Reps in reserve calculator
Training two reps short of failure gets most of the benefit with less fatigue. Here is the weight that should leave about that many reps in reserve.
Your details
8 reps with 2 in reserve
75 kg
75% of 100 kg
- 8 reps, 0 in reserve (RPE 10)80 kg
- 8 reps, 1 in reserve (RPE 9)77.5 kg
- 8 reps, 2 in reserve (RPE 8)75 kg
- 8 reps, 3 in reserve (RPE 7)72.5 kg
- 8 reps, 4 in reserve (RPE 6)72.5 kg
- As RPE8 on the reps in reserve scale (Zourdos 2016)
- FormulaEpley: 8 + 2 = 10 reps to failure, 75.0% of your max
- For muscle size2 in reserve is close enough to failure for growth (Robinson 2024)
Most of the benefit of a set comes from the last few hard reps, so 1 to 3 in reserve suits most training. Failure every set mostly adds fatigue.
Sharp pain, a pop, or pain that lingers after a session is a reason to stop and see a GP or physio. Chest pain or feeling faint while lifting: stop, and call 999 if it does not pass.
The working
8 reps, 2 in reserve, 100 kg max
8 reps plus 2 in reserve behaves like 10 reps to failure: 1 ÷ (1 + 10 ÷ 30) = 75%, so load 75 kg. With nothing in reserve it would be 80 kg; with 4 in reserve, 72.5 kg.
2 in reserve is RPE 8 on the Zourdos scale. At 10 reps to failure Epley and Brzycki agree: (37 − 10) ÷ 36 = 75%. With nothing in reserve (8 reps) Brzycki says 80.6% against Epley's 78.9%. For strength, a 2024 meta regression found gains were similar across a wide range of reps in reserve; for muscle size, sets ending nearer failure did better.
Why stop short
Most of the gain, less of the cost
Research comparing failure with stopping a couple of reps short finds similar muscle growth, with less fatigue to carry into the next session.
Picking reserve
A rough guide
| Reps in reserve | Good for |
|---|---|
| 0 to 1 | last set of an isolation move |
| 1 to 3 | most working sets |
| 3 to 4 | technique work and deloads |
Read with care
What this cannot tell you
- Your real reserveOnly the bar tells you; adjust next set if it was easier or harder.
- FatigueLater sets drift towards failure at the same weight.
- PainReserve is about effort, never about pushing through pain.
Questions
Common questions
What does 2 RIR mean?
Stopping with about two more good reps possible.
Is training to failure necessary?
No. Stopping 1 to 3 reps short works about as well for most people.
How is the weight worked out?
Reps plus reserve are fed into the Epley formula (or Brzycki, if you pick it) as reps to failure.
Sources
- Zourdos MC et al. A resistance training specific RPE scale measuring repetitions in reserve. J Strength Cond Res 2016
- LeSuer DA et al. The accuracy of prediction equations for estimating 1-RM performance in the bench press, squat and deadlift. J Strength Cond Res 1997;11(4):211-3
- Schoenfeld BJ, Ogborn D, Krieger JW. Dose response of weekly set volume and muscle growth. J Sports Sci 2017
- Brzycki M. Strength testing: predicting a one rep max from reps to fatigue. JOPERD 1993
- Robinson ZP et al. Dose response between estimated proximity to failure, strength gain and muscle hypertrophy. Sports Med 2024
Last checked 21 October 2026. Spotted something wrong? Tell us and we will fix it.
Before you push on
New to exercise, or got a heart, lung or joint condition? Have a word with your GP or practice nurse first. Stop and get help if you feel chest pain, faintness or unusual breathlessness, and call 999 if it is severe.
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