RIR calculator.
Start from reps in reserve. Enter the reps you did and how many you left in the tank, and this RIR calculator reads back the equivalent RPE (RPE = 10 - RIR), the percentage of your one-rep max that effort represents, and the exact weight to load. Zero reps in reserve is failure at RPE 10; each rep you leave takes the effort - and the load - down a step.
what do you want to find?
Enter the reps you did and how many you left in reserve. Add the weight you used (optional) and the calculator estimates your one-rep max too.
percentage of 1RM
-- %
Enter your reps and reps in reserve, then press Calculate.
Estimates only - the reps-to-failure chart is a guide, not a measured max. Reported reps in reserve drifts by lifter and by lift, so load from how the set actually moves and warm up before heavy work.
the short answer
Reps in reserve (RIR) is how many reps you leave in the tank. It converts straight to RPE: RPE = 10 - RIR, so 2 RIR is RPE 8 and 0 RIR is failure at RPE 10. For the load, add reps and RIR to find the reps-to-failure, then read the %1RM - 8 reps @ 2 RIR is a 10-rep-equivalent effort, about 74% of your max. Then working weight = 1RM x (%1RM / 100), or estimate the max as 1RM = weight / (%1RM / 100).
RIR to RPE conversion.
| Reps in reserve (RIR) | Equivalent RPE | What it means |
|---|---|---|
| 0 | 10 | True failure - nothing left in the tank |
| 1 | 9 | Could have done 1 more rep |
| 2 | 8 | Could have done 2 more reps |
| 3 | 7 | Could have done 3 more reps |
| 4 | 6 | Could have done 4 more reps |
| 5 | 5 | Could have done 5 more reps |
One rule covers the whole scale: RPE = 10 - RIR. Prefer to program in effort numbers instead? The RPE calculator is the same math read from the RPE end.
RIR chart: reps and reps in reserve to %1RM.
| Reps \ RIR | 0 | 1 | 2 | 3 | 4 | 5 |
|---|---|---|---|---|---|---|
| 1 | 100% | 96% | 92% | 89% | 86% | 84% |
| 2 | 96% | 92% | 89% | 86% | 84% | 81% |
| 3 | 92% | 89% | 86% | 84% | 81% | 79% |
| 4 | 89% | 86% | 84% | 81% | 79% | 76% |
| 5 | 86% | 84% | 81% | 79% | 76% | 74% |
| 6 | 84% | 81% | 79% | 76% | 74% | 71% |
| 8 | 79% | 76% | 74% | 71% | 68% | 65% |
| 10 | 74% | 71% | 68% | 65% | 63% | 60% |
Read across: each cell is the percentage of your 1RM you would expect to lift for that many reps at that RIR. The load tracks proximity to failure, so 0 reps in reserve is always the heaviest column for a given rep count.
What reps in reserve is and how the calculator uses it.
Reps in reserve (RIR) is the number of reps you could still have completed with good form when you ended a set. Stop a set of 8 that had 2 clean reps left and you trained at 2 RIR. It is an intensity cue: rather than chase a fixed percentage every day, you leave a set number of reps in the tank and let the honest weight for that reserve find itself. RIR maps one-to-one onto RPE through RPE = 10 - RIR, so 0 in reserve is a max-effort set at RPE 10 and 4 in reserve is RPE 6.
To turn a reserve into a load, the calculator adds your reps to your reps in reserve to get the total reps you would have managed to true failure, then reads the percentage of 1RM off the standard reps-to-failure chart. Eight reps with 2 in reserve is a 10-rep-to-failure effort, about 74% of your max; 5 reps with 2 in reserve is a 7-rep effort, about 81%. Notice the percentage follows proximity to failure, not the raw rep count. The two core operations are:
Estimated 1RM = weight / (%1RM / 100)
In RPE & %1RM mode, enter reps and reps in reserve to read the equivalent RPE and the percentage; add the weight you actually used and it back-solves your estimated one-rep max. In Working weight mode, enter your 1RM (tested or estimated) plus the reps and reserve you want to train at, and it returns the precise weight to load. Pounds are converted to kilograms internally, so the math holds in either unit, and switching units converts the displayed weight so the load stays physically the same. It uses the same chart as our RPE calculator, so the two never disagree.
RIR vs RPE: when each cue works better.
RIR and RPE describe the same intensity from opposite ends. RIR counts the reps you have left; RPE rates how hard the set felt on a 1 to 10 scale. Because RPE = 10 - RIR, they resolve to the same percentage and the same weight, so the choice between them is really a coaching decision about which number the client reports most accurately.
Reps in reserve is often the easier cue for beginners. Counting concrete reps left is more tangible than grading abstract effort, and a new lifter can usually answer the question in front of the mirror: could I have done 2 more good reps here? RPE asks them to translate that feeling into a number they have not yet internalised, which is why early RIR reports are more consistent than early RPE reports. RPE tends to win once a lifter has real experience, because one effort number reads faster than a subtraction and captures grind on very heavy singles and doubles, where reps-left estimates get thin.
A practical path is to teach RIR first, let the client build a feel for proximity to failure, and only move them to RPE once the scale is second nature. Prescribe in whichever cue the client speaks, and read it back through the tool: this RIR calculator and the RPE calculator land on identical loads, so you can mix cues across a roster without the numbers fighting each other.
How coaches program with RIR.
