RPE calculator

What RPE and RIR mean in training

RPE, rate of perceived exertion, is a 1 to 10 scale for how hard a set felt, adapted from general exercise science exertion scales into a version specific to resistance training. An RPE of 10 means you could not have done another rep, an RPE of 8 means you had about two reps left in the tank.

RIR, reps in reserve, is the same idea stated as a number of reps rather than a feeling: RIR is simply 10 minus your RPE. An RPE 8 set and a 2 RIR set describe the same effort, and most lifters find RIR easier to judge than a 1 to 10 feeling when they are new to autoregulation.

Where the scale comes from

General exertion scales for exercise go back decades, but the version behind this calculator is specific to resistance training and reps in reserve, developed and validated for the barbell lifts through research published in the mid 2010s. It replaced older, more subjective 1 to 10 scales borrowed from cardio training, which never mapped cleanly onto a set of squats or deadlifts.

Half-point RPE

Half-point ratings, RPE 7.5 or 8.5, are standard practice, not an approximation of the whole numbers either side. They exist because the gap between, say, two reps in reserve and one rep in reserve is a real and meaningful difference in load, and forcing every set into a whole number throws that precision away.

How the calculator turns RPE into a percentage

The calculator looks up your reps and RPE in the reps-in-reserve percentage chart used in autoregulation practice, then divides your lifted weight by that percentage to get an estimated one-rep max. To find a load for a different target RPE, it looks up the new percentage for the same rep count and multiplies it back against your estimated max.

A worked example

Say you lift 100 kg for 5 reps at RPE 8. The chart says 5 reps at RPE 8 is about 81 percent of 1RM, so your estimated max is 100 divided by 0.81, roughly 123 kg. If you then want a load for 5 reps at RPE 9, the chart gives about 84 percent, so 123 times 0.84 is roughly 103.7 kg.

The calculator rounds the final load to the nearest plate you can realistically load, 2.5 kg or 5 lb, since a chart output of 103.7 kg is not a weight anyone can put on a bar. Everything upstream of that last step keeps its full precision so the rounding never compounds.

Why RPE-based percentages instead of a fixed 1RM test

A true 1RM test needs a near-maximal single, real fatigue and, ideally, a spotter, and the number it gives you is only accurate for that one day. Formula-based estimators like the ones behind the one-rep-max calculator, Epley or Brzycki among them, avoid the max attempt but still assume a fixed relationship between reps and percentage that does not account for how ready you are that day.

RPE folds daily readiness into the number itself. Sleep, stress and accumulated fatigue all change what 90 percent of your max actually feels like on a given day, and rating effort lets your training load adjust to that automatically instead of chasing a fixed percentage regardless of how the bar moved.

Neither approach is wrong, they answer different questions. A fixed percentage plan is easier to write and easier to follow blindly, which suits a lifter who wants a simple number to hit. An RPE-based plan asks more of the lifter, honest self-assessment, but rewards that with a load that tracks how the training is actually going, week to week, rather than what a spreadsheet assumed months in advance.

RPE to percentage of 1RM chart

This is an approximation drawn from published RPE and reps-in-reserve research and widely used autoregulation practice, not a lab measurement of any one lifter. Five reps is the most common training range, and it is highlighted below.

Reading the chart is straightforward once you have the shape of it: move down a column and the percentage drops as reps increase, at a fixed RPE, since more reps at the same effort level means a lighter weight. Move across a row and the percentage drops as RPE drops, at a fixed rep count, since leaving more reps in reserve also means a lighter weight. The calculator does both lookups automatically, but seeing the pattern helps you sanity check any number it gives you.

How to use RPE in your training

Rate the set honestly right after your last rep, before you have decided how you want to feel about it. It takes several weeks of practice to calibrate an RPE rating to how your body actually performs, so early on treat the number as a rough guide rather than a precise instrument.

Use it to decide the next session: if last week's target RPE 8 set felt like a 7, you have room to add weight. If it felt like a 9, hold or drop slightly. Where you have access to bar speed data, use it alongside RPE rather than instead of it, since velocity loss is a more objective check on the same underlying fatigue.

Calibrating your own scale

Filming your working sets and reviewing them afterwards is one of the fastest ways to close the gap between how a set felt and how it actually looked. Most lifters are surprised the first few times, a set that felt like a grinding RPE 9 often still had visibly crisp bar speed, or the reverse, a set that felt manageable was already slowing down noticeably by the last rep. Reviewing footage over a few weeks, not just once, is what actually moves the needle on accuracy.

RIR or RPE, does it matter which you use

No, they map to the same chart and describe the same effort. Some coaches prefer RIR with newer lifters because "how many more reps could you do" is a more concrete question than "rate this 1 to 10", but experienced lifters often move to RPE because it captures technical breakdown and bar speed, not just a raw rep count.

