acalculator

What should I lift at my target RPE?

Type a set you just did, its reps and how hard it felt on the RPE scale. The RPE calculator estimates your one rep max and the weight to load for the next set at the reps and RPE you plan.

Your numbers

Units
Weight for the target set
247.5 lb

From 225 lb × 5 at RPE 8: 2 reps left, load 247.5 lb for 3 reps at RPE 9: 1 rep left.

Estimated one rep max
270 lb
Reps in reserve
2
Target reps in reserve
1
Target as % of 1RM
91.7%

Weight for the target set: 247.5 lb. From 225 lb × 5 at RPE 8: 2 reps left, load 247.5 lb for 3 reps at RPE 9: 1 rep left.

How to calculate

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.

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.

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).

  • 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.

Machine-readable copies: Markdown, JSON.

Worked examples

Each example is checked against the calculator on every build.

  1. 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 gives Estimated one rep max 270 lb, Weight for the target set 247.5 lb, Reps in reserve 2, Target as % of 1RM 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. Weight lifted 220.5 lb, Reps done 1, RPE of that set RPE 10: no reps left, Target reps 5, Target RPE RPE 10: no reps left gives Estimated one rep max 220.5 lb, Weight for the target set 196 lb, Target as % of 1RM 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. Weight lifted 308.6 lb, Reps done 6, RPE of that set RPE 7.5: 2.5 reps left, Target reps 8, Target RPE RPE 8: 2 reps left gives Reps in reserve 2.5, Estimated one rep max 389.9 lb.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

How it works

  1. Reps in reserve RIR = 10 − RPE. The scale runs from RPE 6 (4 in reserve) to RPE 10 (none) in steps of 0.5; a half point counts as half a rep (RPE 8.5 = 1.5 in reserve).
  2. Reps to failure n = reps done + RIR.
  3. Estimated one rep max 1RM = weight × 36 ÷ (37 − n) (Brzycki).
  4. Target set: n₂ = target reps + (10 − target RPE), and the weight to load = 1RM × (37 − n₂) ÷ 36.
  5. Target as % of 1RM = (37 − n₂) ÷ 36 × 100.

Rules. Weight is more than 0 and at most 2,000 lb (907.18474 kg). Reps and target reps are whole numbers from 1 to 10. RPE and target RPE are picked from a list, 6 to 10 in steps of 0.5. Reps plus reps in reserve must be 10 or fewer for each set; otherwise the page gives no answer and says which set.

Output format. Decimals and significant figures below are the most shown; trailing zeros are dropped (23.0 shows as 23, money keeps its cents). Weights show 1 decimal in lb (kg in Metric), rounded half up from the decimal value; 1 lb = 0.45359237 kg exactly. Reps in reserve show as typed (2, 2.5). The percentage shows 1 decimal. The page does not round to plates.

Assumptions

  • Your RPE ratings are honest and close to the reps you really had left.
  • Brzycki’s equation fits the lift; it tends to underestimate some lifts and lifters.

Worked examples by hand

225 lb × 5 at RPE 8, then 3 at RPE 9. RIR = 2, n = 7, 1RM = 225 × 36 ÷ 30 = 270 lb. n₂ = 3 + 1 = 4; weight = 270 × 33 ÷ 36 = 247.5 lb, 91.7% of the max.

A single at RPE 10, then 5 at RPE 10. n = 1, 1RM = 100 × 36 ÷ 36 = 100 kg. n₂ = 5; weight = 100 × 32 ÷ 36 = 88.9 kg (88.9%).

140 kg × 6 at RPE 7.5. RIR = 2.5, n = 8.5, 1RM = 140 × 36 ÷ 28.5 = 176.8 kg. A target of 8 reps at RPE 8 is n₂ = 10, the most the estimate allows: 176.84 × 27 ÷ 36 = 132.6 kg.

Other questions people ask

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).