RPE vs RIR: What They Mean and How to Use Them
RPE vs RIR explained: RPE 8 means 2 reps in reserve. Get an RPE chart with percentages, lb and kg examples, and how many reps in reserve to leave per set.
By the Liftly team · · 10 min read
RPE and RIR are two ways to say how hard a set was. Once you know how they line up, you can read any program that uses either one.
The short answer: RIR (reps in reserve) is how many more reps you could have done. RPE (rate of perceived exertion) is the same thing on a 1–10 scale: RPE = 10 − RIR. So RPE 10 means no reps left (0 RIR), RPE 9 means 1 rep left, and RPE 8 means 2 reps left. A set of 185 lb × 8 at RPE 8 means you could have done about 10.
This guide gives you a conversion table, an RPE chart with percentages of your max, worked examples in lb and kg, and how many reps in reserve to leave for muscle or strength. Every number in the tables was calculated with a script.
RPE vs RIR: the conversion table
The lifting RPE scale most programs use today is built on reps in reserve. A 2016 study by Zourdos and colleagues (with Eric Helms) tested this RIR-based scale on squatters and defined it exactly this way: RPE 10 = 0 RIR, RPE 9 = 1 RIR, and so on. The authors called it a practical way to adjust daily training load.
| RPE | RIR | What it feels like |
|---|---|---|
| 10 | 0 | Couldn't do another rep or add any weight |
| 9.5 | 0–1 | No more reps, but maybe a little more weight |
| 9 | 1 | One more rep, no more |
| 8.5 | 1–2 | Definitely one more, maybe two |
| 8 | 2 | Two more reps |
| 7 | 3 | Three more reps, bar still moving fast |
| 6 | 4 | Four or more left; a solid warm-up feel |
| 5 and below | 5+ | Warm-up weight |
Below RPE 6 the scale gets vague. Nobody can tell 6 reps left from 7, so treat anything easier than RPE 6 as "warm-up."
RPE vs RIR: which one should you use?
They are the same scale written two ways, so pick the one that's easier to think about mid-set.
- RIR is easier for most people. "How many more could I do?" is a concrete question. Most lifters can answer it without learning a new scale.
- RPE is what most powerlifting programs are written in. If your program says "3 × 5 @ RPE 8," you'll need to read RPE anyway. Translate it: 5 reps with 2 left.
- Half points (RPE 8.5, 9.5) only exist in RPE. They are handy for heavy singles and doubles, where "one more rep" and "a bit more weight" are different answers.
Whichever you use, write it down next to the set. A rating you don't record can't help you pick next week's weight.
RPE chart with percentages (lifting)
The chart below turns reps and RPE into a percentage of your one-rep max. We built it from the Epley formula, the same formula behind our 1RM guide: add the reps you did to the reps you had left, then work out what percentage of your max that many reps to failure is. A single at RPE 10 is shown as 100%, your max.
| Reps | RPE 10 | RPE 9.5 | RPE 9 | RPE 8.5 | RPE 8 | RPE 7 | RPE 6 |
|---|---|---|---|---|---|---|---|
| 1 | 100% | 95.2% | 93.8% | 92.3% | 90.9% | 88.2% | 85.7% |
| 2 | 93.8% | 92.3% | 90.9% | 89.6% | 88.2% | 85.7% | 83.3% |
| 3 | 90.9% | 89.6% | 88.2% | 87.0% | 85.7% | 83.3% | 81.1% |
| 4 | 88.2% | 87.0% | 85.7% | 84.5% | 83.3% | 81.1% | 78.9% |
| 5 | 85.7% | 84.5% | 83.3% | 82.2% | 81.1% | 78.9% | 76.9% |
| 6 | 83.3% | 82.2% | 81.1% | 80.0% | 78.9% | 76.9% | 75.0% |
| 7 | 81.1% | 80.0% | 78.9% | 77.9% | 76.9% | 75.0% | 73.2% |
| 8 | 78.9% | 77.9% | 76.9% | 75.9% | 75.0% | 73.2% | 71.4% |
| 9 | 76.9% | 75.9% | 75.0% | 74.1% | 73.2% | 71.4% | 69.8% |
| 10 | 75.0% | 74.1% | 73.2% | 72.3% | 71.4% | 69.8% | 68.2% |
Two things to notice:
- Moving one RPE point is the same as moving one rep. 5 reps at RPE 9 is the same percentage (83.3%) as 6 reps at RPE 10. That's the whole idea: RPE just counts the reps you didn't do.
