Use the 1RM calculator
How this 1RM calculator works
Enter a recent working set (weight and reps) to estimate your one-rep max (1RM). The calculator uses the Epley formula, then produces training percentages you can actually load on a bar, plus a plate breakdown based on your bar weight.
Calculation method
Estimated 1RM = weight × (1 + reps ÷ 30). Percentage-based working weights are then computed at 60%, 70%, 75%, 80%, 85%, 90%, and 95% of the estimated 1RM. Bar loading suggests pairs of plates that most closely match each target weight above your chosen bar.
Real-life uses
- Programming percentage-based strength sessions
- Deciding what weight to attempt for an AMRAP or back-off set
- Pacing a peaking block leading up to a max attempt
- Quickly converting between kg and lb training weights
Frequently asked questions
Which formula is used?
Epley, which is reliable at 1–10 reps. Above 10 reps, estimates become less accurate.
Is 1RM safe to test?
Not always. Most lifters benefit more from training at 70–90% with a calculated 1RM than from actually maxing out.
How often should I re-test?
Every 6–12 weeks is plenty for most lifters, or after any significant programme change.