Use whichever your athlete finds easier to answer consistently. Consistency matters more than which label you use, since the number only helps if it means the same thing week to week.

In practice, many coaches introduce RIR first, because counting down from a known stopping point is a more concrete skill than judging a feeling on an abstract 1 to 10 scale, and only switch the athlete's language to RPE once that judgement is reliable. Either way, write down which convention a programme uses at the top of the plan, since mixing the two mid block is how a client ends up guessing at what a number means.

RPE versus velocity-based training

Velocity-based training, measuring how fast the bar moves on each rep with a linear position transducer or a phone-based app, is the more objective cousin of RPE. Where RPE asks a lifter to rate how a set felt, VBT measures a physical quantity directly, bar speed, and uses a drop in that speed across a set as the signal that fatigue is accumulating, rather than relying on self-report.

The two are not competitors so much as different instruments for the same underlying job. VBT needs hardware, a device on the bar or a phone propped where it can track the path, and produces a number a lifter cannot argue with, useful for beginners who have not yet learned to rate effort accurately, or for a coach who wants an objective check on a lifter who tends to underrate or overrate sets. RPE needs nothing but attention and practice, travels anywhere, and captures things velocity alone does not, like how a lift felt technically even when the bar speed held up.

Many coaches use both where equipment allows: RPE as the primary daily tool, since it costs nothing and scales to every session, and velocity readings as a periodic check, especially early in a lifter's training when their RPE calibration is still unreliable, or on a big test day where an objective number matters more than usual.

Cost is the practical reason RPE stays the default for most lifters and most gyms. A basic velocity tracker still runs to real money, and a phone-based app needs a consistent camera angle and a flat, well-lit setup to give comparable readings session to session, which is more friction than most training environments can offer for every set of every session. RPE asks for nothing beyond a moment of honest self-assessment after the bar stops moving, which is why it remains the more widely used tool even among lifters who also own a velocity device.

Using RPE for accessory and hypertrophy work

The reps and RPE chart above is built from compound barbell lifts, where a clean technical failure point makes the top of a set easy to identify. Accessory and hypertrophy work, higher-rep isolation sets on a leg curl, a lateral raise or a cable row, does not have the same clean failure point, so the same chart applies more loosely there than it does to a squat or a deadlift.

For hypertrophy training, most programmes call for RPE 7 to 9 across sets of 8 to 15 reps, deliberately staying a few reps back from failure on most working sets and reserving true failure, RPE 10, for the last set of an exercise if at all. The reasoning is the same as it is for a heavy compound lift: rating effort lets the load adjust to how ready the muscle actually is that day, rather than chasing a fixed weight regardless of accumulated fatigue from earlier exercises in the session.

The chart is also less useful the further into a session you get. RPE on the fourth exercise of a session is being rated against a body that is already fatigued from the first three, not against a fresh 1RM, so an RPE 8 leg extension after a heavy squat session is a genuinely different physical event from an RPE 8 leg extension on a fresh day. Track the weight and reps alongside the RPE rather than relying on RPE alone late in a session.

For most accessory work, a simpler practical rule beats the chart entirely: pick a weight, do it for the prescribed rep range, and add load once the top of that range feels like an RPE 7 or below two sessions in a row. This calculator is still useful here for the estimated 1RM it gives you, a rough ceiling to sanity check a jump in weight against, even when the exact percentage table stops applying cleanly.

Common RPE mistakes

Overestimating effort. Calling a set that had three or four reps left an RPE 8 or 9 inflates every estimate the chart gives you afterwards.

Rating before the bar slows down. RPE should reflect how the whole set felt, including the grind at the end, not just how the first rep or two moved.

Treating isolation work like a compound lift. Single-joint exercises rarely have the same clean relationship between reps, RPE and percentage as a squat or deadlift, since technical breakdown looks different.

Chasing the chart number instead of the goal. RPE is a tool for picking a sensible load, not a target to hit for its own sake every single set, and treating every set as a test of exactly how heavy you can make it is a fast route to burnout.

Never recalibrating. As work capacity and technique improve, the same RPE at the same reps can correspond to a genuinely heavier weight than it did months earlier.

Using RPE and hard percentage targets at the same time without a rule for which wins. If a plan says both 85 percent and RPE 8 for the same set, decide in advance which one the athlete should follow when they disagree, otherwise every set becomes a negotiation.

How coaches use an RPE calculator

Autoregulated programming, prescribing a target RPE instead of a fixed percentage, lets a plan flex around a client's day-to-day readiness without a coach having to rewrite the week every time life gets in the way.

It is particularly useful for clients training independently between in-person sessions, where a coach cannot see the bar speed or the grind on the last rep directly and has to rely on what the client reports afterwards.

Scraler captures a client's logged RPE per set alongside their workouts, so a coach can see effort trending up or down across weeks, and pull it into the same check-ins where sleep, stress and soreness are already tracked, rather than piecing the picture together from separate messages.