RPE vs RIR: Which Should You Use?

RPE and RIR are two ways to describe how close a set was to failure. They often point to the same training effort, but the questions sound different.

If you are deciding which mode to use in the LogWise RPE/RIR calculator, the short answer is:

• Choose RIR if you naturally think, “How many good reps did I have left?”
• Choose RPE if your program gives you an RPE target or you already use a 1–10 effort scale.

You do not need to track both. Pick the language you can estimate most consistently.

RPE and RIR in plain English

RPE stands for Rate of Perceived Exertion. In strength training, it usually uses a 1–10 scale to rate how hard a completed set felt. The useful end of the scale is commonly RPE 6–10: an RPE 10 set is a maximum effort, while an RPE 8 set leaves some room.

RIR stands for Reps in Reserve. It asks how many more clean, technique-consistent reps you believe you could have completed before failure. If you finish a set and think you had two more good reps, that set was 2 RIR.

Both are estimates. They become more useful when you log them regularly and compare your ratings with what actually happens in later sets.

The main difference

RPE rates the set on an effort scale. RIR counts the estimated reps left.

For many lifters, RIR is easier at first because the question is concrete: “Could I have done one, two, or three more reps?” RPE may feel more natural when a coach writes targets such as “work up to one set of five at RPE 8.”

Neither method is automatically more accurate. Consistency matters more than the label. Switching between them from set to set can make your log harder to compare without adding useful information.

Simple RPE-to-RIR conversion

Reps in Reserve	Approximate RPE
RIR 4	RPE 6
RIR 3	RPE 7
RIR 2	RPE 8
RIR 1	RPE 9
RIR 0	RPE 10

This is not exact mathematics. It is a practical estimate for translating one effort scale into the other. Exercise choice, rep range, fatigue, technique, and your experience with hard sets can all affect the rating.

Also, 0 RIR does not mean you failed a rep. It means you completed the set but estimate that another clean rep was not available.

When should you use RPE?

RPE is a good choice when:

• Your coach or program already prescribes RPE targets.
• You use autoregulated top sets, heavy doubles, or singles.
• You are comfortable judging overall set difficulty on a 1–10 scale.
• You want to keep your log in the same format as an existing RPE-based program.

For example, “one top set at RPE 8” lets you adjust the weight to match your readiness that day. On a strong day you may lift more; on a tired day you may reduce the load while keeping the intended effort.

When should you use RIR?

RIR is often the simpler choice when:

• You are new to effort-based training.
• Your main goal is hypertrophy and most work uses moderate or higher rep ranges.
• You already think in terms of stopping a set with one, two, or three reps left.
• You want a direct note beside weight and reps in your workout log.

A target such as “3 sets of 8–12 at 2 RIR” gives you a clear stopping rule: end each working set when you believe two clean reps remain. This is usually easier to interpret than inventing an RPE number after the set.

Which mode should you choose in the LogWise calculator?

Use the mode that matches the information you actually have:

• If your log says RPE 8, select RPE and enter 8.
• If your log says 2 reps left, select RIR and enter 2.
• If you are starting from scratch, select RIR unless your program specifically uses RPE.

The two inputs describe roughly the same effort when you use the conversion above. Do not convert an RPE to RIR and then mentally adjust it again. Enter the clearest estimate once and let the RPE/RIR calculator use it.

The calculator can add effort context to an estimated max or target load, but the result is still an estimate. For a simpler calculation based only on a completed set’s weight and reps, use the one-rep max calculator.

Effort is only one part of training load. If you are also changing sets, reps, or weight across a session, the workout volume calculator can help you compare total work.

Example: the same set in both modes

Suppose you bench press 80 kg for 8 reps. After the eighth rep, you believe you could have completed two more clean reps, but probably not a third.

• In RIR language: 80 kg × 8 @ 2 RIR
• In RPE language: 80 kg × 8 @ RPE 8

In the LogWise calculator, choose either RIR 2 or RPE 8. You should not enter RPE 8 and then subtract two again; these are two descriptions of the same estimated effort.

If you later perform 80 kg for 9 reps at the same 2 RIR, that is a useful sign of progress. The load stayed the same, the effort target stayed similar, and you completed more work.

The practical answer

Use RIR if you want the clearest starting point: count the good reps you think were left. Use RPE if your program already speaks in RPE or you prefer a 1–10 effort score.

Whichever you choose, keep the method consistent, treat the number as an estimate, and log it beside the weight and reps. A repeatable estimate is more useful than switching scales in search of false precision.