RPE to Percentage Calculator

About the RPE to Percentage Calculator

RPE — rate of perceived exertion — is a way of measuring how hard a set was by the number of reps you had left. It has become standard in powerlifting and strength training because it adjusts to how you feel on the day: a set of 5 at RPE 8 is always hard but repeatable, whether you slept well or badly. But programmes and plate loading still need numbers, so lifters convert RPE into a percentage of one rep max and back again.

This RPE to percentage calculator converts reps at an RPE into a percentage of your one rep max and a working load, or works backwards from a set you have done to an estimated one rep max (e1RM). It uses the widely published RPE chart for 1 to 12 reps and RPE 6.5 to 10, and shows the percentages for other rep counts at the same RPE.

How to Use the RPE to Percentage Calculator

Choose Load from 1RM or Estimate 1RM from a set.

Enter your one rep max, or the weight lifted in the set.

Enter the number of reps, from 1 to 12.

Choose the RPE, from 6.5 to 10.

The Formula

RPE counts down from 10 in reps left in the tank — the reps in reserve (RIR):

  reps in reserve  = 10 − RPE
  effective reps   = reps + reps in reserve
  percentage       = chart value for the effective reps

  load             = one rep max × percentage
  estimated 1RM    = weight lifted ÷ percentage

Step-by-Step Examples

Load for 5 reps at RPE 8, with a 150 kg max.

  reps in reserve  10 − 8 = 2
  effective reps   5 + 2 = 7 reps to failure
  chart            81.1%
  load             150 × 0.811 = 121.7 kg

Estimated max from 100 kg × 5 at RPE 8.

  chart            81.1%
  estimated 1RM    100 ÷ 0.811 = 123.3 kg

Estimated max from 140 kg × 3 at RPE 8.5. Three reps with one or two left is 87.8 percent, so the estimate is 140 ÷ 0.878 = 159.5 kg.

The RPE Chart

Percentage of one rep max by reps and RPE:

  Reps   RPE 10   RPE 9   RPE 8   RPE 7
   1     100.0    95.5    92.2    89.2
   2      95.5    92.2    89.2    86.3
   3      92.2    89.2    86.3    83.7
   4      89.2    86.3    83.7    81.1
   5      86.3    83.7    81.1    78.6
   6      83.7    81.1    78.6    76.2
   8      78.6    76.2    73.9    70.7
  10      73.9    70.7    68.0    65.3
  12      68.0    65.3    62.6    59.9

Read along a diagonal and the same number repeats: 3 reps at RPE 9 and 4 reps at RPE 10 are both 89.2 percent. That is because both are as hard as 4 reps to failure. The whole chart comes down to one idea — reps done plus reps in reserve.

What the RPE Numbers Mean

  RPE 10    maximal — no more reps possible
  RPE 9.5   no more reps, but a little more weight might have gone up
  RPE 9     one rep left
  RPE 8.5   one rep left, maybe two
  RPE 8     two reps left
  RPE 7     three reps left
  RPE 6.5   three or four reps left

Below about RPE 6, lifters find it hard to judge reps in reserve accurately, which is why charts usually stop at 6.5.

Where the Chart Comes From

The chart most lifters use was popularised by powerlifting coach Mike Tuchscherer of Reactive Training Systems, who adapted the older Borg scale of exertion to strength training by tying it to reps in reserve. Research since has found that trained lifters judge reps in reserve reasonably well, especially close to failure, and less well on light sets or when new to the method. It is a practical tool built from experience, not a law of physiology, and it describes an average lifter.

Adjusting the Chart to You

Some lifters are "grinders" who can squeeze out many reps near their max; they will manage more reps at a given percentage than the chart predicts. Others are explosive and fatigue quickly, managing fewer. Lifts differ too: many people get more reps at a given percentage on the squat and bench than on the deadlift. Log your sets with their RPE, compare your estimated maxes over a few weeks, and adjust by a percent or two if you consistently sit above or below the chart.

Programming with RPE

Many modern strength programmes combine RPE with a top set and back-off sets. You work up to a single heavy set — say 3 reps at RPE 8 — and then drop the weight by a set percentage for the remaining sets. On a good day the top set is heavier; on a bad day it is lighter, and the whole session adjusts automatically. The chart gives you a sensible starting load: if your estimated max is 150 kg, 3 reps at RPE 8 suggests about 129.4 kg. If the set moves faster than expected, add a little weight for the next one; if it grinds, take some off. Over time your recorded sets also give you a running estimated max without ever testing a true single.

RPE and Reps in Reserve for Beginners

Judging reps in reserve takes practice. Newer lifters often stop sets they rate at RPE 7 when they could have done four or five more reps. A useful way to calibrate is to occasionally take a safe exercise, such as a machine or a set with safety bars, to true failure and compare it with what you predicted. Until your ratings are reliable, keep most sets at RPE 7 to 8 and use percentages as a cross-check.

Understanding Your Result

The headline is the percentage and load, or your estimated one rep max.

The percentage line restates the reps, RPE and chart value.

The reps in reserve line shows what the RPE means and the equivalent reps to failure.

The at this RPE line gives the percentage and load for other rep counts at the same RPE.

When Should You Use This Calculator?

Use it to choose a starting load for a set written as reps at an RPE.

Use it to estimate your max from everyday training without testing it.

Use it to track strength over time with an e1RM from your top sets.

Use it to convert between RPE-based and percentage-based programmes.

Common Mistakes

Overestimating reps in reserve. Most lifters underrate how close to failure they are on light sets.

Using the chart on very high reps. It stops at 12 reps for good reason.

Treating RPE 10 as a grind every time. Top sets at RPE 8 to 9 build most strength.

Ignoring your own pattern. Adjust the chart if your sets consistently differ.