Free tool
1RM Calculator
Estimate your one-rep max from any hard set — and if you left reps in the tank, say so: RIR-adjusted estimates are how the app thinks.
Estimated 1RM (Epley)
116.7 kg
Brzycki cross-check: 112.5 kg
95%
110.8 kg
90%
105.0 kg
85%
99.2 kg
80%
93.3 kg
75%
87.5 kg
70%
81.7 kg
65%
75.8 kg
60%
70.0 kg
This is an estimate, not a measured max. Lower-rep inputs require less extrapolation; use the result as a planning aid.
How it works
We calculate Epley (load × (1 + reps/30)) and show Brzycki as a cross-check. When the formulas diverge, the interface presents the result as an estimate rather than pretending it is a measured max.
Why RIR matters
SwoleCraft adds reported reps in reserve to completed reps before applying its Epley estimate. That is a transparent product heuristic, not a claim that two sets are physiologically identical.
What SwoleCraft does with this number
Your e1RM is recomputed from every logged set and tracked as a trend line, not a trophy. The progression engine uses the trend to detect plateaus early and schedule interventions — long before you'd notice them yourself.
In the app
This math runs automatically on every set you log — no typing numbers into a website between sets.
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