RPE Calculator: Find the Right Weight for Any Reps and RPE
Enter a set you did recently, or your 1RM, and this RPE calculator tells you what to load for your next set at any rep count and RPE. You also get your estimated 1RM, back-off set weights and a full RPE chart in your own numbers.
It works in kg or lb, rounds to the plates you have, and you can pick your effort as RPE or reps in reserve (RIR), since each option shows both.
Quick answer
Key takeaways
- RPE rates the last rep of a set by how many reps you had left, so RPE 8 means 2 reps in reserve (RIR).
- The chart links reps and RPE to a percentage of your 1RM, from 100% for a single at RPE 10 down to 57.4% for 12 reps at RPE 6.
- Heavier sets taken close to failure give the most reliable estimate, because lifters misjudge reps left more on long, easy sets.
- Back-off sets 1 to 2 RPE lighter let you add volume after a top set without grinding.
- In an 8-week study, RPE-based loading built strength and muscle as well as fixed percentages did.
How do you use the RPE calculator?
Enter one recent set, choose what you want to lift next and press Calculate. Every field has a default, so you can see a full result before typing anything.
- Pick your starting point. Choose “A recent set” and enter the weight, reps and RPE of a set from the last week or two. If you know your 1RM, choose “My 1RM” instead.
- Set your target. Enter the reps and RPE your program asks for, such as 3 reps at RPE 8.
- Choose your smallest jump. Pick 2.5 kg or 5 lb for a standard barbell with small plates, or 1 kg if you have fractional plates.
- Read the result. The big number is your load. Below it you get your estimated 1RM, the percentage of 1RM, a confidence note, back-off sets and the full chart with your target in red.
Ramp up to that first set with our warm-up set calculator, which lays out each warm-up weight and the plates to load. If your first set lands harder or easier than planned, enter that set as your new reference and recalculate. The next set will fit the day you are having.
How does the calculator work out your weight?
It uses two steps from Mike Tuchscherer’s Reactive Training Systems (RTS) RPE chart, the same chart most online RPE calculators use.
- Estimated 1RM = weight lifted ÷ chart percentage for your reps and RPE
- Target load = estimated 1RM × chart percentage for your target reps and RPE, rounded to your smallest jump
Worked example in pounds: 225 lb for 5 reps at RPE 8 sits at 81.1% on the chart, so 225 ÷ 0.811 = 277.4 lb. Three reps at RPE 8 sits at 86.3%, so 277.4 × 0.863 = 239.4 lb, which rounds to 240 lb with 5 lb jumps.
Formulas such as Epley and Brzycki assume every set went to failure, so they treat 5 reps at RPE 7 and 5 reps at RPE 10 the same. The RPE chart counts the reps you left in the tank. Our 1RM calculator does this too, but through the Brzycki formula, so the two can differ by a few percent: 100 kg for 5 reps at RPE 8 gives 120 kg there and 123.3 kg here. Both are estimates, and either works as a starting point.
RPE to percentage chart (1 to 12 reps)
Find your reps in the left column and your RPE across the top: the cell is the percentage of your 1RM. For example, 8 reps at RPE 9 is 76.2% of your 1RM. The RPE 8 column (2 reps in reserve) is marked in red as a reference point.
| Reps | RPE 10 | RPE 9.5 | RPE 9 | RPE 8.5 | RPE 8 | RPE 7.5 | RPE 7 | RPE 6.5 | RPE 6 |
|---|---|---|---|---|---|---|---|---|---|
| 1 | 100% | 97.8% | 95.5% | 93.9% | 92.2% | 90.7% | 89.2% | 87.8% | 86.3% |
| 2 | 95.5% | 93.9% | 92.2% | 90.7% | 89.2% | 87.8% | 86.3% | 85% | 83.7% |
| 3 | 92.2% | 90.7% | 89.2% | 87.8% | 86.3% | 85% | 83.7% | 82.4% | 81.1% |
| 4 | 89.2% | 87.8% | 86.3% | 85% | 83.7% | 82.4% | 81.1% | 79.9% | 78.6% |
| 5 | 86.3% | 85% | 83.7% | 82.4% | 81.1% | 79.9% | 78.6% | 77.4% | 76.2% |
| 6 | 83.7% | 82.4% | 81.1% | 79.9% | 78.6% | 77.4% | 76.2% | 75.1% | 73.9% |
| 7 | 81.1% | 79.9% | 81.1% | 77.4% | 76.2% | 75.1% | 73.9% | 72.3% | 70.7% |
| 8 | 78.6% | 77.4% | 76.2% | 75.1% | 73.9% | 72.3% | 70.7% | 69.4% | 68% |
| 9 | 76.2% | 75.1% | 73.9% | 72.3% | 70.7% | 69.4% | 68% | 66.7% | 65.3% |
| 10 | 73.9% | 72.3% | 70.7% | 69.4% | 68% | 66.7% | 65.3% | 64% | 62.6% |
| 11 | 70.7% | 69.4% | 68% | 66.7% | 65.3% | 64% | 62.6% | 61.3% | 59.9% |
| 12 | 68% | 66.7% | 65.3% | 64% | 62.6% | 61.3% | 59.9% | 58.6% | 57.4% |
Each step along a diagonal adds one rep and removes one rep in reserve, so the percentage stays the same. That is why 5 reps at RPE 10 and 3 reps at RPE 8 are both 86.3%: in both cases you could have done 5 reps in total. Some coaches build a personal version of this chart from a lifter’s own 1, 4 and 8 rep maxes, since some people can do more reps at a given percentage than the average chart predicts.
