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One Rep Max Calculator

Estimate your true one rep max, training percentages, and strength zones using proven lifting formulas.

Epley · Brzycki · Lombardi, side-by-sideLast updated 2026-05-15

Training estimate only. Never attempt a true 1RM without a warm-up, a competent spotter, and at least 12 weeks of structured lifting experience.

kg
Best accuracy 1–10

Pick the number of full-range reps you completed at that weight. Estimates are most accurate between 1 and 10 reps.

What this tool computes

Three peer-reviewed equations — Epley, Brzycki and Lombardi — estimate the maximum weight you could lift for a single rep, and then derive training percentages, rep predictions and strength zones from that 1RM.

Enter the weight you lifted and the number of reps to estimate your one rep max, training percentages and strength zones.

What Is One Rep Max?

One rep max (1RM) is the maximum amount of weight you can lift for a single repetition of a given exercise with full range of motion and acceptable technique. It is the gold-standard measurement of pure strength in powerlifting, weightlifting and most strength-and-conditioning programmes.

Because a true 1RM is risky and fatiguing, coaches usually estimate it from a sub-maximal set. A 1RM calculator like this one takes the weight you lifted and how many reps you completed, and uses a published equation to project the single rep you could have performed. It is more practical, safer, and accurate enough for programming day-to-day training percentages.

Why Athletes Use 1RM

Once you know your 1RM, you can program every other set on the basis of that number. Most strength-and-conditioning systems — from Westside, 5/3/1 and Smolov to Conjugate, Sheiko and many CrossFit programmes — express daily prescriptions as a percentage of 1RM. That keeps load relative to current ability, scales automatically as you get stronger, and lets coaches compare athletes of different bodyweights on the same axis.

Programming with %1RM

Heavy strength work lives at 80–90%, hypertrophy at 65–80%, conditioning at 50–65%. Percentages make it possible to cycle intensity and volume without guessing.

Tracking real progress

A rising estimated 1RM at the same bodyweight is one of the clearest signals that your training is working — and a falling number can flag overreaching or under-recovery.

Epley vs Brzycki vs Lombardi

Each equation was calibrated on a different dataset and produces slightly different 1RM estimates for the same input. None of them is universally "right" — they bracket the real value.

Epley · Default

The most widely cited formula. Sits in the middle of the three across most rep ranges and is the basis of countless training spreadsheets.

1RM = W × (1 + R / 30)

Brzycki

Tends to give the most conservative 1RM, especially at higher rep counts. Very accurate inside 1–6 reps and popular in tactical fitness testing.

1RM = W × 36 / (37 − R)

Lombardi

A power-law equation. Behaves more smoothly across the full 1–20 rep range and is frequently used in CrossFit and conjugate programming.

1RM = W × R^0.10

W = weight lifted · R = number of reps performed. Results are rounded to one decimal place.

How To Increase Your Strength

Train each lift 2–3× per week

Frequency drives skill, and strength is a skill. Splitting your weekly volume across multiple sessions usually beats a single heavy day.

Spend most time at 70–85% 1RM

Working too heavy too often grinds joints and the nervous system. The sweet spot for long-term progress lives between 70% and 85% of your 1RM.

Peak with singles every 6–12 weeks

Doubling and singling at 90%+ for a few short weeks before a re-test lets you express the strength you have already built — without burning out year-round.

Eat at maintenance or a small surplus

Strength does technically build in a deficit, but slowly. A small surplus (+200–400 kcal) and 1.6–2.2 g protein per kg bodyweight is the simplest set-up for getting stronger.

Track your top set every session

Logging your heaviest set of the day in a notebook or app is the highest-leverage habit in lifting. You cannot beat what you do not measure.

Recover hard

Sleep at least seven hours, manage stress, and keep cardio low-intensity on heavy training days. Strength is built between sessions, not during them.

