RPE and RIR explained: the scale, a chart and how to coach with them

What is the RPE scale, and what does RIR mean?

RPE (rating of perceived exertion) is a score of effort, and on the lifting scale it is tied to reps in reserve. The scale was published by Zourdos et al. (2016) and applied to training by Helms et al. (2016). RIR means the number of clean reps a lifter could still have done at the end of a set.

Source: Zourdos et al. (2016), as reprinted in Helms et al. (2016), Table 1.

What is RIR in bodybuilding and in the gym?

In bodybuilding and general gym use, RIR is the same thing: how far from failure a set ended. A set of 10 stopped with 2 reps left is "10 at 2 RIR". Coaches use it because muscle-building sets are usually taken close to failure, but not always to it, and RIR gives that distance a number.

Which RPE scale do you mean?

Three scales share the name, and mixing them up causes confusion:

• Lifting RPE (reps in reserve): 1 to 10, anchored to reps left. This is the scale in this post.
• Borg 6-20: a cardio scale where the number is meant to track heart rate.
• Borg CR10: a 0 to 10 scale of breathlessness or effort, mostly used for cardio and clinical settings.

For cardio intensity, a coach would pair effort ratings with heart rate zones; the heart rate zone calculator covers that side.

What is the difference between RPE and RIR?

RPE and RIR describe the same set from two directions: RPE scores effort from 1 to 10, while RIR counts reps left. From RPE 7 upward on the lifting scale, RPE equals 10 minus RIR. RPE 8 and 2 RIR are the same set.

• Use RIR when the client is new to this. "How many more could you have done?" is a concrete question.
• Use RPE when you want one number that also allows half points, such as 8.5, for a set between 1 and 2 reps left.
• Write both if clients get confused: "RPE 8 (2 left)".

One caution: the published scale has no half points. The chart used in many tools places them halfway between whole numbers, which is a convention rather than a measured value.

How do I know my RIR?

A lifter knows their RIR by finishing a set and asking how many more good reps were possible, counting only reps with normal technique. Rate it straight afterwards, while the set is fresh. Here is a simple routine to teach a client:

1. Do the set and stop when you choose, not when the bar stops.
2. Ask: "How many more clean reps could I have done?" None is RPE 10, one is RPE 9, two is RPE 8, three is RPE 7.
3. Write the number next to the weight and reps.
4. Occasionally check it: rate a set, rest, then repeat the same load to failure. The gap shows whether the rating was honest.

How accurate is RPE?

Accuracy depends on experience and on how close to failure the set ends. In the 2016 study, experienced squatters rated a true maximum at 9.8 on average and novices at 9.0. A 2022 scoping review and meta-analysis by Halperin et al. of 12 studies and 414 people found that predictions of reps left improved closer to failure and with heavier loads. People tend to underestimate how many reps remain, by about one.

For coaches, this means:

• Beginners can rate sets from day one, but should not rely on RPE alone to set loads until their ratings match reality.
• Sets ending 4 or more reps from failure are hard to judge. Use a range, such as "4–6 left".
• Treat RPE as a tool to adjust a plan, alongside logged numbers and technique.

What does an RPE chart say about percentage of 1RM?

An RPE chart gives the share of a one-rep max (1RM) that a given number of reps at a given RPE represents. The table below is a section of Table 2 from Helms et al. (2016), which is based on experienced lifters' back squats in Zourdos et al. (2016).

The value depends only on reps plus reps in reserve. Five reps at RPE 8 and 7 reps at RPE 10 are both 81%, because both end seven reps from failure. The full grid, from 1 to 8 reps and RPE 7 to 10, with half points, is in the RPE chart and calculator.

Where the chart stops working

The table covers 1 to 8 reps and RPE 7 to 10 only. It was built from mean values in experienced lifters doing the back squat, and the authors warn the relationship may differ for machines, single-joint and upper-body exercises. Individuals vary too: at 8 reps with 70% of 1RM, about two-thirds of lifters would report 2 to 4 reps left, and some as few as 1 or as many as 5. Use the chart to pick a first load, then adjust from what the client logs.

Example: set a load from RPE and estimate a 1RM

The numbers below are illustrative. A client squats 100 kg for 5 reps and rates it RPE 8 (2 reps left).

1. Find the percentage. 5 reps at RPE 8 is 81% in the chart.
2. Estimate the 1RM. 100 ÷ 0.81 = about 123.5 kg.
3. Plan a heavier set. For 3 reps at RPE 9 the chart gives 87%. 123.5 × 0.87 = 107.4 kg, rounded to 107.5 kg.
4. Plan a lighter volume set. For 8 reps at RPE 7 the chart gives 70%. 123.5 × 0.70 = 86.4 kg, rounded to 86.5 kg.

The same maths works in pounds. If you only have a rep max from a test, the one-rep max calculator estimates a 1RM from other rep ranges, and the result feeds step 2 in the same way. Round loads to the plates the client actually has.

How do you coach clients with RPE?

A coach prescribes a rep target and an RPE, and lets the client choose the load that lands there on the day. "3 sets of 5 at RPE 8" is a complete instruction. Helms and colleagues suggest 6 to 12 reps at RPE 8 to 10 for muscle growth, with main lifts such as squats kept mostly at RPE 6 to 8.

A simple weekly pattern

• Teach first. In week one, have the client rate every set and write the number down. Do not change loads on RPE yet.
• Prescribe a range. Give a target such as RPE 7 to 8 on main lifts, so small misjudgements do not matter.
• Mix with percentages. Use a percentage for the plan and a reps-in-reserve target to adjust it on the day, for example 3 sets of 3 at a set percentage with "0 to 1 reps in reserve".
• Keep failure rare. Take RPE 10 mostly on the last set of simpler exercises, because failure can cut the reps managed afterwards.
• Review the numbers. If a client's RPE keeps rising at the same load, ask about sleep, stress and food before changing the programme.

When to hold back

This is general education for coaches, not medical advice. Refer clients with pain, an injury, a medical condition or a pregnancy to a doctor before training close to failure. Clients with a history of disordered eating need a registered dietitian and a doctor involved, not just a rating scale.

FAQs