How accurate is the RPE calculator?
It is accurate enough to choose a starting weight, but two things limit it: how well you rate your sets, and how closely your own strength matches the average chart. Research on the first point is encouraging.
- In the study that tested this reps-in-reserve RPE scale, squatters’ RPE ratings rose as their bar speed slowed, with a strong link in both experienced lifters and beginners (Zourdos et al., 2016).
- A 2022 meta-analysis of 12 studies and 414 people found that lifters underpredicted their reps left by about one rep on average. Predictions were slightly better when made closer to failure, and errors grew much faster on sets longer than 12 reps (Halperin et al., 2022).
- Powerlifters who chose their own loads to hit a target RPE on the squat, bench press and deadlift landed within about 0.3 RPE of the target on average (Helms et al., 2017).
That is why the calculator shows a confidence note. It rates your estimate high for sets of 1 to 6 reps at RPE 7.5 or harder, medium up to 10 reps at RPE 7, and low for anything lighter or longer. If you are still learning to judge reps left, our guide to RPE vs RIR covers how to calibrate your ratings.
How should you use the back-off sets?
Do your top set at the target RPE, then drop to a back-off load for your remaining sets. The table gives four options: the same reps 1 or 2 RPE easier, and your top set minus 5% or 10%, with the RPE each drop works out to.
For example, do one top set of 3 reps at RPE 8, then 3 sets of 3 reps at RPE 7. The lighter sets add practice and volume while keeping fatigue under control. If a back-off set feels harder than its target RPE, take a little weight off for the next one; if it feels easier, finish the plan and use it to update your reference set next session.
This style of training holds up in research. In an 8-week study of trained men doing squats and bench presses with matched sets and reps, the group that picked loads by RPE gained strength and muscle as well as the group using fixed percentages, with a possible small strength advantage for RPE (Helms et al., 2018).
Frequently asked questions
What weight should I use for 5 reps at RPE 8?
Use 81.1% of your 1RM. With a 140 kg squat max, that is about 113.5 kg, which rounds to 112.5 kg or 115 kg depending on how the warm-ups felt.
Can I use the calculator for dumbbell or machine exercises?
Yes, but treat the result as a rough guide. The chart was built for barbell lifts, and isolation or machine exercises can allow more reps at the same percentage of 1RM.
Why doesn't the chart go above 12 reps?
Above 12 reps, lifters misjudge how many reps they have left much more, so a percentage chart stops being reliable. For high-rep sets, pick a weight by feel and use RPE only to decide when to stop.
How often should I update my reference set?
Enter a new set each week, or whenever your top set feels easier or harder than its RPE target. Recent sets reflect your current strength better than an old 1RM test.
Does training close to failure build more muscle?
A 2024 exploratory series of meta-regressions found that muscle growth improved as sets ended closer to failure, while strength gains were similar across a wide range of reps in reserve (Robinson et al., 2024). You can read more in our guide to training to failure.
Next step: plan this week’s top sets with the calculator, log the RPE of each one, and add weight once the same load feels a full RPE easier, following the principles of progressive overload.
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This calculator gives estimates, not medical advice. Heavy sets carry more risk when you are fatigued or new to a lift, so use a spotter or safety bars, and check with your doctor before training hard if you have an injury or a health condition.