Estimate your max from any set, then get your training weights by percentage and RPE.
Estimates from sets above 10 reps get unreliable. Use a heavier set if you can.
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Weight for each rep count and effort level.
If you only know the weight and reps, the calculator averages two well-known formulas:
Both assume the set was taken close to failure. If you stopped with several reps left, they'll underestimate your max.
If you rate the set's effort, the calculator uses the RPE chart popularized by Mike Tuchscherer of Reactive Training Systems (RTS). The chart's RPE 10 row gives the percentage of your max you can lift for a given number of all-out reps: 100% for 1, 95.5% for 2, 92.2% for 3, and so on. Lower RPEs mean reps in reserve, so 5 reps at RPE 8 is treated like 7 all-out reps (81.1%). Half steps are the average of their neighbors, which reproduces the published chart values.
The percentage table shows weights from 50% to 100% of your estimated max, with roughly how many reps you could do at each. The RPE chart turns that around: pick the reps and effort your program calls for (say, 3 reps at RPE 8) and read off the weight. Every weight is rounded to the plate increment you choose, so the numbers match what you can actually load.
Need help loading the bar? The plate calculator shows exactly which plates go on each side. Curious how your max compares with other lifters? Try How Strong Am I?
For sets of 1–5 reps, estimates are usually within a few percent of a true max. Accuracy drops as reps go up, because endurance varies a lot from person to person and lift to lift. Above about 10 reps, treat the number as a rough guide.
RPE (rate of perceived exertion) rates how hard a set was on a 1–10 scale, based on how many more reps you could have done: RPE 10 means nothing left, RPE 9 means one more rep, RPE 8 means two more. Adding RPE makes a 1RM estimate more accurate, because a set of 5 with two reps left is very different from a grinding set of 5.
They agree closely for low reps. Epley tends to estimate slightly higher and Brzycki slightly lower as reps increase, so this calculator averages the two. If you know your RPE, the RPE-based estimate is usually the better one.
No. Testing a true max is tiring and carries some risk. For most training, an estimated max from a recent heavy set is accurate enough to set your weights, and you can update it every few weeks from your logged sets.
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