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RPE calculator — RPE to %1RM and 1RM.
RPE (rating of perceived exertion) rates how hard a set felt on a 6-to-10 scale, where RIR (reps in reserve) equals 10 minus RPE. This calculator uses the Reactive Training Systems / Zourdos RPE chart to convert your weight, reps and RPE into an estimated 1RM, the exact %1RM, and RIR — then builds a backoff table. Enter a set below; it updates instantly, no signup.
Your backoff table
The weight to load for your rep count at each RPE, based on the estimated 1RM above. Use it to pick your top set and backoff sets by feel.
The RPE chart.
No black box — the Reactive Training Systems chart popularised by Dr. Mike Zourdos's RIR-based RPE research.
RIR = 10 − RPE RPE 8 means 2 reps in reserve. RPE and RIR describe the same thing from opposite ends.
% = chart[RPE][reps] Look up the RPE × reps cell. Example: RPE 8 × 5 ≈ 81% of 1RM on the RTS chart.
1RM = weight ÷ (% ÷ 100) Divide the weight by the percentage. 100 kg at 81% ≈ 123 kg estimated max.
Source: the Reactive Training Systems RPE chart, the load-percentage table underpinning the RIR-based RPE scale validated by Zourdos et al. (2016). Most reliable at 1–6 reps; accuracy falls at higher reps and for lifters new to gauging reps in reserve.
RPE ↔ RIR at a glance
| RPE | Reps in reserve | What it feels like |
|---|---|---|
| 10 | 0 | No reps left — a true grinder |
| 9.5 | 0–1 | Maybe one more, maybe not |
| 9 | 1 | One clean rep left in the tank |
| 8 | 2 | Two reps left — a hard working set |
| 7 | 3 | Three left — moderate, still crisp |
| 6 | 4+ | Light; speed and technique work |
Related strength calculators.
Cross-check your max, then let the tracker program every set for you.
RPE questions.
What is RPE in lifting?
RPE, or rating of perceived exertion, is a 6-to-10 scale for how hard a set felt. An RPE of 10 means no reps were left, RPE 9 means one rep in reserve, RPE 8 means two, and so on. It lets you auto-regulate load day to day: on a strong day the same RPE allows more weight, on a tired day less.
How do you convert RPE to percentage of 1RM?
RPE converts to a percentage of 1RM through a lookup chart that pairs each RPE with a rep count. For example, RPE 8 for 5 reps is about 81% of 1RM on the Reactive Training Systems chart. This calculator reads that chart, then divides your weight by the percentage to back out your estimated one rep max.
What is the difference between RPE and RIR?
RIR, reps in reserve, is simply 10 minus your RPE. RPE 8 equals 2 reps in reserve, RPE 9 equals 1, and RPE 10 equals 0. Many lifters find counting reps in reserve more intuitive than rating exertion, but the two describe the same thing and convert directly.
How accurate is estimating 1RM from RPE?
Estimating 1RM from RPE is reasonably accurate for experienced lifters who can gauge reps in reserve within one, usually landing within about 5% of a tested max in the 1-to-6 rep range. Accuracy falls for novices, for high-rep sets, and when RPE is misjudged, so treat the estimate as a training guide, not a competition number.
What RPE should I train at?
Most hypertrophy work sits at RPE 7 to 9, hard enough to drive growth while leaving a rep or two in reserve to manage fatigue. Strength and peaking work climbs to RPE 8 to 10 on top singles and doubles. Deloads and technique days stay at RPE 6 to 7. Auto-regulate by feel rather than chasing a fixed percentage.
Log RPE. Auto-regulate.
Free in your browser — Nishaana turns your per-set RPE into the exact weight to load next session, so progression follows how you actually feel.
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