What percentage
did you really lift?
RPE turns how a set felt into how hard it actually was. Enter a set you did — weight, reps, and RPE — and get your estimated 1RM, then the exact weight to load for any target reps and RPE, straight from the RTS / Tuchscherer chart.
iPhone · iOS 17 +
Calculator
RPE → Percentage Calculator
The set you did
The set you want to hit
Your set sits at 81.1% of 1RM.
Target prescription
That target is 86.3% of your e1RM. Round to the nearest plate you can load.
Based on the Reactive Training Systems (RTS) chart popularized by Mike Tuchscherer. RPE values map to RIR (Reps In Reserve): RPE 10 = 0 reps left, RPE 8 = 2 reps left. The chart is a population average — your true percentages drift a little day to day, which is exactly why RPE autoregulates around them.
The science
How RPE, RIR and
percentages connect
RPE — Rate of Perceived Exertion — is a 1–10 reading of how hard a set was. In the gym it is anchored to RIR, Reps In Reserve: the number of clean reps you could still have done. The two are mirror images — RIR is just 10 − RPE.
- RPE 10 = 0 RIR — taken to failure, nothing left
- RPE 9 = 1 RIR · RPE 8 = 2 RIR · RPE 7 = 3 RIR
- Half points (9.5, 8.5…) cover the "maybe one more" feel
The link to percentages comes from a lookup chart. Because a near-maximal effort at a fixed rep count tends to land at a predictable fraction of your one-rep max, you can read the table both ways: a set you did implies an estimated 1RM (e1RM), and a target you want implies the weight to load.
The math:
- e1RM = weight ÷ (chart% ÷ 100)
- target weight = e1RM × (chart% ÷ 100)
The chart itself was popularized by Mike Tuchscherer through Reactive Training Systems (RTS), who brought autoregulated RPE into raw powerlifting. Its real power is that it adapts to you on the day: when 225 × 5 feels like an RPE 9 instead of the planned 8, the bar is telling you to take a little off — the program bends so you don't break.
Worked examples
Two real calculations, step by step
Scenario 1 — estimate a 1RM
You squatted 100 kg for 5 reps at RPE 8
Chart: 5 reps @ RPE 8 = 81.1% of 1RM
e1RM = 100 ÷ (81.1 ÷ 100)
= 123.3 kg estimated max
Scenario 2 — prescribe a target
Now load a triple at RPE 8 off that 123.3 kg max
Chart: 3 reps @ RPE 8 = 86.3% of 1RM
target = 123.3 × (86.3 ÷ 100)
≈ 106.4 kg — round to the bar
FAQ
Common questions
What is RPE in weightlifting?
RPE stands for Rate of Perceived Exertion — a 1–10 scale of how hard a set felt. In lifting it is read through reps in reserve: an RPE 10 set is taken to failure with nothing left, RPE 9 leaves about one rep, RPE 8 leaves two, and so on. It lets you push hard on good days and back off on bad ones without changing the program on paper.
How do RPE and RIR relate?
They are two ways of saying the same thing. RIR (Reps In Reserve) is simply 10 minus the RPE: RPE 10 = 0 RIR, RPE 9 = 1 RIR, RPE 8 = 2 RIR, RPE 7 = 3 RIR, RPE 6 = 4 RIR. Half-point RPEs (9.5, 8.5…) cover the in-between feel — RPE 9.5 means you maybe had one more rep, maybe not.
How does RPE convert to a percentage of 1RM?
Through a lookup chart. Mike Tuchscherer and Reactive Training Systems mapped each combination of reps and RPE to an expected percentage of your one-rep max — for example, 1 rep at RPE 10 is 100%, while 5 reps at RPE 8 is about 81%. This calculator reads that chart directly, then works backward to estimate your 1RM or forward to prescribe a target weight.
How accurate is an RPE-based 1RM estimate?
It is a well-validated estimate, not a tested max. Accuracy depends on how honestly you rate effort: beginners tend to under-rate RPE and overshoot their true 1RM. The estimate is most reliable in the 1–6 rep range at RPE 8 or higher, where the load-velocity relationship is tightest. Use it as a guide and let day-to-day RPE autoregulate the real load.
Who created the RPE chart?
The reps-and-RPE percentage chart was popularized by Mike Tuchscherer through Reactive Training Systems (RTS) in the early 2010s. He adapted the older Borg perceived-exertion scale into an autoregulated framework for raw powerlifting, and it has since become a standard tool in evidence-based strength programming.
Autoregulate for real
Log RPE on every set,
let the math follow.
A chart is a starting point. Zenith records the RPE of every working set, tracks your e1RM trend, and suggests next session's loads — so your program autoregulates without a spreadsheet.
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Marcus Chen
NSCA-CPT, MS Exercise Science · Reviewed June 2026