RPE vs RIR: How to Rate and Use Lifting Effort

In strength training, RPE and RIR describe the same thing from two directions. RIR (reps in reserve) is how many more good reps you could have done when you racked the bar, and RPE (rating of perceived exertion) is 10 minus that number, so RPE 10 = 0 RIR, RPE 9 = 1 RIR, and RPE 8 = 2 RIR. Use whichever word your program uses, rate every working set honestly, and you have a simple way to adjust loads to the day you are actually having.

The RPE scale for lifting

The table below is the scale most lifting programs use. Half points let you split the difference when you are unsure, for example when you might have squeezed out one more rep.

RPE	RIR	What it means
10	0	Maximal. No more reps possible, and no more load either
9.5	0-1	No more reps, but maybe a little more load
9	1	One more rep was there
8.5	1-2	Definitely one more, maybe two
8	2	Two more reps
7.5	2-3	Two more, maybe three
7	3	Three more reps; bar speed is still quick
5-6	4-6	Warm-up or light technique work

Below about RPE 6, ratings get vague and are not very useful for working sets. Most strength work lives between RPE 6 and 9. You can keep a printable copy of this scale with the RPE chart tool.

Where the two scales came from

The original RPE scale has nothing to do with reps. Gunnar Borg developed category scales for rating overall effort during whole-body exercise such as cycling, including the familiar 6-20 scale and later a 0-10 category-ratio scale (Borg, 1982). Those scales ask “how hard does this feel?”, which works for steady cardio but is fuzzy for a heavy set of three.

Resistance-training researchers anchored the 1-10 scale to something concrete: reps left before failure. Zourdos et al. (2016) tested this RIR-based RPE scale in squatters and found that ratings tracked bar velocity and load, with experienced lifters rating more consistently than novices. Helms et al. (2016) then laid out how coaches can program with it, including using RPE targets to set loads and autoregulate from set to set.

So when a lifting program says “RPE,” it almost always means the RIR-based version, not Borg’s original. The scale used here is that RIR-based version.

How accurate are RPE ratings?

Not perfectly accurate, and that is fine as long as you know the pattern:

Closer to failure is more accurate. Predictions made near the end of a hard set are better than predictions made on light sets with many reps left (Halperin et al., 2022).
People tend to underestimate what they have left. The same meta-analysis found lifters underpredicted reps to failure by roughly one rep on average, with wide variation between individuals.
Experience helps, but does not fix it. Steele et al. (2017) found trained lifters predicted better than untrained ones, though nobody was perfect.
Lower-rep sets are easier to rate. Accuracy was better on sets of 12 reps or fewer than on long, high-rep sets (Halperin et al., 2022).

In practice, this means an RPE 8 from a newer lifter might really be RPE 6.5. One way to calibrate is to occasionally take a final set of an exercise to a true RPE 10 (on a safe exercise, with safeties or a spotter) and compare how many reps you actually got with what you predicted.

How to log RPE

Rate each working set right after you rack the bar, before you rest. Write it next to the set, not at the end of the session when everything blurs together. A clean format is load x reps @ RPE:

Squat
100 kg x 5 @ 7
100 kg x 5 @ 7.5
100 kg x 5 @ 8

Three things make the ratings more useful later:

Rate only the set you just did. Don’t adjust it because the previous set felt easier.
Rate rep quality, not grind. If form broke down on the last rep, the set was closer to failure than it felt.
Keep the same format every session so you can compare week to week.

The lifting log generator builds sheets with a column for RPE on each set, so the rating has a place to go. For more on what to record, see how to use a lifting log.

Using RPE targets to pick loads

An RPE target turns “do 5 reps” into “do 5 reps with about 2 left.” Here is a simple way to run it:

Start from a planned load. Use your recent best set or an estimated 1RM to pick a reasonable starting weight.
Do the first working set and rate it.
Adjust the next set. If the target is RPE 8 and you rated 7, add a small jump (about 2.5-5%). If you rated 9, drop by a similar amount.
Stop adjusting once you are in range. Half a point either side is close enough.

