Understanding RPE: Rate of Perceived Exertion Explained

What Is RPE and Where Did It Come From?

Rate of Perceived Exertion, or RPE, is a subjective scale used to measure how hard a set or exercise feels relative to your maximum effort. In the context of resistance training, the most widely used version is the modified Borg CR-10 scale, adapted for strength training by powerlifting coach Mike Tuchscherer and further popularized by researchers and coaches like Eric Helms.

The original Borg RPE scale (6 to 20) was developed in the 1960s for cardiovascular exercise, correlating roughly with heart rate. The resistance training adaptation uses a 1 to 10 scale, where each number corresponds to how many reps you could still perform before reaching muscular failure. This makes it intuitive and directly applicable to set-by-set training decisions.

The RPE Scale for Resistance Training

Here is how the 1 to 10 RPE scale maps to effort level and reps in reserve (RIR):

• RPE 10: Maximum effort. No additional reps could be performed. This is true muscular failure.
• RPE 9.5: Could maybe do one more rep, but not confident. Grinding territory.
• RPE 9: One rep left in the tank (1 RIR). Very hard but controlled.
• RPE 8.5: Definitely one more rep, possibly two.
• RPE 8: Two reps left in reserve (2 RIR). Challenging but strong.
• RPE 7: Three reps in reserve (3 RIR). Moderate difficulty, good bar speed.
• RPE 6: Four reps in reserve (4 RIR). Light to moderate. Warm-up territory for work sets.
• RPE 5 and below: Light effort. Typically used for warm-ups, technique work, or active recovery.

Most productive training for strength and hypertrophy occurs in the RPE 6 to 9 range, with the majority of working sets falling between RPE 7 and 9. Training below RPE 6 generally does not provide sufficient mechanical tension to drive adaptation, while consistently hitting RPE 10 accumulates excessive fatigue and increases injury risk.

RPE vs. Percentage-Based Training

Traditional percentage-based programs prescribe loads as a percentage of your one-rep max (1RM). For example, "3 sets of 5 at 82% of 1RM." This approach works, but it has a fundamental limitation: it assumes your capacity is constant from session to session. It is not.

Your true daily max fluctuates based on sleep quality, nutrition, stress, time of day, accumulated fatigue from previous sessions, and dozens of other factors. On a great day, 82% might feel like RPE 7. On a bad day, the same weight might feel like RPE 9. Percentage-based programs cannot account for this variability. You either undershoot on good days (leaving gains on the table) or overshoot on bad days (accumulating unnecessary fatigue or risking injury).

RPE-based training solves this problem through autoregulation. Instead of prescribing a fixed weight, the program prescribes an effort level. "3 sets of 5 at RPE 8" means you select a weight that leaves two reps in reserve for each set. On a strong day, that might be 185 kg. On a rough day, it might be 175 kg. Either way, the training stimulus is appropriately matched to your current capacity.

This does not mean percentage-based training is bad. For beginners, fixed percentages provide clear, simple guidelines that remove guesswork. But as you gain experience and your ability to assess effort improves, incorporating RPE adds a powerful layer of individualization to your training.

How to Calibrate Your RPE

The most common criticism of RPE is that it is subjective. And that is true. But subjectivity is a feature, not a bug, because your body is the ultimate authority on how hard something actually is. The challenge is learning to accurately assess your own effort. Here is how to develop that skill.

Start with Anchor Points

The easiest RPE values to learn are the extremes. You know what RPE 10 feels like: it is an all-out, grind-it-out, could-not-possibly-do-another-rep set. You know what RPE 5 feels like: light, almost easy, clearly a warm-up. Start by identifying those anchor points, and then build your awareness of the middle range over time.

Use Post-Set Assessment

After each working set, ask yourself: "How many more reps could I have done with good technique?" Be honest. Write down both the weight and the RPE in your training log. Over weeks, you will develop a dataset that connects specific loads, rep counts, and RPE values. This log becomes your personal calibration tool.

Periodically Validate with AMRAP Sets

An AMRAP (As Many Reps As Possible) set is the most direct way to test your RPE accuracy. If you have been logging your top set at 100 kg for 5 reps at RPE 8 (meaning you estimated 2 reps in reserve), occasionally take that same weight to failure. If you get 7 reps, your calibration is accurate. If you get 9 reps, you have been underestimating your capacity and your RPE assessments need adjustment.

