RPE to Percentage Chart (RIR to % of 1RM)

An effort rating and a percentage of maximum are two descriptions of the same set. This chart converts between them: given the reps you completed and how many you left in reserve, it tells you what share of your one rep max you were handling. Rate a set below to see it computed live.

What was actually measured

Three loads, and only three. The reps-in-reserve scale was studied on trained squatters rating sets at known percentages of a tested one rep max, and Helms and colleagues are explicit about which values that produced: single repetitions at 90% and 100% of 1RM, and a set of 8 repetitions at 70% of 1RM. Every other rep-and-percentage combination in the chart they published is, in their own words, an estimation around those anchors — and all of it comes from the barbell back squat.

Two of the three translate straight into the question this page answers:

• A single at 100% of 1RM is RPE 10, zero reps in reserve. A lift you cannot repeat is your maximum by definition, so that end of the scale is fixed rather than estimated.
• The set of 8 reps at 70% of 1RM was rated around 3 reps in reserve, with a standard deviation of 1.2 — two thirds of those lifters fell between 2 and 4 RIR. Counted as reps-to-failure, 70% of 1RM sat roughly eleven reps from failure for that group.

Their chart is published under a license that does not allow reproducing or reformatting it, so the table below is not that chart. It is our own arithmetic, checked against those measured points.

The chart, computed from the Epley formula

Add your reps in reserve to the reps you completed to get reps-to-failure, then invert Epley:

%1RM ≈ 100 ÷ (1 + reps to failure ÷ 30)

Reps completed	RIR 0 (RPE 10)	RIR 1 (RPE 9)	RIR 2 (RPE 8)	RIR 3 (RPE 7)
1	96.8% *	93.8%	90.9%	88.2%
3	90.9%	88.2%	85.7%	83.3%
5	85.7%	83.3%	81.1%	78.9%
8	78.9%	76.9%	75.0%	73.2%
10	75.0%	73.2%	71.4%	69.8%

* Use 100% for a single you cannot repeat — see the next section.

Every cell is an estimate from that one line, not a measurement, and the same line covers rep counts and ratings the table leaves out. Read a row across and the cost of stopping early shows up immediately: five reps at the edge of failure works out to 85.7% of max, the same five reps with three in the tank to 78.9%. Read a column down and you get the usual tradeoff between load and volume.

Where the estimate and the measurements part company

At the top of the scale the formula is simply wrong. For one rep to failure it returns 96.8%, because Epley keeps adding a per-repetition bonus where there is no repetition left to add. A rep you cannot repeat is your maximum: the measured value is 100%, and that is the one to use.

At the long end it reads slightly high. The formula and the NSCA load chart agree exactly at ten reps — both put a 10-rep max at 75% — but the squatters in the research were handling 70% of 1RM at about eleven reps from failure, where the formula says 73.2%. Between roughly eight and twelve reps, expect this estimate to sit two or three points above what a trained lifter actually does.

How much this varies between lifters

Enough that the chart is a concept, not a conversion tool. Among trained squatters performing 8 reps at 70% of maximum, ratings spanned 1 to 5 reps in reserve, with a standard deviation of 1.2. Roughly two thirds of them reported somewhere between 2 and 4. Individual differences in how many reps a given percentage allows are well documented, and day-to-day variation stacks on top.

The other chart, and how it differs

This page starts from effort: you finished a set, you know how much was left, and you want the percentage. The 1RM percentage chart starts from repetitions: you know how many reps a rep-max set holds, and you want the load to prescribe. One grades a set after the fact; the other plans one in advance.

For the estimated max these percentages apply to, use the RIR calculator; for what each rating means, the reps in reserve scale.

This content is informational and does not replace coaching.