RIR Calculator (Reps in Reserve)
Last updated: June 2026 · Free · No sign-up required
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What is RIR (Reps in Reserve)?
Reps in Reserve is the standard way lifters autoregulate effort: it counts how many clean reps you could still have performed when you ended a set. Stopping a set of 8 when you had two more in you is 2 RIR — equivalent to RPE 8. Tracking RIR lets you prescribe intensity without maxing out every week.
How the calculator works
- Enter the weight you lifted and the reps you completed.
- Select how many reps you had left in reserve.
- The tool adds those reps back and runs the Epley one-rep-max formula on the true effort, then converts your set into a percentage of 1RM and suggests loads for common rep/RIR targets.
Why train with RIR?
Research on proximity-to-failure shows most hypertrophy and strength benefits are captured between 0 and 3 RIR, while stopping short of failure reduces fatigue and lets you hold quality volume across a week. Estimating 1RM from a submaximal set also avoids the injury risk and recovery cost of true max testing.
Quick reference
| Set | RIR | Estimated 1RM | Set intensity |
|---|---|---|---|
| 100 kg × 8 | 2 | 133.3 kg | 75% (RPE 8) |
| 100 kg × 8 | 0 | 126.7 kg | 79% (RPE 10) |
| 225 lb × 5 | 3 | 285 lb | 79% (RPE 7) |
| 60 kg × 12 | 1 | 86 kg | 70% (RPE 9) |
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Interpretation guide
| RIR | RPE | Typical use |
|---|---|---|
| 0 | 10 | Testing, last set of a peak week |
| 1–2 | 8–9 | Main hypertrophy/strength work |
| 3–4 | 6–7 | Volume work, technique practice |
| 5+ | ≤5 | Warm-ups, deloads, speed work |
Formula & methodology
Formula: 1RM ≈ weight × (1 + (reps + RIR) ÷ 30) — Epley formula on the reps you could have done
- Enter the weight lifted and the reps you completed.
- Pick your RIR — how many clean reps you had left in the tank when you racked it.
- The tool adds RIR to your reps (the set was really an 8-rep effort at 10-rep strength if you stopped at 2 RIR) and runs the Epley 1RM formula.
- Use the suggested-load rows to pick weights for upcoming sets at common rep/RIR targets.
Worked example: 100 kg × 8 with 2 RIR → effective 10-rep max → 1RM ≈ 100 × (1 + 10/30) = 133.3 kg; the set was 75% of 1RM at RPE 8.