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RPE calculator

Short answer

On the strength training RPE scale, RPE 8 means you had about 2 reps left in reserve (RIR). A set of 5 at RPE 8 with 100 kg is treated as about 7 reps to failure, which gives an estimated one-rep max of about 121.7 kg, and a set of 3 at RPE 9 at about 109.4 kg. Rate the set straight after you finish it.

Last reviewed 27 October 20264 published sourcesNot medical advice

Reps keeps track of this for you on iPhone, iPad and Apple Watch.

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RPE calculator

Rate the set by how many more reps you could have done with good form, right after you rack it.

Unit
reps

1 to 10 reps

Enter the weight and reps of a set, and its RPE.

Runs entirely in your browser. Nothing you type is saved or sent anywhere.

The repetitions-in-reserve RPE scale
RPEReps in reserveWhat it feels like
100Maximal effort: no rep left
9.50.5No rep left, but a little more weight was possible
91One rep left
8.51.5One rep left, maybe two
82Two reps left
7.52.5Two reps left, maybe three
73Three reps left
64Four reps left (RPE 5–6 covers 4–6)
From the RIR-based scale of Zourdos et al. (2016). RPE 5–6 covers 4–6 reps in reserve.

How the calculator works

The strength training RPE scale ties each rating to the reps you could still have done (Zourdos et al., 2016). Lifters use it to choose loads day to day, by aiming for a rep target at an RPE rather than a fixed weight (Helms et al., 2016).

A set of reps at an RPE is treated as a set of reps plus reps in reserve taken to failure. That number goes through the Epley equation (LeSuer et al., 1997) and the Brzycki equation (Brzycki, 1993), and the average is your estimated 1RM. Half-step ratings such as 8.5 average the two neighbouring estimates.

For a 1RM from a set without an RPE, use the one rep max calculator. To decide when to add weight, see the progressive overload calculator.

Your sets, logged with their effort

Reps logs every set with its reps and weight and turns your training into a plan you can follow, on iPhone and Apple Watch.

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Common questions

What does RPE 8 mean in lifting?

On the repetitions-in-reserve scale, RPE 8 means you could have done about 2 more reps with good form. RPE 10 is no reps left, 9 is one left and 7 is three left.

What is the difference between RPE and RIR?

RIR is how many reps you had left; RPE is the 1–10 rating that goes with it. On the strength training scale they are two ways of saying the same thing: RPE = 10 − RIR for RPE 7 to 10.

How accurate is a 1RM estimated from RPE?

It is an estimate. People new to lifting tend to misjudge reps in reserve, especially far from failure, and the equations themselves get less reliable on longer sets. Sets close to failure (RPE 8–10) and of 10 reps or fewer give the most useful numbers.

Sources

Figures on this page were checked against these publications on 27 October 2026.

  1. Zourdos MC, Klemp A, Dolan C, Quiles JM, Schau KA, Jo E, Helms E, Esgro B, Duncan S, Garcia Merino S, Blanco R. Novel resistance training–specific rating of perceived exertion scale measuring repetitions in reserve. Journal of Strength and Conditioning Research. 2016;30(1):267–275. doi.org/10.1519/JSC.0000000000001049
  2. Helms ER, Cronin J, Storey A, Zourdos MC. Application of the repetitions in reserve-based rating of perceived exertion scale for resistance training. Strength and Conditioning Journal. 2016;38(4):42–49. doi.org/10.1519/SSC.0000000000000218
  3. LeSuer DA, McCormick JH, Mayhew JL, Wasserstein RL, Arnold MD. The accuracy of prediction equations for estimating 1-RM performance in the bench press, squat, and deadlift. Journal of Strength and Conditioning Research. 1997;11(4):211–213. doi.org/10.1519/1533-4287(1997)011<0211:TAOPEF>2.3.CO;2
  4. Brzycki M. Strength testing: predicting a one-rep max from reps-to-fatigue. Journal of Physical Education, Recreation & Dance. 1993;64(1):88–90. doi.org/10.1080/07303084.1993.10606684

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