Reps in reserve, or RIR, estimates how many more reps you could have completed while keeping your intended technique. If you think two more were possible, record 2 RIR.
It’s an estimate, and accuracy takes practice. Use it alongside reps, load, and technique notes to understand how demanding your sets were.
Reaching failure on every set is not a universal requirement for progress. Choose an effort target that makes sense for your experience, exercise, and program.
Next session: add an honest RIR estimate to your working-set entries.
Further reading: Grgic and colleagues’ review of failure and non-failure training .