Estimate your one rep max (1RM) from a submaximal set using the Epley, Brzycki, and Lombardi formulas — plus a training percentage table for programming your next cycle.
Training Percentage Chart:
| % of 1RM | Weight | Typical Reps |
|---|
Enter Your Lift
Enter the weight and reps from a recent set to estimate your one rep max
The one rep max calculator (1RM calculator) estimates the heaviest weight you could lift for a single, complete repetition, based on a lighter set you've already performed. Instead of risking injury by attempting an actual maximal lift, you plug in the weight and reps from a recent working set — for bench press, squat, deadlift, or any barbell movement — and this free 1RM calculator returns a strength estimate using three widely cited formulas: Epley, Brzycki, and Lombardi, calculated side by side along with their average.
A one rep max is the maximum load you can move for one full repetition with proper form. Testing it directly is demanding on the joints and nervous system, so strength coaches and researchers developed prediction formulas that estimate 1RM from a submaximal set — a set performed with less weight for more than one rep. This calculator applies three of the most established formulas to the weight and reps you enter, then reports each estimate individually plus a combined average, giving you a range rather than a single guess.
This 1RM calculator is built for recreational and competitive lifters, powerlifters, strength athletes, CrossFit and functional-fitness participants, and personal trainers who need a fast, evidence-based strength benchmark without a maximal test. It's especially useful for anyone programming percentage-based training, such as 5/3/1, linear periodization, or block programming, where working weights are prescribed as a percentage of 1RM rather than a fixed number.
Knowing your estimated max lift lets you program training percentages accurately and track strength progress objectively over time. The training percentage chart below converts your estimated max into practical working weights across the 50-95% intensity range, each paired with a typical rep count you'd expect to hit at that load — turning a single number into a full week of programmable training weights.
How this one rep max calculator converts weight and reps into a strength estimate
All three formulas take the same two inputs — the weight you lifted and the number of reps you completed — and are calculated simultaneously by this calculator. You select which one is featured as your headline estimate, but every result panel also shows Epley, Brzycki, Lombardi, and their average side by side.
One of the most widely used 1RM formulas, popular for its simplicity. It applies a linear adjustment based on reps and tends to run slightly higher than Brzycki at higher rep counts.
Often favored for lower rep ranges (under 10). Its denominator (37 − Reps) shrinks as reps rise toward 37, which can understate 1RM for higher-rep sets and becomes undefined at exactly 37 reps.
Uses a power function of reps (Reps^0.10) rather than a linear or fractional adjustment. Estimates typically land between Epley and Brzycki across most common rep ranges.
From your last training set to a full training percentage chart
Use a set of 2-10 reps taken close to (but not at) technical failure on the lift you want to estimate, such as bench press, squat, or deadlift.
Type the weight you used for that set, in kilograms, into the Weight Lifted field.
Type how many clean, full-range reps you completed with that weight, between 2 and 15.
Pick Epley, Brzycki, or Lombardi as your headline estimate — all three are calculated and compared regardless of which you choose.
See your estimated one rep max, a side-by-side comparison of all three formulas and their average, and a training percentage chart from 50% to 95% of your estimated max.
Using the calculator's own default scenario — 100 kg for 5 reps, Epley formula
Suppose you lifted 100 kg for 5 reps on your last working set, and you leave the formula selector on its default, Epley.
Explanation: All three formulas land within about 5 kg of each other (112.5-117.5 kg) for this rep range, which is typical agreement for a 5-rep submaximal set. The Epley estimate of 116.7 kg becomes the calculator's headline number since Epley is the default selection, but the average of 115.5 kg is a reasonable, balanced figure to program from if you'd rather not favor any single formula.
