Understanding RPE and RIR — How to Gauge Training Intensity

Ask most gym-goers how hard they trained today and you'll get a vague answer. "Pretty hard." "Good session." "I was sweating a lot." These impressions don't tell you much — and they don't help you train more effectively next time.

RPE and RIR are two related frameworks for quantifying training intensity in a way that's actually useful. Once you understand them, you'll have a far clearer picture of whether you're training hard enough, too hard, or not nearly hard enough.

What is RPE?

RPE stands for Rate of Perceived Exertion. In the context of strength training, it typically uses a 1–10 scale where:

• RPE 10 — Maximal effort. Could not have done another rep.
• RPE 9 — Could have done 1 more rep with perfect form.
• RPE 8 — Could have done 2 more reps.
• RPE 7 — Could have done 3 more reps. Still had significant left in the tank.
• RPE 6 and below — Light work, warm-up territory.

RPE was originally developed for cardiovascular exercise (the Borg scale) but has been widely adopted in powerlifting and strength training communities as a way to autoregulate training intensity.

What is RIR?

RIR stands for Reps In Reserve. It's essentially the inverse way of expressing the same concept. Where RPE 8 means "could have done 2 more reps," 2 RIR means exactly the same thing.

Some coaches and athletes find RIR more intuitive because it's more concrete: instead of assigning a number to how hard something felt, you estimate how many reps you had left in the tank.

Both scales describe the same thing. Use whichever resonates more with how you think about training.

Why not just use percentages?

Many classic programmes prescribe loading as a percentage of your one-rep max (1RM). Work up to a calculated 1RM, then do 75% of that for your working sets. Simple in theory.

The problem is that your 1RM isn't constant. It fluctuates based on sleep quality, stress, nutrition, time of day, warm-up quality, and accumulated fatigue. A weight that represents 80% of your max when you're well-rested and fresh might be 90% on a heavy training week with poor sleep. The same prescription produces wildly different training stimuli on different days.

RPE-based training adapts to your actual state. If your "8 RPE" set feels heavier than usual today, you naturally use less weight — and you're training at the intended intensity despite the variation. The load adjusts to you, rather than you fighting to hit a number that may no longer be appropriate.

How accurate are RPE estimates?

Novice lifters are notoriously poor at estimating RPE. The most common error is underestimating proximity to failure — thinking you have 3 reps left when you actually have 1, or thinking you have 1 rep left when you could have done 3 more.

This is a skill that develops over time with deliberate practice. The best way to calibrate is to occasionally take a set to genuine failure so you know what it actually feels like. Once you know what RPE 10 is, RPE 8 and 9 become much easier to identify.

Experienced lifters can gauge RPE with remarkable accuracy — within half a point consistently.

Practical application

For hypertrophy: Most evidence suggests working in the RPE 7–9 range (1–3 RIR) maximises muscle growth. You need to be close enough to failure to create a meaningful stimulus, but not grinding every set to the limit — which impairs recovery and increases injury risk.

For strength: Heavy strength work is often done at RPE 8–9 on main lifts. Top singles or competition simulations might be RPE 9–10. Accessory work can drop to RPE 7–8.

For warm-ups: Use RPE 5–6 or lower. Warm-up sets should never feel like work.

Logging RPE makes your training data more useful

Weight and reps alone don't tell the full story. If you benched 100kg × 8 reps at RPE 9 one week and 100kg × 8 reps at RPE 7 the following week, something changed — you got stronger, recovered better, or your technique improved. That context is invisible if you only log the numbers.

Adding an RPE note to each working set turns your log into a much richer record of how your training is actually going. Over time, you can see trends in how your perceived effort changes relative to your loads — a clear signal of fitness adaptation.

VoluLog lets you add notes to any set, making it easy to record RPE alongside your standard reps and weight data.

The bottom line

RPE and RIR are practical tools, not just theoretical concepts. They make your training self-correcting — you push harder on good days and pull back on hard ones, always training at an appropriate intensity rather than blindly chasing a number.

Learn to estimate your RIR honestly, log it alongside your sessions, and you'll have a much clearer picture of how your training is progressing — and a much better tool for knowing when to push and when to back off.