What this calculator does

A one rep max estimate helps set training loads without testing a true maximum. It is most useful for low to moderate rep sets with good technique.

Formula used

The headline estimate uses the Epley formula: weight multiplied by one plus reps divided by 30. The calculator also shows common training percentages.

How to read the result

The estimate becomes less reliable at high rep counts. Fatigue, exercise type, technique and training history all affect the result.

Assumptions

  • Best suited to compound lifts.
  • Assumes the set was close to maximum effort.
  • Not a substitute for safe coaching or spotting.

Sources and checks

This calculator uses a standard public formula. Where rules or thresholds can change, source links are listed on the relevant page.

Frequently asked questions

Should I test a real one rep max?

Only if it fits your training and you can do it safely. Many lifters use estimates for programming instead.