Estimating maximum strength without testing it directly
Your one-rep max (1RM) — the most weight you could lift for a single rep — is a useful benchmark for programming strength training, but actually testing it requires a maximal, fatiguing attempt that carries real injury risk and isn't necessary for most training goals. The Epley formula, used here, estimates 1RM from a much safer working set.
1RM = weight × (1 + reps ÷ 30)
The formula is most reliable for sets of roughly 1 to 10 reps performed close to muscular failure — the further beyond 10 reps you go, the less accurate the estimate becomes, since high-rep sets start to test muscular endurance more than maximal strength.
Using the percentage table for programming
Most structured strength programs prescribe training weights as a percentage of 1RM rather than an absolute number, because it scales automatically as your strength changes. Higher percentages (85-95% of 1RM) target maximal strength and power with low reps; moderate percentages (65-80%) are common for hypertrophy-focused training with moderate rep ranges.
Recalculate as you progress
Your estimated 1RM will drift as you get stronger, so it's worth recalculating periodically — ideally from a recent honest working set close to failure — rather than anchoring training percentages to a number calculated months earlier.