RIR calculator FAQ

What does RIR mean?

RIR stands for reps in reserve: how many more reps you could have done before failure. 2 RIR means you stopped with about two good reps left.

How does this RIR calculator work?

Enter the weight you lifted, the reps you did and your RIR. It estimates your one-rep max, then suggests a weight for the reps you want to do on your next set.

How many reps in reserve should I leave?

For most people building muscle, 0–3 RIR on working sets is a good range. Beginners should stay closer to 2–3 while they learn the movement.

What's the minimum weight increment for?

It rounds the suggested load to weights you actually have, such as 2.5 lb or 5 lb plates.

Is the one-rep max estimate accurate?

It's an estimate. It's most reliable with sets of about 3–10 reps and an honest RIR, and there's no need to test a true max to use it.