RPE in strength training: how hard was that set?

What does RPE mean?

RPE stands for Rating of Perceived Exertion. In strength training, it describes how much you had left at the end of a set. At RPE 8, you could have done roughly two more repetitions; at RPE 9, one more. RPE 10 means another repetition with the same technique was beyond you.

Those remaining repetitions are called RIR, or Reps in Reserve. A target of 2 RIR means stopping about two repetitions before your limit. RPE 8 describes the same distance. You do not have to train to failure first; estimate what was left when you finish the set.

Rate the set immediately after its last repetition. Ask how many more repetitions you could have completed with the same technique.

RPE 6 to 10 as a practical RIR scale

The mapping estimates how many technically comparable repetitions you had left. Reserve is harder to judge in easy sets, so lower RPE values tend to be less precise.

• RPE 10: no additional technically comparable repetition in reserve
• RPE 9: approximately one repetition in reserve
• RPE 8: approximately two repetitions in reserve
• RPE 7: approximately three repetitions in reserve
• RPE 6: approximately four repetitions in reserve; clearly submaximal
• RPE 5 or below: easy work, warm-up work, or a set with substantial reserve

Technically comparable matters: a forced repetition with a major technique change is not simply another repetition in reserve.

Target RPE 8: three outcomes and what to do next

Suppose you plan 8 repetitions at RPE 8. The plan gives you a target. Your log records the effort you actually experienced.

Rate the set, not the whole workout

Breathing hard after squats or feeling a burn during lateral raises can be uncomfortable. For this RPE scale, judge how many further repetitions you could perform with the same technique. You can record general tiredness separately; it does not replace the set rating.

Estimate your reserve immediately after the set, before checking the target in your plan. “About two or three repetitions left” is a useful starting point. Practise with familiar exercises and similar repetition counts to develop a better sense of your reserve.

If a target-RPE-8 set was actually RPE 10, check your rest first. Then choose a lighter available weight when that will help you regain the planned reserve. The size of that step depends on the exercise, repetition count and weights available.

RPE and RIR: two views of the same set

RIR counts the repetitions you estimate were left, while RPE expresses that effort on an ascending scale. In the common RIR-based reading, the two roughly translate: 2 RIR is about RPE 8, and 1 RIR about RPE 9.

Accuracy depends on the set. A study in trained participants found better RIR estimates closer to failure and at low to moderate repetition counts. In a long, easy set, estimating reserve to the nearest repetition is harder.

Record RPE while the set is fresh

Put the weight down and take a moment to think about how many more repetitions you could have done. “Two, perhaps three” is a useful starting estimate. Record it alongside weight and repetitions. After several sets, the memory gets blurry, especially if the last round was much harder.

Familiar exercises help you learn the feeling. Compare the first and last sets of a row: the same load and technique, but less left at the end. That is the difference your RPE should capture.

• Record RPE immediately after the set
• Keep technique and range-of-motion standards consistent
• Log weight, repetitions, and RPE together
• Rate the set you performed, not the target printed in the plan

Five common RPE mistakes

RPE stops being useful when the number only confirms what the plan was supposed to say. A prescribed RPE-8 set does not remain RPE 8 through wishful thinking when the final repetition is unexpectedly slow or technically compromised.

• Calling every uncomfortable set RPE 10
• Treating muscle burn or general fatigue as the same thing as RPE
• Comparing sets performed to different technique standards
• Reading one RPE deviation as proof that performance is lost
• Treating a subjective estimate like an exact laboratory value

What several sessions can tell you

Last time, eight repetitions at 60 kg felt very hard. Today, the same eight leave something in reserve. The weight and repetition count look identical in your log, but the lower RPE shows the extra room. That can be progress before you add another plate.

LiftPal keeps RPE beside weight and repetitions, so you return knowing both what you did and how hard it felt. One tough day need not change your plan. If the same load keeps feeling much harder, look at rest between sets, sleep and the amount of training you are doing.

When judging your reserve is difficult

With a new exercise, you may not yet know what your limit feels like. Start with a weight you control comfortably and learn the movement. Even experienced lifters can struggle to tell whether six or ten repetitions remain in a long, light set. A broad estimate is more useful here than a decimal point.

Use the same technique each time: an extra repetition with a much shorter range changes the task. Stop if you feel pain or dizziness. Those symptoms need attention beyond giving the set a higher RPE.

Plan the next set with your own numbers

Enter your last working sets, repetition range and reserve in the progression planner. See whether your chosen rule points toward more repetitions, the same weight or a small load increase.

Find the decision again at your next workout

LiftPal’s free log stores weight, repetitions and RPE for each set. Your history shows what worked last time. You can accept or decline coaching suggestions during a workout. Premium adds editable training blocks and deeper coaching reviews.