Formula, in Strength Training

RPE to Percentage Formula (Tuchscherer)

RPE (rating of perceived exertion) on the reps-in-reserve scale says how many more reps you could have done: RPE 10 is none, RPE 8 is two. Mike Tuchscherer's RTS chart converts reps and RPE to a share of 1RM, so 5 reps at RPE 8 sits at the same load as 7 reps to failure: 81.1% of 1RM. Each RPE point is worth roughly 2.5% at a given rep count.

3 variables. Published May 14, 2026. Updated Oct 19, 2026. By AI Fit Hub.

Education, not medical advice. The result comes only from the published formula and your inputs. How we check our formulas.

Formula

%1RM = chart(reps + (10 − RPE))
   a set at RPE r for n reps uses the RPE-10 load for n + (10 − r) reps
   RPE-10 column (reps 1–12): 100, 95.5, 92.2, 89.2, 86.3, 83.7, 81.1, 78.6, 76.2, 73.9, 70.7, 68.0%
load = %1RM × 1RM

Variables

%1RM

Share of 1RM

The load as a percent of your one-rep max: 81.1% of a 180 kg max is 146 kg.

RPE

Rating of perceived exertion

On the reps-in-reserve scale: RPE 10 = no reps left, RPE 9 = one, RPE 8 = two, RPE 7 = three, with half points in between (Helms 2016).

reps

Reps in the set

Needed because the share of 1RM falls as reps rise: 1 rep at RPE 10 is 100%, 3 reps 92.2%, 8 reps 78.6%.

Step by step

1

Take the programmed reps and RPE.

5 reps at RPE 8 on the squat.
2

Add the reps in reserve to the reps, and read the RPE-10 percentage for that total.

5 + 2 = 7 reps → 81.1% of 1RM.
3

Multiply by your 1RM and round to loadable plates.

180 × 0.811 = 146 kg → 145 kg on standard plates.
4

If the set lands at a different RPE, re-estimate the 1RM from what happened instead of guessing a correction.

146 kg × 5 at RPE 9 is the 83.7% cell: 146 / 0.837 = 174 kg estimated 1RM for the day.

Worked example

A powerlifter with a 180 kg squat runs a 5-rep set at RPE 8

Current 1RM

180 kg

Reps

RPE

5 reps + 2 in reserve = 7-rep max → 81.1% (RTS chart) 180 × 0.811 = 146 kg

5 reps at RPE 8 is 81.1% of 1RM: 146 kg for a 180 kg squat, or 145 kg on standard plates.

Common variations

Reps in reserve: the RIR-based RPE scale used here anchors each RPE number to reps left in the tank, which Helms and colleagues proposed for resistance training (Helms 2016).

Brzycki: %1RM = 1 / (1.0278 − 0.0278 × reps) estimates the load for a set to failure only, so it has no RPE input.

Velocity-based training: bar speed on the concentric phase tracks the share of 1RM closely, so a velocity tracker can replace the effort rating (González-Badillo & Sánchez-Medina 2010).

Run the numbers next

Strength One-Rep Max Calculator
Estimate one-rep max with Epley, Brzycki, and Lombardi formulas.
Strength Strength Standards Calculator
Rank your lifts from Beginner to Elite based on bodyweight ratios.
Strength Velocity-Based 1RM Estimator
Estimate one-rep max from concentric bar velocity using published load-velocity profiles.

Sources

Tuchscherer M (2008). The Reactive Training Manual. , Reactive Training Systems — the RPE chart
Helms ER et al. (2016). Application of the repetitions in reserve-based rating of perceived exertion scale for resistance training. , Strength and Conditioning Journal — the RIR-based RPE scale
González-Badillo JJ & Sánchez-Medina L (2010). Movement velocity as a measure of loading intensity in resistance training. , International Journal of Sports Medicine — velocity and %1RM