A worked example
Lifting 185 lb for 5 reps projects to an estimated one-rep max of about 212 lb — Epley gives roughly 216 lb, Brzycki gives about 208 lb.
Frequently asked questions
Why two different formulas?
Epley and Brzycki were each fitted to different datasets and behave slightly differently across rep ranges — averaging them gives a reasonable middle estimate rather than betting on just one model.
What's the percentage table actually for?
Programming training percentages — many strength programs prescribe weight as a % of your 1RM (e.g., 'work up to 80% for 3 sets of 5') rather than an absolute number, so having the breakdown handy saves recalculating it each time your max changes.
Should I actually attempt a true 1-rep max to test this?
Not necessary, and often not advisable without supervision — these formulas exist specifically so you don't have to risk a true maximal single just to know roughly where you stand.
This calculator provides estimates for general informational purposes only. Always use proper form and appropriate spotting/safety equipment when training near your limits.