Do this sparingly, once every few weeks per major lift, because training to true failure regularly is fatiguing. But these periodic checks are invaluable for refining your internal gauge.

Film Your Sets

Video review is one of the most effective calibration tools available. Bar speed is strongly correlated with proximity to failure. When you review footage, you can see whether the last rep was grinding (RPE 9 to 10) or still moving with reasonable speed (RPE 7 to 8). Over time, you learn to associate specific bar speed and rep quality with specific RPE values in real time.

Using RPE for Autoregulation

Autoregulation means adjusting your training in real time based on your current performance rather than blindly following a predetermined plan. RPE is the primary tool for autoregulation, and here are the most common ways to apply it.

Top Set and Backoff

Work up to a top set at a prescribed RPE, then perform backoff sets at a reduced percentage of that top set weight. For example: "Work up to a set of 3 at RPE 8, then do 3 sets of 3 at 90% of that weight." The top set self-selects based on how you feel that day, and the backoff sets scale proportionally.

Load Adjustment Within a Session

If your program calls for 4 sets of 6 at RPE 8, start with your best estimate of the appropriate weight. If the first set is RPE 7, add weight for the next set. If it comes in at RPE 9, reduce the weight. The goal is to keep each set within the prescribed RPE range rather than stubbornly sticking with a weight that is too heavy or too light.

Fatigue Stops

Some programs prescribe a fatigue threshold rather than a fixed number of sets. For example: "Perform sets of 5 at a given weight until RPE reaches 9, then stop." On a good day, that might be 6 sets. On a fatigued day, it might be 3. This approach automatically adjusts volume to your recovery state.

RPE for Different Exercises

Not all exercises are equally easy to rate with RPE. Understanding these differences will improve your accuracy.

Compound Barbell Lifts (Easiest to Rate)

Squats, bench press, deadlifts, and overhead press are the most RPE-friendly exercises. They involve large muscle groups, produce clear sensations of effort, and have obvious bar speed cues. Most people can accurately rate these within 0.5 RPE after a few months of practice.

Machine and Isolation Exercises (Moderate Difficulty)

Exercises like leg press, cable rows, and lateral raises are moderately easy to rate. The challenge is that isolation movements can reach local muscular failure (the target muscle gives out) while the overall systemic effort feels lower. Rate based on the target muscle, not overall fatigue.

High-Rep and Metabolic Work (Hardest to Rate)

Sets of 15 or more reps, especially for exercises like lunges, leg extensions, or high-rep rows, produce intense metabolic discomfort (the burn) that can distort RPE perception. A set might feel like RPE 10 because of the burn, but you could actually grind out several more reps if you tolerated the discomfort. For high-rep work, focus specifically on muscular failure rather than cardiovascular or metabolic distress.

Common RPE Calibration Mistakes

• Ego inflation: Rating sets lower than they actually were to feel stronger. If you are consistently rating sets at RPE 7 but your technique is breaking down, you are probably closer to RPE 9. Be brutally honest with yourself.
• Confusing cardiovascular fatigue with muscular effort: Being out of breath does not mean you are close to muscular failure. A set of heavy squats might leave you gasping at RPE 7. Learn to distinguish between systemic fatigue and actual proximity to failure.
• Not accounting for technical breakdown: RPE should be rated based on technically sound reps. If you could grind out two more reps but only with significant form breakdown, that is not truly RPE 8. Rate based on quality reps, not survival reps.
• Expecting perfection immediately: RPE calibration is a skill that develops over months, not days. Most lifters are within plus or minus 1 RPE when they start and refine to within plus or minus 0.5 after several months of deliberate practice. Be patient with the process.
• Only using RPE for main lifts: While compound lifts are easiest to rate, practicing RPE on accessory work builds overall body awareness and makes your main lift ratings more accurate over time.

Key Takeaways

RPE-based training is not about abandoning structure or winging it in the gym. It is about adding a layer of intelligent responsiveness to a well-designed program. Your body does not perform identically every day, and your training should reflect that reality. Learn the scale, practice honest self-assessment, validate your ratings periodically, and use RPE as a tool to train harder on your best days and smarter on your worst ones. Combined with solid programming and consistent logging, RPE-based autoregulation is one of the most effective strategies for long-term, sustainable progress.