RPE vs. RIR: Which Metric Should You Log?

The Scale

RPE(Rate of Perceived Exertion)

Origin: Powerlifting.

Pros: Accounts for how you feel that day.If you are sick, 225lbs might feel like RPE 9(usually RPE 7).It allows you to autoregulate down.

RIR(Reps in Reserve)

Origin: Bodybuilding.

Pros: Very intuitive. "I could have done 2 more."

Cons: Easy to lie to yourself.

The Accuracy Gap: Why You Lie to Yourself

Scientific studies show that novice lifters are terrible at estimating RPE.

They often report an RPE 9 when they actually had 5 + reps left.

The Fix: Take one set of a safe exercise(like a Leg Press) to absolute, shaking, mechanical failure.

Now you know what "10" feels like.

Use that as your North Star.If your RPE 8 doesn't feel like a brother to that RPE 10, you are sandbagging your sets.

Which to Use ?

• Strength / Low Reps: Use RPE.When grinding a heavy triple, it's hard to count "reps left."
• Hypertrophy / High Reps: Use RIR.On a set of 12, ask yourself: "If I offered you $1M, could you have done 2 more?"

RepLog supports both.Pick one and be consistent.

Autoregulation: Listening to the Body

The beauty of RPE / RIR is Autoregulation .

Static programs say: "Lift 225lbs for 5."

But what if you didn't sleep? What if you are stressed?

• Bad Day: 225lbs feels like RPE 10. Adjustment: Drop to 205lbs to hit RPE 8.
• Good Day: 225lbs feels like RPE 6. Adjustment: Add weight to 235lbs to hit RPE 8.

This ensures you are always training at the optimal stimulus, regardless of life variable.

Calibration Sets

How do you know what RPE 9 feels like ?

Once a month, take an isolation exercise(like chest support row) to true failure.

Verify if your "2 reps left" was actually 2 reps left.

Most people dramatically underestimate their strength.

Tracking it in RepLog

Don't just write "3x10".

Write "225lbs x 10 @ RPE 8".

Next week, if you hit "225lbs x 10 @ RPE 7", you know you got stronger even if the weight didn't change.

Reflecting on your RPE history allows you to see strength gains that aren't visible on the bar yet.

It is the ultimate metric for long - term progress.