Short answer: reps in reserve (RIR) is your estimate of how many more reps you could have done with good form when you stopped the set. RIR 0 means you could not do another. RIR 2 means about two more.
Reps in Reserve: A Simple Way to Record Set Difficulty
Workout Tracking · 26 October 2026
How it works
You finish a set and ask: "How many more clean reps did I have?" Write the number next to the set. In research and coaching, RIR is linked to a 1 to 10 effort scale where 10 equals 0 RIR and 9 equals 1 RIR (Zourdos et al., see sources).
Example
| Set | Weight | Reps | RIR |
|---|---|---|---|
| 1 | 60 kg | 8 | 3 |
| 2 | 60 kg | 8 | 2 |
| 3 | 60 kg | 7 | 0 |
The weight and reps look similar across sets, but the RIR shows the third set was a limit set.
How accurate is it?
Not perfectly. A scoping review and meta-analysis of rep-prediction accuracy found people tend to be more accurate the closer they are to failure, and less accurate when far away. Beginners often misjudge. Treat RIR as a useful estimate, not a measurement.
Tips for using it
- Start with the last set of each exercise. Do not rate every set at first.
- Use whole numbers. Do not split hairs.
- Be honest about form. A rep with broken form does not count.
- Compare over time. If the same load goes from RIR 1 to RIR 3, that suggests you got stronger.
- Be careful with heavy compound lifts. Stopping short of failure is usually safer on lifts like squats and bench presses without a spotter.
What RIR is not
It is not a guarantee of results, and it does not replace a programme. It is just a way to remember how hard a set felt. Whether your logging app has an RIR field or you write it in notes, the habit is the point.
A simple scale to start with
- RIR 4+: very easy, many reps left.
- RIR 3: comfortable.
- RIR 2: challenging but clean.
- RIR 1: very hard, one more rep with effort.
- RIR 0: failure, no more clean reps.
How to practise
Rate your sets after finishing, not during. Test your guess occasionally by safely taking a lighter set to failure on a machine or with a spotter and see how close you were. Over a few weeks your estimates tend to become more consistent.
Key takeaways
- RIR = reps left in the tank.
- Estimates improve closer to failure.
- Use it to compare effort, not to prove anything.
FAQ
Is RIR the same as RPE? They are related. In the commonly used RPE-RIR scale, RPE 10 is 0 RIR.
Should beginners use it? Yes, loosely. Expect rough guesses at first.
