RPE and RIR Explained: Training by Feel
Your program says to do 3 sets of 8 reps. But if those 8 reps are too easy you are not stimulating much growth; too hard and you are accumulating unnecessary fatigue. RPE and RIR give you a language for how close to your limit each set actually is.
What RPE and RIR mean
RPE stands for Rate of Perceived Exertion. On a 1-10 scale, RPE 10 is absolute failure (no more reps possible), RPE 9 means one rep left in reserve, RPE 8 means two reps left, and so on. RIR, Reps in Reserve, is the exact count the scale is anchored to. They are two ways to describe the same thing: RPE 8 equals 2 RIR, RPE 7 equals 3 RIR.
Why it matters more than chasing a fixed weight
A fixed weight is a fixed weight, but your capacity varies day to day. Sleep, stress, food timing and cumulative fatigue all shift how a given weight feels. RPE-guided training keeps the actual stimulus consistent regardless of those fluctuations. On a fresh day an RPE 8 naturally lands at a higher weight; on a depleted day the same RPE is reached at a lower weight. The training effect stays stable even when the number on the bar changes.
The practical range for most lifting
- RPE 6 to 7 (3 to 4 RIR): technique work, warm-up sets, deloads, and volume days where you accumulate reps without heavy fatigue.
- RPE 8 to 9 (1 to 2 RIR): most working sets for hypertrophy and strength. Close enough to failure for a strong stimulus, far enough to maintain form and session quality.
- RPE 10 (failure): used sparingly, mainly for testing a true max or a final isolation set. Frequent failure adds fatigue faster than it adds strength.
How accurate is perceived exertion?
Beginners tend to underestimate proximity to failure, rating a 7 as a 9 because the set felt hard without them knowing there was more. The calibration improves with experience. A useful check: after stopping a set at RPE 8, could you have done two more reps with reasonable form? If yes, the rating was accurate.
Tracking RPE alongside your lifts
Logging RPE with weight and reps turns your training history into a calibration tool. You can see whether last week's RPE 8 at 100 kg became this week's RPE 7: objective evidence of progress independent of rep count. It also flags when a weight is drifting toward RPE 9 or 10, signaling it is time to deload or reassess.
Log RPE in the notes field alongside every set in Progressive Overloader so the history tells you not just what you lifted but how it felt.
For keeping weights moving session to session, see how much weight to add each week.
Common questions
- What does RPE 8 mean in lifting?
- RPE 8 means the set felt like an 8 out of 10 effort, leaving roughly 2 reps in reserve before failure. It is a standard working-set intensity for most strength and hypertrophy training.
- What is RIR in training?
- RIR stands for Reps in Reserve: how many more reps you could perform before reaching absolute failure. A set with 2 RIR means you stopped two reps short of failure, which is the same as RPE 8. The two scales describe the same thing from opposite directions.
- Should I train to failure every set?
- Not every set. Training close to failure is productive, but reaching it repeatedly adds fatigue without proportional strength gain. Most coaches recommend RPE 8 to 9 (1 to 2 RIR) for working sets, reserving true failure for the last set of select exercises.
- How do I know if my RPE rating is accurate?
- After stopping a set, ask: could I have done two more reps with reasonable form? If yes and you rated it RPE 8, the rating was accurate. Beginners usually overestimate their proximity to failure; accuracy improves over months of consistent logging.