RIR Rate & Intensity Calculator
Training Metrics
Understanding Repetitions in Reserve (RIR)
Repetitions in Reserve (RIR) is a method used in resistance training to measure the proximity to muscular failure. Unlike RPE (Rate of Perceived Exertion), which measures how hard a set felt on a scale of 1-10, RIR specifically asks: "How many more reps could I have performed with good technique before failing?"
An RIR of 0 means you reached absolute failure. An RIR of 2 means you stopped the set when you felt you could have performed exactly two more repetitions. This is a critical metric for auto-regulation, allowing lifters to adjust their daily intensity based on their actual performance rather than static percentages.
How This Calculator Works
This calculator uses your weight lifted, reps completed, and your RIR to determine your Estimated One Rep Max (1RM) using the Epley Formula. It then calculates your relative intensity (the percentage of your 1RM you were actually working at).
Example: If you squat 100kg for 8 reps with 2 RIR, your "Total Reps to Failure" is 10. The calculator treats this as a 10-rep max attempt to find your ultimate strength capacity.
RIR Guidelines for Goals
| Goal | Recommended RIR | Description |
|---|---|---|
| Hypertrophy (Muscle) | 1 – 3 RIR | Effective volume without excessive fatigue. |
| Strength (Power) | 2 – 4 RIR | Focus on bar speed and technique. |
| Deload Week | 4+ RIR | Active recovery and fatigue management. |
The Math Behind the RIR Calculator
The calculation follows these logical steps:
- Total Reps: Reps Performed + RIR.
- Estimated 1RM: Weight × (1 + (Total Reps / 30)). This is based on the Epley formula.
- Relative Intensity: Calculated by comparing the weight lifted against the estimated 1RM.