Mesolab › Tools › RIR & RPE calculator
Reps in reserve (RIR) and RPE calculator
Enter one set you have done: the weight, the reps and how many reps you had left in reserve (RIR), or its RPE. Get your estimated 1RM and the weight to use for your next target.
Get this number beside every set
Mesolab suggests a weight for every set from your saved 1RM and the sets you log, aimed at that set's target RIR. Free to download; your first completed workout is free.
RIR chart: percentage of 1RM by reps and reps in reserve
Each cell is the weight that should leave that many reps in reserve, as a percentage of your 1RM. Read RPE as 10 minus RIR: the 2 RIR column is RPE 8.
| Reps | 0 RIR | 1 RIR | 2 RIR | 3 RIR | 4 RIR |
|---|---|---|---|---|---|
| 1 | 100% | 94% | 91% | 88% | 86% |
| 2 | 94% | 91% | 88% | 86% | 83% |
| 3 | 91% | 88% | 86% | 83% | 81% |
| 4 | 88% | 86% | 83% | 81% | 79% |
| 5 | 86% | 83% | 81% | 79% | 77% |
| 6 | 83% | 81% | 79% | 77% | 75% |
| 8 | 79% | 77% | 75% | 73% | 71% |
| 10 | 75% | 73% | 71% | 70% | 68% |
| 12 | 71% | 70% | 68% | 67% | 65% |
| 15 | 67% | 65% | 64% | 63% | 61% |
| 20 | 60% | 59% | 58% | 57% | 56% |
RPE to RIR chart
RPE and RIR describe the same thing from opposite ends: RIR counts the reps you had left, RPE rates the effort out of ten. Subtract RIR from 10 to get RPE.
| RPE | RIR | What the set felt like |
|---|---|---|
| 10 | 0 | No more reps possible. Failure. |
| 9.5 | 0–1 | Maybe one more rep, not certain. |
| 9 | 1 | One more rep, and it would have been a grind. |
| 8.5 | 1–2 | Definitely one more, maybe two. |
| 8 | 2 | Two more, the last one slow. |
| 7.5 | 2–3 | Two more for sure, maybe three. |
| 7 | 3 | Three more. Hard but controlled. |
| 6 | 4 | Four more. Moving quickly. |
| 5 and below | 5+ | Warm-up effort. |
How the calculator works
A set you stopped short of failure tells you what you could have done to failure: the reps you did plus the reps you had left. The calculator treats that total as your effective reps and uses the Epley formula:
Estimated 1RM = weight × (1 + (reps + RIR) ÷ 30)
Example: 185 lb for 8 reps at 2 RIR counts as 10 effective reps, so the estimated 1RM is 185 × (1 + 10 ÷ 30) = 246.7 lb, shown as 247.5 lb after rounding. For 10 reps at 2 RIR next time, divide by (1 + 12 ÷ 30): about 176 lb, or 175 lb on the bar.
The working weight runs the same formula backwards: your estimated 1RM divided by (1 + (target reps + target RIR) ÷ 30), rounded to the nearest 2.5 lb or kg. A single at 0 RIR is your 1RM, so it is used as it is.
This is the same formula Mesolab uses to estimate a 1RM from the sets you log. Epley stays sensible in the 8 to 20 rep range where most muscle-building sets live; formulas such as Brzycki drop off sharply there.
An estimate, not a test. Every rep-based 1RM formula is an approximation, and it is only as good as the RIR you enter. Experienced lifters usually judge RIR within about a rep; newer lifters often have several more reps in reserve than they think, which makes the estimate read low. Sets of 20 or fewer reps give the most useful numbers.
Common questions
How many RIR is RPE 7?
RPE 7 is 3 reps in reserve. RPE 8 is 2 RIR, RPE 9 is 1 RIR and RPE 10 is 0 RIR, or failure.
How do I calculate RIR?
You estimate it at the end of a set: if you had kept going with the same form, how many more reps would you have completed? Bar speed on the last rep is the best guide. If it slowed noticeably you were within two or three; if it nearly stalled, zero or one. The RIR guide covers how to calibrate the estimate.
What RIR should I train at to build muscle?
Most hypertrophy programs keep working sets at 1 to 3 RIR: close enough to failure that the last reps are hard, far enough from it that you can repeat the work across the week.
Why does RIR change the estimate so much?
185 lb for 8 at 0 RIR and 185 lb for 8 at 3 RIR are different sets. The first was your limit; the second had three reps to spare, so the same weight implies a stronger lifter. Leaving RIR out treats every set as a set to failure.
What is the difference between RIR and RPE?
None in what they measure. RIR counts the reps left in the tank; RPE rates the effort from 1 to 10. RPE 8 means 2 reps in reserve, so the calculator accepts either.
Should I use this instead of testing my 1RM?
For choosing training weights, an estimate from a hard set of 5 to 10 is usually enough and costs far less recovery than a max attempt. If you compete, test the lift itself.