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Reps From Percentage Calculator

See the load and rep count for any percentage of your one-rep max.

How it is calculated

Enter your one-rep max M and a training percentage p of it (30 to 100). The tool returns two numbers. The working weight is W = M × p / 100, shown to two decimals in the same unit as your max. The estimated number of reps you could do with it comes from solving the Epley formula for reps: reps = 30 × (100/p − 1), rounded to the nearest whole number and never below 1. It gives a single estimate, not a range, and uses only Epley, not Prilepin's table or Brzycki. Percentages under 30 or above 100 give no result. At light percentages the rep figure climbs fast (30 % gives 70), far beyond what the formula was built for, so trust it mostly between 60 % and 100 %.

Worked example

Your one-rep max is 140 and the plan says 85 %. Working weight: 140 × 85 / 100 = 119, shown as 119.00. Estimated reps: 30 × (100/85 − 1) = 30 × 0.1765 = 5.29, rounded to 5. So the tool shows a training weight of 119.00 and about 5 reps to failure. At 80 % the same max would give 112.00 for 8 reps (7.5 rounds up), and at 100 % it gives 140.00 for 1 rep.

Try this example →

Common mistakes

  • Typing the percentage as a decimal, such as 0.85. The field expects 85; values under 30 return no result.
  • Reading the rep figure as the reps to program. It is the estimated maximum number of reps to failure at that load, so a prescription of 5 reps at 85 % is usually far from failure.
  • Using a 1RM that was itself estimated from a high-rep set. Errors compound, so the weight and the rep estimate drift from reality.
  • Expecting the same reps for every lifter and every lift. The formula is an average; many people get fewer reps on deadlifts than on leg press at the same percentage.
  • Trusting very low percentages. At 30 to 50 % the formula suggests dozens of reps, which is outside the range where it is reliable.

Sources

About this calculator

In strength training, your one-rep max (1RM) is the heaviest weight you can lift for a single complete repetition, and training programs are commonly prescribed as a percentage of that number — "work up to 5 reps at 80% of your 1RM," for example. Because the relationship between load and maximum achievable reps is well documented (heavier percentages allow fewer reps, lighter percentages allow more), tables like Prilepin's chart or the Epley/Brzycki rep-max formulas let you estimate roughly how many reps a given percentage should allow before failure.

Powerlifters, Olympic weightlifters and strength coaches use percentage-based programming because it scales automatically to each athlete's current strength level and removes guesswork from periodization — a coach can prescribe "70% for 8 reps" once and have it apply correctly to every lifter on the team, regardless of their individual 1RM. It's also how lifters plan deload weeks (lower percentages, same or fewer reps) and peaking blocks leading into a competition (rising percentages, dropping rep counts).

This calculator takes your 1RM and a target percentage and returns the corresponding training weight along with a single estimated rep count, calculated with the Epley formula and rounded to a whole number. It is a single estimate rather than a range, and it accepts percentages from 30% to 100%.

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