Most coaches anchor hypertrophy blocks around 2 to 3 reps in reserve on the working sets. That range lets a client accumulate a lot of hard, effective volume without the recovery cost of taking every set to failure, and it leaves room to add reps or load week to week as the block progresses. Strength work on the main lifts usually sits a little closer to the limit, often 1 to 3 in reserve, with the heaviest singles and doubles nearer 1. Early in a block, when grooving a new movement, or on a deload, keeping 3 to 4 in reserve keeps quality high while fatigue is low. These are mainstream ranges, not precise prescriptions - treat them as starting points and adjust to the athlete.
RIR pairs naturally with volume planning. Once you know the reserve you are prescribing, the sets and reps at that effort are what actually drive the weekly hard-set count, so it is worth checking the total against sensible landmarks with the weekly training volume calculator. To set the loads those sets run at, estimate a max first with the one-rep max calculator, then read the working weight for the prescribed reps and reserve here, and build the ramp up to it with the warm-up set calculator.
Running reps-and-reserve to load math for every lift and every client by hand gets old fast. Coachway lets coaches program by RIR, RPE or percentage for each client - prescribe the reserve, and the working weights and check-in cues live inside a branded app clients actually open. It is the same chart as this free tool, applied across a full client list instead of one set at a time.
Why client-reported RIR drifts, and how to calibrate it.
The weak point of RIR is that it depends on the client reading their own effort, and less experienced lifters tend to get it wrong in a predictable direction: they stop too early and overestimate how hard the set was. A client who reports 2 in reserve often had 4 or 5 genuinely left, which means the prescribed effort - and the load - lands lighter than intended. Accuracy improves with training age, and it sharpens the closer a set gets to failure, where the reps actually start to slow and the reserve becomes obvious. Far from failure, the estimate is mostly a guess.
Calibrate it with the occasional AMRAP - an as-many-reps-as-possible set at a fixed load. Ask the client to predict their reps in reserve at the target rep count, then let them keep going to a hard, safe limit. The gap between the reps they thought they had left and the reps they actually completed is the correction: if they called 2 in reserve at rep 8 but reached 15, their scale needs recalibrating and future sets should push closer. Sprinkle these tests in every few weeks on lifts where an honest limit is safe, feed the result back into the reserve you prescribe, and the reported number tightens over time.
RIR calculator FAQ.
What is a RIR calculator and what does reps in reserve mean?
Reps in reserve (RIR) is how many more reps you could have done before hitting failure on a set. A RIR calculator turns your reps and RIR into the effort and load they represent: it converts RIR to RPE, reads the matching percentage of your one-rep max off the standard chart, and, if you enter a 1RM or a working weight, returns the weight to load. So a set of 8 with 2 reps in reserve means you stopped with 2 good reps left in the tank, an effort worth about 74% of your max.
How do I convert RIR to RPE?
RIR and RPE are the same scale read from opposite ends, so the conversion is one step: RPE = 10 - RIR. Zero reps in reserve is a true max effort, RPE 10. One rep in reserve is RPE 9, 2 in reserve is RPE 8, 3 in reserve is RPE 7, and so on down. Counting the reps you have left (RIR) and rating how hard the set felt (RPE) point at the same intensity from different angles, which is why the two calculators use one shared chart and never disagree.
How does RIR map to a percentage of my 1RM?
Add your reps to your reps in reserve to get the total reps you could have managed to failure, then read that number off the reps-to-failure chart. Five reps with 2 in reserve is a 7-rep-to-failure effort, about 81% of your max. Eight reps with 2 in reserve is a 10-rep effort, about 74%. The percentage tracks proximity to failure, not the raw rep count, which is why the same reps at a lower RIR always represents a heavier percentage.
RIR or RPE - which should I use with clients?
They resolve to the same load, so pick the cue the client reports most accurately. RIR tends to be easier for newer lifters because counting concrete reps left is more tangible than rating abstract effort on a 10-point scale. Experienced lifters often prefer RPE because a single effort number reads faster once the scale is internalised. Many coaches teach RIR first, then let the client graduate to RPE. If you prefer the effort-number framing, the sister tool is the RPE calculator.
How many reps in reserve should I program?
For most hypertrophy work, 2 to 3 reps in reserve on the majority of sets lets you accumulate hard, effective volume without the fatigue cost of training to failure every set. Strength work on the main lifts usually lives a little closer to the limit, often 1 to 3 in reserve, with heavier singles and doubles nearer 1. Early in a block or when grooving technique, keeping 3 to 4 in reserve is sensible, and failure is best saved for the occasional set, often on machines or isolation work where the risk is lower.
Why do clients report RIR wrong, and how do I fix it?
Less experienced lifters tend to stop too early and overestimate how hard the set was, calling it 2 in reserve when 4 or 5 were really there. Accuracy improves with training age and gets sharper the closer the set is to failure, where the reps genuinely start to slow. Calibrate it with the occasional AMRAP, an as-many-reps-as-possible set at a fixed load: compare the reps the client predicted they had left with the reps they actually hit, and recalibrate the cue from the gap.
This calculator gives estimates for general training use, not medical advice. The reps-to-failure chart is a guide - rate the reserve honestly, load from how the set actually moves, warm up thoroughly, and use a spotter near maximal weights.
Keep going: prefer effort numbers? Use the RPE calculator for the same math from the RPE end. Estimate a max with the one-rep max calculator, check your sets against the landmarks in the weekly training volume calculator, and build the ramp to your top set with the warm-up set calculator. Or browse every free coaching calculator.
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