Glossary
Reps in Reserve (RIR)
Written by the GymStreak coaching teamUpdated
Definition
Reps in reserve (RIR) is the number of extra good reps you could have done when you ended a set. 0 RIR means you reached failure; 2 RIR means you stopped with about two reps left.
01 / RIR chart
RIR chart (and how it matches RPE)
RIR is the basis of the lifting RPE scale, so the two convert directly: take the RIR away from 10 to get the RPE.
| RPE | Reps in reserve | What it feels like |
|---|---|---|
| 10 | 0 | Maximal effort: no more reps possible |
| 9.5 | 0 | No more reps, but you could have used slightly more weight |
| 9 | 1 | One more rep possible |
| 8.5 | 1–2 | One, maybe two more reps |
| 8 | 2 | Two more reps possible |
| 7.5 | 2–3 | Two, maybe three more reps |
| 7 | 3 | Three more reps possible |
| 5–6 | 4–6 | Moderate effort |
| 3–4 | — | Light effort |
| 1–2 | — | Little to no effort |
02 / How many
How many reps in reserve should you leave?
- For most working sets, 1–3 RIR. A 2023 meta-analysis found only a trivial difference in muscle growth between sets taken to failure and sets stopped short of it, and a 2024 meta-regression found strength gains were similar across a wide range of RIR.
- For muscle growth, closer is a little better. The same 2024 analysis found muscle growth increased as sets ended closer to failure, so 0–2 RIR on the last set of an exercise is reasonable if your form holds.
- Beginners: 2–3 RIR while learning a lift. Technique matters more than squeezing out the last rep.
- Keep more in reserve on heavy, complex lifts (squats, deadlifts, bench press without a spotter) and less on machines and small isolation exercises, where a missed rep is safe.
03 / Estimating
How to estimate your RIR
- Ask straight after the set: “With the same form, how many more could I have done?” Round to the nearest whole rep.
- Expect to guess low at first. A 2017 study found most trainees underpredict how many reps they have left, and get more accurate with experience.
- Calibrate now and then: on a safe exercise (a machine, or a set with a spotter), keep going to the last good rep and compare that with your guess.
- Your speed is a clue: when reps slow down sharply, you are usually within 1–3 reps of failure.
04 / FAQ
Frequently asked questions
What does 2 RIR mean?
2 RIR means you stopped the set when you could still have done about two more good reps. It is the same as RPE 8.
Is training to failure better than leaving reps in reserve?
Not by much. A 2023 meta-analysis found only a trivial advantage for failure training on muscle growth, and failure sets cost more fatigue. Most sets at 1–3 RIR, with the occasional set closer to failure on safe exercises, is a practical middle ground. More in our post on training to failure.
How many reps in reserve for strength?
Strength gains seem similar across a wide range of RIR, so heavy strength work is usually done at 1–3 RIR, leaving more in reserve on the heaviest, most technical lifts.
What is the difference between RIR and RPE?
RIR counts the reps you had left; RPE rates the effort on a 1–10 scale. On the lifting scale, RPE = 10 − RIR. See RPE.
Sources
- Zourdos MC, Klemp A, Dolan C, et al. Novel resistance training-specific rating of perceived exertion scale measuring repetitions in reserve. J Strength Cond Res. 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 Cond J. 2016;38(4):42-49.
- Refalo MC, Helms ER, Trexler ET, Hamilton DL, Fyfe JJ. Influence of resistance training proximity-to-failure on skeletal muscle hypertrophy: a systematic review with meta-analysis. Sports Med. 2023;53(3):649-665.
- Robinson ZP, Pelland JC, Remmert JF, et al. Exploring the dose-response relationship between estimated resistance training proximity to failure, strength gain, and muscle hypertrophy: a series of meta-regressions. Sports Med. 2024;54(9):2209-2231.
- 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.
Put it into practice
- Workout plan3-Day Full Body Workout PlanTwo alternating full body sessions, three days a week. The best all-round starting plan.
- Workout planBeginner Gym Workout PlanYour first 8–12 weeks in the gym: 3 short full body days with machines and dumbbells.
- Workout planNo-Equipment Home Workout PlanTwo full body bodyweight workouts, 3 days a week. Only a chair and some floor space.
Related terms
Read more
- Should You Be Training to Failure? (New 2024 Research)We last talked about training to failure in 2019. It's now 2024! Five whole years have passed — what's new? Has our stance changed? Answers here.5 min read
- How To Prevent Excessive Fatigue After TrainingFatigue after training: too much is not good, but neither is too little. So, how do you straddle the thin line and achieve optimal muscle growth?6 min read
- Maximizing Muscle Growth: How Hard Should You Be Training?How hard should you be training – really, for optimal muscle growth? Get the answer in this article, plus understand the signs of overtraining.5 min read
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