RPE vs RIR: The Difference and Why It Matters for Programming

TL;DR

RPE is “rating of perceived exertion” on a 10-point scale, anchored to reps left in reserve. RIR is “reps in reserve”, a count of how many more reps the lifter could have done.

Mathematically, RPE 10 = RIR 0, RPE 9 = RIR 1, RPE 8 = RIR 2, etc. They map cleanly. Practically, they communicate slightly different things to a lifter, and the choice between them affects compliance.

For working coaches: pick one phrasing per client and stick with it. Don’t switch between them mid-program.

The mapping

Read top to bottom or bottom to top. Same scale, two phrasings.

Where they came from

The modern resistance-training RPE scale was published by Zourdos et al in 2016 as a refinement of the Borg cardiovascular RPE scale. The Zourdos team validated their scale against velocity-based measurements: lifters’ reported RIR matched their actual remaining reps within ±1 rep across trained populations.

Mike Tuchscherer’s Reactive Training Systems (2010) had been using RPE in powerlifting for years prior. Tuchscherer’s table mapping (reps × RPE → percentage of 1RM) is what most modern coaching software uses. Coach Sheet’s RPE calculator ships with this table.

When the choice between them matters

For most lifters, they’re interchangeable. For a few specific cases, the framing affects compliance:

Novice lifters consistently rate RPE more accurately when asked in RIR terms. “How many more reps could you have done?” is a concrete question. “What was your RPE?” requires the lifter to have internalised the scale, which takes 4-8 weeks of training.

Powerlifting clients use RPE more naturally because the powerlifting community standardised on RPE in 2010s. They know the scale already.

Cyclical thinkers (clients who plan their training in their head before the session) prefer RPE as a target (“today’s top set is RPE 8”) because it lets them work backwards to load. RIR sounds reactive (“I left 2 in reserve”) rather than prescriptive.

Compliance-anxious clients sometimes treat RPE 8 as failure (“I rated it 8 because it felt hard”). For them, RIR 2 is clearer (“you should have been able to do 2 more”).

Programming with one or the other

Most programs prescribe one of these patterns:

Pattern 1, RPE-capped top set with backoff sets

• Top set: 3-5 reps to RPE 8-9
• Backoff: 4 sets at 80% of top set’s load

Pattern 2, RIR-anchored straight sets

• All sets: 5-8 reps with RIR 2 throughout

Pattern 3, Daily wave with RPE bands

• Mon: 5×5 RPE 6-7 (technical)
• Wed: 4×5 RPE 7-8 (volume)
• Fri: 3×5 RPE 8-9 (intensity)

The three patterns are interchangeable in terms of the math; the choice depends on coach style and client temperament.

Common confusion

“My RPE 8 felt different last week.” This is normal. RPE adjusts for your daily readiness — that’s the whole point. Same prescribed RPE on a tired day means lower load. The autoregulation is doing its job.

“What about RPE 11 or 12?” No such thing. The scale tops out at 10 (true failure). Some strength communities use “+1, +2” annotations for sets pushed past failure (forced reps, rest-pause), but those aren’t RPE.

“My set was RPE 8 but I missed the last rep.” Then it was RPE 9.5 or 10. RPE measures what happened, not what was prescribed. Log honestly.

“I’m prescribed RPE 8 for 5 reps but the calculator says different load than my body says.” Trust your body, log your actual load and reps, and tell the coach. The calculator gives a starting prescription based on population averages; individual lifters drift 2-5% from the average.

Why it matters for the coaching tool

Coach Sheet captures both as separate columns on every workout row:

• Prescribed RPE: what the coach planned (e.g., RPE 8)
• Achieved RPE: what the client rated the set after lifting it
• RIR: optional column, mostly for novice clients

Save Week reads the achieved RPE alongside the load to decide progression. RPE 9-10 with target reps hit = hold load. RPE 6-7 with target exceeded = bump load. RPE 10 with reps missed = reduce or technique check. The system can’t autoregulate without honest RPE feedback, which is the single biggest “what makes this work” prerequisite for every coach we interviewed.

Practical recommendation

For a new client:

1. Use RIR for the first 4-6 weeks while they learn the scale. “How many more reps could you have done?” is concrete.
2. Around weeks 4-8, start using both terms in coaching notes. “This set should feel like RPE 8, two reps in reserve.”
3. After 8 weeks, drop to RPE only. They’ve internalised the scale.

For an experienced client:

Use RPE from day one. They probably already use it.

The phrasing is less important than the consistent honest feedback. A client who rates accurately in either system is going to outprogram a client who fudges either system.