- "RPE 8 = 80%" is wrong. RPE 8 is 90.9% of your max for a single and 71.4% for a set of 10. The percentage depends on the reps.
You'll find other RPE charts online with slightly different numbers. The popular powerlifting charts were built from coaches' data, not from a formula, and they run a few percent apart from this one in places. None of them is exact for you. Use a chart to pick a starting weight, then let how the set feels decide the rest.
How to use RPE to pick your weight (worked examples)
Say your program says 5 reps at RPE 8 and your estimated max on bench is 250 lb (or 112.5 kg if you train in kg). From the chart, 5 reps at RPE 8 is 81.1% of your max:
- 250 × 0.811 = 202.7 lb → load 200 lb.
- In kg: 112.5 × 0.811 = 91.2 kg → load 90 kg.
We round down to the nearest 5 lb or 2.5 kg plate jump, because starting a little light and letting RPE tell you to add weight beats missing reps.
More from the same 250 lb (112.5 kg) max, rounded down the same way:
| Prescription | % of max | lb (250 lb max) | kg (112.5 kg max) |
|---|---|---|---|
| 3 reps @ RPE 9 | 88.2% | 220 lb | 97.5 kg |
| 5 reps @ RPE 8 | 81.1% | 200 lb | 90 kg |
| 8 reps @ RPE 8 | 75.0% | 185 lb | 82.5 kg |
| 10 reps @ RPE 7 | 69.8% | 170 lb | 77.5 kg |
Then adjust on the day. If your first set of 200 × 5 felt like RPE 9.5, take 5–10 lb (2.5–5 kg) off for the next set. If it felt like RPE 6, add 5–10 lb. That daily adjustment is called autoregulation, and it's the main reason to use RPE at all: on a bad-sleep day you still hit the right effort, just with a bit less weight.
Why RIR matters for your estimated max
Estimated-max formulas assume you took the set close to failure. If you left reps in the tank, the estimate comes out low. The fix is simple: add your RIR to your reps before you calculate.
Example: 185 lb × 8 at RPE 8 (2 RIR).
- Calculated from 8 reps: 185 × (1 + 8 ÷ 30) = 234.3 lb.
- Calculated from 10 reps (8 done + 2 left): 185 × (1 + 10 ÷ 30) = 246.7 lb (111.9 kg).
That's a 12 lb gap from the same set. Here's the same weight, 225 lb × 5, rated at different RPEs:
| Set | RPE | Reps to failure | Estimated max |
|---|---|---|---|
| 225 lb × 5 | 10 | 5 | 262.5 lb (119.1 kg) |
| 225 lb × 5 | 9 | 6 | 270.0 lb (122.5 kg) |
| 225 lb × 5 | 8 | 7 | 277.5 lb (125.9 kg) |
| 225 lb × 5 | 7 | 8 | 285.0 lb (129.3 kg) |
In kg, 100 kg × 5 works out to 116.7 kg at RPE 10, 120 kg at RPE 9, 123.3 kg at RPE 8 and 126.7 kg at RPE 7.
One warning: people tend to underrate how many reps they have left, especially on high-rep sets and when they're new. If your RPE 7 sets keep producing a max you can't actually lift, rate harder.
How many reps in reserve should you leave?
There's no single right number, but the research gives a direction. A 2024 series of meta-regressions by Robinson, Zourdos and colleagues estimated RIR across many training studies. They found that muscle growth improved as sets were taken closer to failure, while strength gains were similar across a wide range of RIR. The authors flag that the RIR values were estimated from study descriptions, so treat it as a trend, not an exact number.
