RIR and RPE Load Calculator
Enter your one rep max (an estimate is fine) and get a table of working weights for common rep targets at 0-4 reps in reserve.
Your results
Estimates for healthy adults, for education only. Not a medical assessment. Built and reviewed by Umair Hazrami.
How this calculator works
A set of 8 reps with 2 left in the tank uses roughly the same load as your 10-rep max. So the calculator adds your target reps and your RIR together, treats that total as “reps to failure”, and works out the load with the Epley equation run in reverse:
Load = 1RM ÷ (1 + (reps + RIR) ÷ 30)
Each load is rounded to the nearest 2.5 kg. The table covers 1, 3, 5, 6, 8, 10, 12 and 15 reps at RIR 0-4. RPE is labelled as 10 minus RIR, the same scale used in a 2016 study of experienced and novice squatters, where RPE 10 equals 0 RIR, RPE 9 equals 1 RIR, and so on (Zourdos et al., 2016).
A quick worked example with a 100 kg 1RM:
- 8 reps at RIR 2 (RPE 8) → 10 reps to failure → 100 ÷ 1.333 = 75 kg
- 5 reps at RIR 1 (RPE 9) → 6 reps to failure → 83.3 kg, shown as 82.5 kg
- 12 reps at RIR 3 (RPE 7) → 15 reps to failure → 66.7 kg, shown as 67.5 kg
One quirk: the formula is applied to every cell, including 1 rep at RIR 0. That cell shows about 97% of your 1RM (97.5 kg for a 100 kg max), not 100%. Treat it as a heavy single, not a true max.
Using the table in your training
Pick your rep target, pick your RIR, read off the weight. Then let the bar overrule the spreadsheet.
If your first set of 8 at “RIR 2” turns into a grinder, the table was too optimistic for you on that lift today. Drop 2.5-5 kg. If it flies up, add some. Writing down the load, reps and your honest RIR in a logbook makes this easier over time. The plate calculator handles the loading.
For muscle growth, most working sets at RIR 1-3 is a good default. A 2023 meta-analysis of 15 studies found a trivial edge for set failure overall, but no clear advantage when only momentary muscular failure was compared with stopping short (Refalo et al., 2023). The authors suggested the relationship between proximity to failure and growth may not be linear. More on that in our guide to training to failure versus leaving 1-3 RIR. Count those hard sets per week with the training volume calculator.
Limitations
The table is only as good as two inputs: your 1RM and your RIR guess.
Get the 1RM from a recent hard set with the 1RM calculator rather than an old gym PR. The reps-to-percentage formula is an average, so it fits some lifts and some people better than others, and it gets looser at higher reps.
RIR guesses are noisy. In 20 trained men, estimates on the first set of bench press and prone row were lower than the reps they actually had left, and accuracy improved by the third set (Mansfield et al., 2020). A study of 58 trained and untrained men and women on machine exercises also found predictions were more accurate closer to failure and in later sets, with sex and training experience making no significant difference (Remmert et al., 2023). Both used fairly small samples and a few exercises, so take them as a nudge, not a rule. Taking an isolation set to true failure now and then is a low-risk way to calibrate; our guide to how accurately lifters gauge RIR goes deeper.
Beginners can use the table, but expect bigger misses in the first few months. If you have a heart condition, high blood pressure or a current injury, get a doctor’s or physiotherapist’s go-ahead before pushing sets near failure.
Frequently Asked Questions
What is the difference between RIR and RPE?
RIR (reps in reserve) is how many more clean reps you could have done when you racked the bar. The RIR-based RPE scale simply counts down from 10, so RPE 10 means 0 RIR, RPE 9 means 1 RIR, and so on. This calculator uses that exact conversion: RPE = 10 minus RIR.
What RIR should I train at for muscle growth?
Most hard sets at 1-3 RIR are a sensible default. A 2023 meta-analysis of 15 studies found only a trivial growth advantage for failure across all definitions of failure, and no clear advantage when training to momentary muscular failure was compared with stopping short. Going to failure occasionally, mostly on safer machine and isolation work, is reasonable but not required.
How accurate is my RIR guess?
Less accurate than most lifters think, especially early in a set or on the first set of the day. Studies in trained and untrained people found predictions got better closer to failure and in later sets. In trained men, early sets tended to be rated harder than they really were, meaning more reps were left than estimated.
Why are the loads in the table different from my real sets?
The table uses one average formula linking reps to percentage of 1RM, and real people differ. Muscle fibre makeup, the exercise, fatigue from earlier sets and how accurate your 1RM is all shift the numbers. Use the table for your first set, then adjust the weight by feel.
Can I use an estimated 1RM instead of a tested one?
Yes, that is what most lifters should do. Run a recent hard set through the 1RM calculator and paste the result here. If the first week's sets feel clearly easier or harder than the target RIR, nudge your 1RM entry down or up by 2.5-5 kg.
Is training at RPE 10 dangerous?
For healthy lifters with solid technique, an occasional set at RPE 10 is a normal part of training. The catch is that form is more likely to break down near failure, especially on heavy squats and deadlifts. Use safety pins, a spotter or a machine when you plan to go to RPE 10. Anyone with heart disease, high blood pressure or a recent injury should ask a doctor before training to failure.
Sources & References
Every claim above is checked against peer-reviewed research (PubMed, U.S. National Library of Medicine) or guidance from established health bodies. How we fact-check.
- Zourdos MC, et al. Novel Resistance Training-Specific Rating of Perceived Exertion Scale Measuring Repetitions in Reserve. J Strength Cond Res. 2016. PMID: 26049792
- Refalo MC, et al. Influence of Resistance Training Proximity-to-Failure on Skeletal Muscle Hypertrophy: A Systematic Review with Meta-analysis. Sports Med. 2023. PMID: 36334240
- Remmert JF, et al. Accuracy of Predicted Intraset Repetitions in Reserve (RIR) in Single- and Multi-Joint Resistance Exercises Among Trained and Untrained Men and Women. Percept Mot Skills. 2023. PMID: 37036795
- Mansfield SK, et al. Estimating Repetitions in Reserve for Resistance Exercise: An Analysis of Factors Which Impact on Prediction Accuracy. J Strength Cond Res. 2020. PMID: 32881842