Common 1RM Mistakes

  • Estimating from a set taken to failure with sloppy form. Reps that lose tightness, depth, or bar path inflate the input and the estimated 1RM. Stop one or two reps short of failure and use that number instead.
  • Trusting a 12-rep set to predict a true single. Once you go above ~8 reps, the error band widens significantly. Re-test with a heavier 3–5 rep set for a meaningful 1RM number.
  • Updating the percentage base too often. Re-estimating every session creates noise. Most coaches recalculate every 4–8 weeks, or after a clear strength jump.
  • Testing on a bad day. Sleep, hydration, stress and even the time of day can swing a true 1RM by 5–10%. A single bad session does not redefine your max.
  • Ignoring exercise-specific norms. A 100 kg bench is impressive at 75 kg bodyweight and pedestrian at 110 kg. Strength is always relative — use the bodyweight ratio rather than the absolute number.

Disclaimer: This calculator provides estimated one-rep-max values for educational and training purposes only. It is not coaching or medical advice. Attempting a true 1RM carries real risk of injury — consult a qualified strength coach, especially if you are new to barbell training or have any existing joint, back or cardiovascular conditions.

Frequently Asked Questions

Your one rep max (1RM) is the heaviest weight you can lift for a single rep of a given exercise with full range of motion and good technique. It is the standard measure of pure strength used in powerlifting, weightlifting and most strength-and-conditioning programmes.

1RM calculators are accurate to within roughly ±5% of a true tested 1RM when you input a 1–6 rep set, and ±10% for 7–10 rep sets. They are far less reliable beyond 10 reps because muscular endurance and pacing dominate the result.

Epley is the most widely cited default and sits in the middle of the three. Brzycki is the most conservative, especially at higher reps. Lombardi behaves more smoothly across longer sets and is common in CrossFit programming. If you are unsure, run all three and treat the spread as a confidence band.

Not until you have at least 12 weeks of structured barbell training, clean technique in the lift you want to test, and ideally a competent training partner or spotter. Until then, estimating from a 3–5 rep set with this calculator is far safer and almost as informative.

Most lifters re-test or re-estimate every 6–12 weeks. Doing it more often creates noise; doing it less often makes your training percentages drift away from your real ability. Some powerlifting peaking blocks finish with a true 1RM attempt; most general programmes simply re-estimate.

A common rule of thumb for male intermediate lifters is bench at 1.0–1.25× bodyweight, squat at 1.5–1.75× bodyweight and deadlift at 2.0–2.25× bodyweight. For women the corresponding numbers are roughly 0.5–0.75× bodyweight bench, 1.0–1.25× squat and 1.25–1.5× deadlift. Use the bodyweight field above to see where your lift sits.

No — the 1RM estimate works from weight lifted and reps only. Bodyweight is only used to map your lift onto the strength-level scale (Beginner, Intermediate, Advanced, Elite). Leave it blank if you just want a number.

The 1RM equations themselves are gender-neutral — Epley, Brzycki and Lombardi work the same way for everyone. Sex only changes the strength-level thresholds because the reference standards used by Strength Level, ExRx and similar databases differ between male and female lifters.

Not directly. The equations assume you are lifting an external load. For weighted pull-ups, dips or chin-ups you can plug in (bodyweight + added weight) as the lifted weight to get a reasonable estimate. For pure bodyweight movements, use a dedicated rep-test calculator.

That spread is normal and is largest at higher rep counts. Each equation was fit to a different dataset, so they bracket the real value. If they disagree dramatically, your input set is probably above 8 reps — try estimating from a heavier, lower-rep set instead.

Spend most of your work between 65% and 85% of 1RM. Power and pure strength work happens in the 85–100% zone for low reps; hypertrophy in the 65–80% zone for 6–12 reps; endurance and conditioning below 65%. Cycle through these zones rather than living in any one of them.

It will still return a number, but the strength-level scale is calibrated on healthy adults. Older lifters and those returning from injury should rely on rep PRs at sub-maximal loads rather than chase a true 1RM, and always work with a qualified coach or physiotherapist if pain is involved.

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