What this tool does
The calculator combines Epley and Brzycki formulas, shows an estimated 1RM, gives a low-to-high formula range, and builds a percentage table you can use for training loads. US pounds are shown first, with Metric available from the unit selector.
How to use it
- Choose US or Metric units and enter the weight you lifted.
- Enter how many good reps you completed with that weight.
- Use the result as an estimate, not a guaranteed max.
- Do not use this tool to justify max attempts through pain or unsafe technique.
Important limitations
These numbers are planning estimates, not a diagnosis or individualized medical advice. They can be less appropriate during pregnancy, breastfeeding, adolescence, illness, recovery from an eating disorder, or when a clinician has given you specific nutrition instructions.
Frequently asked questions
Why is there a range?
Different 1RM formulas produce slightly different estimates. Showing a range is more honest than pretending one number is exact.
Is this accurate for high reps?
The estimate is usually more useful at lower reps. Accuracy tends to drift as reps get higher, which is why the tool limits input to 1–12 reps.
What is the percentage table for?
It gives rough loading targets such as 80%, 85% or 90% of estimated 1RM for programming sets.