Strength

RPE & Choosing Weights

How to use RPE and reps in reserve to pick the right weight, progress safely and keep training effective when sleep and stress change.

Rating of perceived exertion (RPE) is a 1–10 scale for how hard a set feels. In strength training it is usually paired with reps in reserve (RIR): how many more good repetitions you could have done.

In short: RPE 10 means nothing left; RPE 8 means about two clean reps in reserve. Pick a load that lands within one point of the prescribed RPE, and lower it if technique breaks down.

A woman holding a barbell overhead in a deep squat

Choose the load by effort and technique, not by the number on the bar.

RPE	Reps left in the tank	What it feels like
10	0	Maximum effort, no more reps possible
9	1	One more rep with everything you have
8	2	Hard but controlled; two clean reps left
7	3	Challenging and steady; speed stays crisp
5–6	4–6	Warm-up or technique work

Why use RPE

A fixed weight does not account for sleep, stress or how your body feels today. RPE keeps the training effect consistent when your capacity varies. Research on RIR-based scales found they track effort well in trained lifters, which is why coaches use them widely.

How to choose your weight

Pick a load you can lift with good technique for the prescribed reps.
After the set, ask: how many clean reps did I have left? Compare that with the target.
If you finished with several more reps than asked, add a small amount next set or session. If you could not complete the reps with good form, lower the load.
Aim to land within one point of the prescribed RPE.

A worked example

A split squat is prescribed as 3 × 8 at RPE 7 (three reps in reserve). You finish the first set and feel you could have done six more. That is closer to RPE 4–5, so add a little load. If you could only just finish with one rep spare (RPE 9), reduce the load slightly.

Known limits

People tend to underestimate how many reps they have left, especially when sets end well short of failure, and accuracy improves with practice. Treat RPE as a guide, not a measurement. Stop a set when technique breaks down, whatever the number says.

Aerobic sessions use RPE too

The same idea works for cardio on a 1–10 scale. Easy aerobic work sits around 3–4 out of 10, where you can speak in full sentences. See Aerobic Pacing.

Common mistakes

Chasing a heavier number regardless of how it feels.
Always rounding down to stay ‘safe’ rather than working within the prescribed range.
Ignoring pain that changes your movement. Sharp or joint pain is a reason to stop, not to grade as RPE.

Common RPE traps

Guessing high early. When sets are far from failure, people usually underestimate how many reps they have left. Add a rep or two to your guess until you get a feel for it.
Letting technique slip. If form breaks down, the set is over, whatever the number says.
Comparing across exercises. A split squat and a calf raise feel different at the same RPE. Judge each one on its own.
Chasing a heavier number every week. Progress in small steps and let the effort settle before you add more.

Myth versus evidence

Common belief	What the evidence suggests
Every set should be to failure.	Research on training proximity to failure suggests you can get strong training close to failure, not always at it, with less fatigue.
RPE is just a guess.	It is a rough estimate, but studies in trained lifters found it tracks effort reasonably well, and it improves with practice.

Coach’s tip: after each set, say the number out loud (‘that was an 8’). It builds the habit faster than trying to remember it.

Frequently asked questions

What RPE should warm-ups be?

Around 5–6: light enough to focus on technique.

Should every set be RPE 9?

No. Most work sits lower, leaving room to recover and to repeat the session next week.

Can beginners use RPE?

Yes, but expect to be less accurate at first. Keep loads conservative and rely on technique as your guide.

Last updated September 2026. General education, not medical advice or a personalised prescription. Stop and seek qualified advice if you have sharp, increasing or persistent pain, or a health condition that may affect exercise.

Keep exploring

Research behind the advice

About the author

Nathan Gee is Peaksted’s founder: a sport scientist (BSc Sports Science) with a strength and conditioning background and eight years of coaching experience, focused on hiking and trekking performance. Meet the Peaksted team.