FREE TOOL
1RM Calculator
Estimate your one-rep max from any set of 2 to 10 reps, with Epley and Brzycki side by side.
Enter a weight and the reps you completed with it to estimate your one-rep max.
Estimates only. Nothing here is medical advice, and nothing you enter leaves your browser.
How this calculator works
The full explanation of the formula, its limits, and how to adjust the result against real-world data is in the Learn article this tool is built on.
Frequently asked questions
How accurate is a 1RM calculator?
Within a few percent for sets of 2 to 5 reps taken close to failure on well-practiced barbell lifts. Accuracy drops as reps climb past 8 to 10 and on exercises where fatigue, not strength, ends the set.
Epley or Brzycki: which formula should I use?
They give nearly identical answers below about 6 reps. Brzycki tends to be slightly conservative at higher reps and Epley slightly generous. Either is fine as long as you use the same one consistently to track progress.
Should I test my true 1RM?
Most lifters never need to. An estimated max from a heavy triple carries far less injury risk and fatigue cost, and is accurate enough to set training percentages. Test a true max only when it matters, such as for a powerlifting meet.
How do I use my 1RM for programming?
Percentages of e1RM define the working weights in most strength programs: roughly 70 to 80 percent for sets of 5 to 8, 80 to 90 percent for sets of 2 to 4. Recalculate every few weeks as your top sets improve.
Related reading
RPE Training: How to Autoregulate Your Workouts
RPE lets you adjust training intensity based on how you actually feel, not just what the spreadsheet says. Here's how to use it properly.
Strength vs. Hypertrophy: Programming for the Outcome You Want
Strength and hypertrophy are related but distinct adaptations that respond to different training variables. Learn how rep ranges, intensity, and volume interact, and how to periodize between strength and hypertrophy phases for maximum results.
Personal Records: What Actually Counts as a PR
Not every heavy day is a personal record, and not every PR is a heavier bar. Here's how to define a true PR so the badge actually means something.