# What should I lift at my target RPE?

Estimates your one-rep max from a set’s weight, reps and RPE (reps in reserve), and the weight to load for a target number of reps at a target RPE.

- Page: https://www.acalculator.org/sports/rpe-calculator
- JSON spec: https://www.acalculator.org/sports/rpe-calculator.json
- Version: 2b3f1ce57810

## Default answer

Example with the default inputs (Weight lifted 225 lb, Reps done 5, RPE of that set RPE 8: 2 reps left, Target reps 3, Target RPE RPE 9: 1 rep left): From 225 lb × 5 at RPE 8: 2 reps left, load 247.5 lb for 3 reps at RPE 9: 1 rep left.

## Inputs

| Key | Label | Description |
| --- | --- | --- |
| w | Weight lifted | The weight of the set you did, bar included. |
| r | Reps done | How many reps you did in that set, from 1 to 10. |
| rpe | RPE of that set | How hard the set was on the 6 to 10 RPE scale. |
| tr | Target reps | The reps you plan for the next set, from 1 to 10. |
| trpe | Target RPE | How hard the planned set should be, from 6 to 10. |

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| target | Weight for the target set | Estimated 1RM × (37 − target reps to failure) ÷ 36. |
| oneRm | Estimated one rep max | Weight × 36 ÷ (37 − reps to failure) (Brzycki). |
| rir | Reps in reserve | 10 − RPE: reps you could still have done. |
| targetRir | Target reps in reserve | 10 − target RPE. |
| percent | Target as % of 1RM | (37 − target reps to failure) ÷ 36 × 100. |

## Method

Reps in reserve = 10 − RPE; reps to failure n = reps + reps in reserve; 1RM = weight × 36 ÷ (37 − n); target weight = 1RM × (37 − n₂) ÷ 36, with n₂ = target reps + (10 − target RPE).

## Assumptions

- The RPE scale is the repetitions-in-reserve scale: RPE 10 = no reps left, 9 = 1, 8 = 2, 7 = 3, 6 = 4, and half points in between.
- Brzycki’s equation links a weight to the reps you could do to failure; it is meant for 10 reps or fewer, so reps plus reps in reserve must be 10 or fewer.

## Worked examples

1. w = 102.058283, r = 5, rpe = 8, tr = 3, trpe = 9 gives oneRm = 122.46994, target = 112.264112, rir = 2, percent = 91.666667%. Source: Helms et al., Application of the Repetitions in Reserve-Based Rating of Perceived Exertion Scale for Resistance Training, Strength and Conditioning Journal 38(4), 2016, https://doi.org/10.1519/SSC.0000000000000218 (RPE 8 = 2 reps in reserve, RPE 9 = 1); Brzycki, 1993, Strength testing: predicting a one-rep max from reps-to-fatigue, https://doi.org/10.1080/07303084.1993.10606684.
2. w = 100, r = 1, rpe = 10, tr = 5, trpe = 10 gives oneRm = 100, target = 88.888889, percent = 88.888889%. Source: Helms et al., Application of the Repetitions in Reserve-Based Rating of Perceived Exertion Scale for Resistance Training, Strength and Conditioning Journal 38(4), 2016, https://doi.org/10.1519/SSC.0000000000000218 (RPE 10 = maximum effort); Brzycki, 1993, Strength testing: predicting a one-rep max from reps-to-fatigue, https://doi.org/10.1080/07303084.1993.10606684.
3. w = 140, r = 6, rpe = 7.5, tr = 8, trpe = 8 gives rir = 2.5, oneRm = 176.842105. Source: Helms et al., Application of the Repetitions in Reserve-Based Rating of Perceived Exertion Scale for Resistance Training, Strength and Conditioning Journal 38(4), 2016, https://doi.org/10.1519/SSC.0000000000000218; Brzycki, 1993, Strength testing: predicting a one-rep max from reps-to-fatigue, https://doi.org/10.1080/07303084.1993.10606684.

## FAQ

### What does RPE mean in lifting?

RPE is the rating of perceived exertion. On the repetitions-in-reserve scale (Helms and others, 2016), the number says how many reps you had left: RPE 10 means none, 9 means one, 8 means two, and a half point such as 8.5 means one or two.

### How do I use RPE to pick a weight?

Estimate your max from a recent set, then work back. 225 lb for 5 at RPE 8 means about 7 reps to failure, which Brzycki’s equation turns into a 270 lb max. A triple at RPE 9 is 4 reps to failure, so load 270 × 33 ÷ 36 = 247.5 lb.

### How does the RPE chart turn into percentages?

Each reps-plus-reserve total maps to a share of your max: (37 − n) ÷ 36 with Brzycki’s equation. One rep at RPE 10 is 100%, 5 reps at RPE 10 is 88.9%, and 3 reps at RPE 8 (5 to failure) is also 88.9%.

### Why does the calculator stop at 10 reps to failure?

Brzycki built his equation for sets to fatigue of 10 reps or fewer, and estimates drift with more reps. So reps done plus reps in reserve must be 10 or fewer for both sets.

### Is RPE accurate?

It is a rating, so it varies from lifter to lifter and improves with practice. Helms and colleagues note that ratings are most precise close to failure, which is why sets at RPE 8 to 10 give the best estimates.

### What is the difference between RPE and RIR?

They are two ways of saying the same thing on this scale: reps in reserve = 10 − RPE. RPE 7 is 3 reps in reserve, RPE 9.5 is half a rep in reserve (no more reps, but a little more weight).

## Sources

- Helms, E. R., J. Cronin, A. Storey, and M. C. Zourdos (2016). Application of the Repetitions in Reserve-Based Rating of Perceived Exertion Scale for Resistance Training. Strength and Conditioning Journal 38(4), 42–49. https://doi.org/10.1519/SSC.0000000000000218 (retrieved 2026-10-01)
- Helms, E. R. and others (2018). RPE vs. Percentage 1RM Loading in Periodized Programs Matched for Sets and Repetitions. Frontiers in Physiology 9:247 (the RIR scale: 10 = maximal, 9.5 = no more reps but slightly more load, 9 = 1 RIR, 8.5 = 1–2 RIR, 8 = 2 RIR). https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2018.00247/full (retrieved 2026-10-01)
- Brzycki, M. (1993). Strength testing: predicting a one-rep max from reps-to-fatigue. Journal of Physical Education, Recreation and Dance 64(1), 88–90. https://doi.org/10.1080/07303084.1993.10606684 (retrieved 2026-10-01)