RPE and RIR Explained: How Hard Should Each Set Be?

The RPE and RIR scale

The lifting version of RPE is anchored to reps left in the tank, which makes it more concrete than a general effort score. Half points, such as 8.5, mean you might have had one more rep, possibly two.

RPE 10 = 0 RIR: maximal. No more reps possible, and no extra weight.
RPE 9.5 = 0 RIR: no more reps, but slightly more weight might have been possible.
RPE 9 = 1 RIR: one more good rep was left.
RPE 8.5 = 1 to 2 RIR: one more rep for sure, maybe two.
RPE 8 = 2 RIR: two more good reps were left.
RPE 7 = 3 RIR: three more reps; the bar moves quickly.
RPE 5 to 6 = 4 to 6 RIR: moderate effort, like a heavier warm-up.
RPE 1 to 4: very light. Mostly warm-up and technique work.

Why use RPE or RIR at all?

Fixed percentages and fixed weights assume you are the same person every session. You are not. Poor sleep, stress, a busy week or a great day all change what you can lift. RPE lets the weight adjust to how you are performing today, while keeping the effort roughly where the programme intends.

It also helps control fatigue. Taking every set to failure is very tiring and can slow recovery. Stopping most sets one to three reps short of failure keeps most of the training benefit with less cost.

Finally, recording RPE makes your log more meaningful. A set of 5 at 100 kg at RPE 7 tells a very different story from the same set at RPE 10.

How to use it in your training

A programme might say 3 sets of 8 at RPE 8. You pick a weight you think you can lift for 8 reps with about 2 left. After the first set, rate it honestly. If it felt like RPE 6, add weight. If it felt like RPE 9.5, drop a little.

General guidance for common goals:

Main strength lifts: mostly RPE 7 to 9. Occasional RPE 9 to 10 for tests or top sets.
Muscle-building work: RPE 7 to 9, closer to 9 or 10 on safe isolation exercises.
Beginners and technique work: RPE 6 to 8, stopping well before form breaks down.
Deload or recovery weeks: RPE 5 to 7.

Getting better at judging effort

Most people, especially beginners, underestimate how many reps they have left. A set that feels like RPE 9 is often closer to RPE 7. That is normal and improves with practice.

To calibrate, occasionally take a safe exercise to true failure, such as a machine press, leg press or curl. Predict how many reps you will get before you start, then compare. Over a few weeks your predictions sharpen.

Do not test failure on exercises where failing is risky, such as barbell squats or bench press without safety bars or a spotter. On those, a cautious estimate is fine.

Bar speed is another clue. When reps slow down noticeably, you are usually within two or three reps of failure.

RPE and your one-rep max

RPE also lets you estimate your one-rep max without testing it. A set of 5 at RPE 8 is roughly equivalent to a set of 7 taken to failure, which you can plug into a 1RM formula. RepSensei's one-rep max calculator does this conversion for you, and the workout log can store RPE with each set so you can track trends.

Estimates are only as good as your RPE ratings, so treat them as a guide rather than an exact number.

Common mistakes

Letting ego set the number is the classic one: calling a grinding set RPE 8 so you can add weight next week. Be honest; the scale only helps if it is accurate.

Another is counting reps with poor form as reps in reserve. RIR means good, clean reps. If your technique would have fallen apart, those reps do not count.

Finally, do not chase RPE 10 to feel productive. Most good training is done at RPE 7 to 9.

How to log RPE

Rate the set straight after you finish, before you sit down, while the effort is fresh. Write it next to the weight and reps, for example 80 kg x 8 @ RPE 8.

You do not need to rate every warm-up. Rate your working sets, or at least the last set of each exercise, which is usually the hardest.

Over time, patterns appear. If the same weight and reps drop from RPE 9 to RPE 7 over a few weeks, you have got stronger, even if the bar has not moved yet. That is a cue to add weight.

Questions

What is the difference between RPE and percentage of 1RM?

Percentages fix the weight in advance from a tested or estimated max. RPE fixes the effort and lets the weight move with how you feel on the day. Many programmes use both: a percentage to start, then RPE to adjust.

What does RPE 8 mean?

A set where you could have done about two more good reps. It is a common target for working sets because it is challenging but leaves room for good form.

Is RIR the same as RPE?

They describe the same thing from opposite ends. RIR counts reps left; RPE rates effort on a 10-point scale. In lifting, RPE equals 10 minus RIR.

Should beginners use RPE?

Yes, loosely. Aim for sets that feel like RPE 6 to 8 and record a rating. Your judgement will improve with practice, and the habit is useful later.

Should I train to failure?

Occasionally, on safe exercises, it is fine and helps you calibrate. Most sets work well stopping one to three reps short of failure.

RPE and RIR Explained