Free strength tool
Pick your reps and how hard the set felt on the RPE scale. We convert it to reps in reserve and to a percentage of your one-rep max, and lay out the full RPE chart so you can read any rep and effort at a glance. Add the weight you lifted to estimate your 1RM too.
How it works
RPE (rating of perceived exertion) scores how hard a set was from 6 to 10. RPE 10 means nothing left, RPE 8 means about two more reps were possible. RIR (reps in reserve) is the same idea stated directly: RIR = 10 minus RPE, so RPE 8 is 2 RIR. Ironstead lets you log either.
A given number of reps taken at a given effort corresponds to a fairly stable share of your one-rep max. Five reps at RPE 8 sits near 81 percent for most lifters. That relationship is what the chart captures, so you can turn a target effort into a target load without maxing out.
Rows are reps, columns are RPE with the matching RIR underneath. Every cell is a percentage of your 1RM. The same percentage repeats down a diagonal, because a hard set of few reps and an easier set of more reps can demand the same relative load.
Autoregulate: instead of a fixed weight, chase a rep and RPE target and let the load follow how you feel that day. Ironstead records RPE or RIR on every set, keeps your estimated 1RM current from that data, and shows the trend over time.
Common questions
Ironstead records RPE or RIR on every set and keeps your estimated 1RM current automatically, so your percentages always reflect real training. Free for athletes.
Estimates are guidance, not medical advice. Warm up properly and use a spotter for heavy attempts.