For example, the plan is squat 3 x 5 @ 8. Your first set at 120 kg (265 lb) feels like RPE 7. You go to 125 kg (275 lb) and rate it 8. You stay there for the remaining sets. On a bad sleep day the same 120 kg might feel like RPE 8.5, and you would hold or drop the load instead.

This kind of autoregulation works. In a study comparing RPE-based and percentage-based loading with matched sets and reps, both groups got stronger, and RPE-based loading showed a small strength advantage in a majority of participants (Helms et al., 2018).

RPE and %1RM: a useful approximation

Because reps done plus reps in reserve roughly equals the reps you could do to failure, you can link RPE to a percentage of your one-rep max. A set of 5 at RPE 8 behaves like a 7-rep max. The figures below are typical values from commonly used charts, rounded:

Reps	RPE 10	RPE 9	RPE 8	RPE 7
1	100%	96%	92%	89%
3	92%	89%	86%	84%
5	86%	84%	81%	79%
8	79%	76%	74%	71%

Treat these as a starting point, not a law. Rep-max relationships vary by lift and by person, and your RPE ratings carry their own error. Plug a recent set into the one-rep max calculator to get an e1RM, then use the table to pick loads. The 1RM formulas guide explains why different formulas give different numbers.

Common mistakes

Mixing up the scales. Borg’s scale rates overall effort. Lifting RPE rates reps left. Don’t log “RPE 15” on a bench set.
Rating everything 8. If every set is an 8, the number is not telling you anything. Use the full range.
Ignoring rep speed. A rep that slows sharply is a sign you are close to failure, even if it felt fine.
Chasing the number instead of the target. If the plan says RPE 7, stopping at 7 is the point. Going to 9 because you feel good adds fatigue you will pay for later.
Trusting a single set. One RPE rating is noisy. Trends across weeks are what matter.

Questions lifters ask

Is RPE 8 the same as 2 RIR?

Yes. On the resistance-training RPE scale, RPE is 10 minus the reps you had left, so RPE 8 means you could have done about 2 more reps with good form.

Are beginners accurate at rating RPE?

Less accurate than experienced lifters, especially on sets that end far from failure. Accuracy tends to improve with practice and when sets are closer to failure, so beginners should treat RPE as a rough guide at first.

Can I use RPE to estimate my 1RM?

Yes, as an approximation. A set of 5 at RPE 8 is treated like a 7-rep max effort, which you can plug into a 1RM formula. The estimate is only as good as your rating.

Sources

Borg GA. Psychophysical bases of perceived exertion . Medicine & Science in Sports & Exercise, 1982;14(5):377-381
Zourdos MC, Klemp A, Dolan C, Quiles JM, Schau KA, Jo E, Helms E, Esgro B, Duncan S, Garcia Merino S, Blanco R. Novel Resistance Training-Specific Rating of Perceived Exertion Scale Measuring Repetitions in Reserve . Journal of Strength and Conditioning Research, 2016;30(1):267-275
Helms ER, Cronin J, Storey A, Zourdos MC. Application of the Repetitions in Reserve-Based Rating of Perceived Exertion Scale for Resistance Training . Strength and Conditioning Journal, 2016;38(4):42-49
Steele J, Endres A, Fisher J, Gentil P, Giessing J. Ability to predict repetitions to momentary failure is not perfectly accurate, though improves with resistance training experience . PeerJ, 2017;5:e4105
Halperin I, Malleron T, Har-Nir I, Androulakis-Korakakis P, Wolf M, Fisher J, Steele J. Accuracy in Predicting Repetitions to Task Failure in Resistance Exercise: A Scoping Review and Exploratory Meta-analysis . Sports Medicine, 2022;52(2):377-390
Helms ER, Byrnes RK, Cooke DM, Haischer MH, Carzoli JP, Johnson TK, Cross MR, Cronin JB, Storey AG, Zourdos MC. RPE vs. Percentage 1RM Loading in Periodized Programs Matched for Sets and Repetitions . Frontiers in Physiology, 2018;9:247

This guide is general education about training, not medical advice. If something hurts, stop and get it checked by a qualified professional.