Estimate your one-rep max from a hard set, compare common formulas, and get a usable training load table in pounds or kilograms.
How to use our One Rep Max Calculator
- Enter Weight lifted, choose Weight unit, and type the full Repetitions completed from one hard set done with good form.
- Pick an Estimation method. For most people, Consensus is the best starting choice because it compares several common formulas and uses the middle result.
- Choose a Training load table style and, if helpful, set Round loads to nearest so the table matches the plates or dumbbells you can actually load.
- Click Calculate, then read Estimated 1RM, Formula comparison, Formula spread, and the Percentage load table.
- Sanity-check the result: if Formula spread is large or the Rep-range note says your reps were high, treat the estimate as less certain and use the table as a starting point, not a guarantee.
Definitions
1RM: One-repetition maximum. The most weight you can lift one time with good form.
Estimated 1RM: A predicted 1RM based on your set, not a guaranteed max on that day.
Estimation method: The equation used to turn Weight lifted and Repetitions completed into an estimated 1RM.
Consensus: The median, or middle value, of the Epley, Brzycki, and Lander estimates.
Formula comparison: A side-by-side look at the three common 1RM estimates so you can see how closely they agree.
Formula spread: The difference between the highest and lowest formula result. Smaller spread means closer agreement.
Percentage load table: Suggested working weights at selected percentages of your estimated 1RM.
Round loads to nearest: A display setting that rounds table loads to a practical jump such as 5 lb or 2.5 kg.
Rep-range note: A short message about how your chosen rep count affects estimate reliability.
Common mistakes and quick fixes
Mistake: Entering body weight or total bar-plus-body system weight instead of the actual Weight lifted for the set.
Fix: Type only the load you actually lifted on the bar, machine, or dumbbell in Weight lifted .
Mistake: Mixing pounds and kilos by typing a kilogram number but leaving Weight unit on pounds.
Fix: Make sure Weight unit matches the number you entered before you calculate.
Mistake: Using partial reps, assisted reps, or a guessed count for Repetitions completed .
Fix: Enter only full, completed reps with good form in Repetitions completed .
Mistake: Treating one formula as exact and ignoring Formula comparison .
Fix: Check Formula comparison and Formula spread ; if the formulas are far apart, use the result more cautiously.
Mistake: Using very high reps and assuming Estimated 1RM is just as reliable as a lower-rep set.
Fix: Read the Rep-range note ; estimates are usually more stable when Repetitions completed is lower.
Mistake: Picking a percentage table but forgetting to set Round loads to nearest for real gym jumps.
Fix: Choose a useful Round loads to nearest value, or leave it at none if you want unrounded numbers in the Percentage load table .
Limitations & Key Assumptions / Boundary Conditions
- This tool estimates 1RM from a submaximal set. Real max strength can differ because of exercise choice, technique, fatigue, sleep, and motivation.
- Results are usually more trustworthy from lower rep sets. Higher-rep sets can make formulas disagree more and can reduce practical accuracy [1].
- The calculator accepts whole reps from 1 to 20 only. It does not model partial reps, forced reps, spotter help, or reps done with broken form.
- Estimated 1RM and the Percentage load table stay in the same unit as your selected Weight unit. No separate output-unit toggle is used.
- Round loads to nearest changes displayed training loads for convenience, but it does not change the underlying 1RM estimate.
- Prediction accuracy can vary across lifters and populations, including differences related to training status and sex [2].
- The table gives starting loads for programming. Actual working weight may need adjustment based on bar speed, range of motion, equipment, and how hard the set felt that day.
Methodology
How the calculator works
The tool uses your Weight lifted and Repetitions completed to estimate one-repetition maximum with common submaximal prediction equations. In Consensus mode, it calculates all three formulas and uses the median, which is the middle value after sorting the results.
Formulas used
1RM = w x (1 + r/30)
Epley formula, where w is lifted weight and r is completed reps.
1RM = w x 36 / (37 - r)
Brzycki formula.
1RM = 100 x w / (101.3 - 2.67123 x r)
Lander formula.
Primary 1RM in Consensus mode = median(Epley, Brzycki, Lander)
The median is used because it is less affected by one formula landing a little high or low.
Load at p% = primary 1RM x (p/100)
This creates each row in the Percentage load table.
Rounded display load = round(load/step) x step
If Round loads to nearest is set to none, the table shows unrounded values.
Worked mini-example
Suppose you lift 185 lb for 5 reps in one hard set.
Epley = 185 x (1 + 5/30) = 215.83 lb
Brzycki = 185 x 36 / (37 - 5) = 208.13 lb
Lander = 100 x 185 / (101.3 - 2.67123 x 5) = 216.15 lb
Sorted from low to high, the three estimates are 208.13, 215.83, and 216.15. The middle value is 215.83 lb, so that is the consensus estimate. A 75% training load would be 161.87 lb before any display rounding.
How to read the spread and rep note
Formula spread is the highest formula result minus the lowest formula result. A smaller spread means the formulas agree more closely. The Rep-range note gives a quick reliability reminder because lower-rep sets tend to support better prediction than higher-rep sets [1].
Assumptions used by the calculator
The calculator assumes your set was completed with consistent technique and honest full reps, that rep count is a whole number from 1 to 20, and that the selected equation is being used only as an estimate. Real testing conditions, exercise differences, and athlete population can change accuracy [1][2].