit'Distance

With 14 years of bodybuilding practice and a background as a military instructor, I'm now the founder of Fit'Distance. Passionate about sports performance optimization and entrepreneurship, I create tools to help sports coaches grow their business and help their clients progress intelligently.

Updated June 2026

1RM by exercise

CalculatorBench press 1RM calculatorCalculatorSquat 1RM calculatorCalculatorDeadlift 1RM calculator

Use it with your 1RM

StrengthRPE / RIR calculatorTune your loads to perceived effort.EnergyCooper simulatorEstimate your VO2 max and vVO2max.EnduranceBeep test simulatorGet your max speed from the shuttle run.PaceRunning pace tableConvert pace, speed and time.

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