Rules of thumb most coaches use, which line up with that:
| Goal | Typical RIR | RPE |
|---|---|---|
| Muscle growth (hypertrophy) | 0–3 RIR | RPE 7–10 |
| Strength on big lifts (squat, bench, deadlift) | 1–3 RIR | RPE 7–9 |
| Isolation and machine work | 0–2 RIR | RPE 8–10 |
| Beginners learning the lifts | 2–3 RIR | RPE 7–8 |
| Deload week | 4+ RIR | RPE 6 or less |
Why stop short of failure on the big lifts? Form tends to break down on grinding reps, and sets to failure on squats and deadlifts leave you more tired for the next session. On a cable fly or leg extension, going to failure costs little, so you can push closer.
How to get better at rating RPE
Rating reps in reserve is a skill. New lifters are usually off by a few reps. These habits close the gap fast:
- Rate right after the set, not later. Write the RPE down while you still remember the last rep.
- Test it now and then. On a safe exercise (machine, dumbbell, or bench with a spotter), take the last set of the day to failure and see how many reps you really had. If you said RPE 8 and got 5 more reps, you were at RPE 5.
- Watch bar speed. The 2016 study found that average bar speed dropped as RPE rose. If the last rep was clearly slower than the first, you're probably at RPE 8 or higher.
- Compare with last time. If last week you did 200 × 5 and this week 200 × 7 felt the same, you got stronger. That's why logging the reps every session matters more than the rating itself.
How to track RPE and RIR in your log
Liftly doesn't have an RPE field yet, so here's a simple way to use effort ratings with it, or with any log:
- Log your actual reps. Liftly fills in last session's weight when you open an exercise and shows last time's reps as grey hints, so you can see at a glance whether today's 5 reps at that weight is more or less than last time.
- Write the RPE in your program or a note if you're following an RPE-based plan.
- Do one hard top set. Liftly works out your estimated 1RM from each set you log, without an RIR adjustment. A set taken to RPE 9–10 gives the truest number. (A logged single counts as weight × 1.033, a quirk of the formula.) Sets with 3–4 reps left will make your estimated max, and anything built on it, read low.
That last point also matters for ranks. A 180 lb (81.6 kg) lifter who logs 185 lb × 8 gets an estimated bench max of 234.3 lb, a 1.30× bodyweight ratio, which is Semi-Pro II for chest in Liftly Pro (with bench as their only chest exercise). If that set was really RPE 8 and they'd done all 10 reps, the estimate would be 246.7 lb (1.37×), Semi-Pro III. Same strength, different rank, just from the reps left in the tank. For what those levels mean in plain numbers, see how much you should bench for your weight.
If you want the bigger picture of using these numbers week to week, our guide on how to track progressive overload covers double progression and what to do when you stall.
FAQ
What does RIR mean in the gym?
RIR stands for reps in reserve: how many more reps you could have done with good form when you ended the set. 0 RIR means you couldn't do another rep. 2 RIR means you stopped with two left.
What does RPE 8 mean?
RPE 8 means you could have done about 2 more reps (2 RIR). If you did 5 reps at RPE 8, you could have done about 7 in total.
Is RPE the same as RIR?
For lifting, yes: they measure the same thing. RPE = 10 − RIR. The only extra in RPE is half points like 9.5, which means you couldn't do another rep but could have added a little weight.
How many reps in reserve for hypertrophy?
Most coaches use 0–3 RIR (RPE 7–10) for muscle growth. Research suggests growth improves as sets get closer to failure, so isolation work can go to 0–1 RIR, while big lifts usually stay at 1–3 to keep form clean.
How many reps in reserve for strength?
Usually 1–3 RIR (RPE 7–9) on the main lifts. Strength gains in research were similar across a wide range of RIR, so there's little reason to grind every set to failure.
Is RPE 8 80% of my max?
No. RPE describes effort, not a fixed percentage. RPE 8 is about 91% of your max for 1 rep, 81% for 5 reps and 71% for 10 reps, per the Epley-based chart above.
How many reps in reserve is RPE 7?
RPE 7 is 3 reps in reserve. The bar should still be moving at a good speed on your last rep.
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