How rep range affects the reliability of your estimate
| Reps Performed | Estimate Reliability | What It Means |
|---|---|---|
| 2 – 3 reps | Very high | Closest to an actual maximal lift; formulas agree closely and the estimate is the most trustworthy |
| 4 – 8 reps | High | The most commonly recommended range for this calculator; formulas typically agree within a few percent |
| 9 – 12 reps | Moderate | Formulas begin to diverge more; the average of all three becomes more useful than any single formula |
| 13 – 15 reps | Lower | Muscular endurance starts influencing the result as much as raw strength; treat the estimate as a rough guide |
| 16+ reps | Not supported | This calculator caps reps at 15 because formulas become unreliable beyond that point |
If your reps were in the 2-8 range: your estimate is likely within about 5-10% of your true 1RM, assuming the set was taken close to failure with good form.
If your reps were in the 9-15 range: lean on the average-of-three figure rather than a single formula, and consider re-testing with a heavier weight for fewer reps if you want a tighter estimate.
This result is for informational purposes only and is not a medical diagnosis. A 1RM estimate is a strength-programming tool, not a certified test result — it does not know your training history, joint health, or technique quality on the specific lift.
This calculator provides educational estimates only and should not be used as a substitute for professional medical advice, diagnosis, or treatment. Results may vary depending on individual health conditions. Always consult a qualified healthcare professional regarding medical concerns.
Safety note: Attempting an actual true one-rep max lift carries real injury risk — it pushes joints, connective tissue, and the nervous system to their limit. If you ever do test a true 1RM, use a proper progressive warm-up, have a qualified spotter present for exercises like bench press and squat, prioritize strict form over the number on the bar, and stop the attempt if your form breaks down. This calculator exists specifically so you can estimate your max without taking on that risk.
Where a fast, formula-based strength estimate is genuinely useful
Use your estimated 1RM as the training max that percentage-based programs build their weekly loads from.
Get a percentage-ready number without the fatigue and joint stress of an actual max attempt.
Recalculate from a similar submaximal set periodically to see whether your estimated max is trending up.
Use a recent training estimate to sanity-check planned opener, second, and third attempts.
Bodybuilding-style blocks often prescribe 65-75% of 1RM for higher-volume, muscle-growth-focused work.
Estimate strength changes from safer submaximal sets instead of testing a true 1RM every few weeks.
Calculate independent 1RM estimates for bench press, squat, and deadlift to compare relative strength.
Trainers can estimate a new client's strength baseline without a risky maximal-lift test on day one.
Estimate 1RMs for barbell lifts commonly programmed as percentage-based strength work in WODs.
Re-establish an approximate max after a training break, injury layoff, or long travel period.
Use your estimated max as a reference point when comparing your strength to published strength standards.
Use the training percentage chart to plan a progressive warm-up leading into a heavy top set.
Compare a calculated 1RM against your subjective RPE (rate of perceived exertion) estimates for consistency.
Sum estimated bench, squat, and deadlift maxes for a rough powerlifting total before a meet.
Coaches and students can use it to illustrate how different 1RM prediction formulas compare in practice.
What this one rep max calculator does well, and where it can't replace a supervised test
How the three 1RM formulas this calculator uses compare
| Formula | Equation | Best Rep Range | Typical Tendency |
|---|---|---|---|
| Epley | 1RM = W × (1 + R ÷ 30) | 2 – 10 reps | Runs slightly higher, especially at higher rep counts |
| Brzycki | 1RM = W × 36 ÷ (37 − R) | 2 – 10 reps | Can understate 1RM at higher reps; undefined at 37 reps |
| Lombardi | 1RM = W × R0.10 | 2 – 12 reps | Sits between Epley and Brzycki for most rep counts |
| Average of Three | (Epley + Brzycki + Lombardi) ÷ 3 | 2 – 15 reps | A balanced, formula-agnostic consensus estimate |
Summary: This one rep max calculator gives you an instant, free 1RM estimate using the Epley, Brzycki, and Lombardi formulas side by side, plus a training percentage chart you can program straight from — a useful strength benchmark, not a certified test result. Pair it with related tools like the TDEE Calculator and Target Heart Rate Calculator for a fuller picture of your training and recovery needs.
Common questions about one rep max calculations
Official guidance to complement this calculator — not a substitute for licensed medical or coaching advice
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