The one-rep max calculator estimates a 1RM from weight × reps using Epley or Brzycki—useful for percent-based sets.
How to use
- Log a fresh set’s weight and reps.
- Pick a formula (Epley for moderate reps; Brzycki for low reps).
- Read estimated 1RM and sample training percents—don’t load the bar to the estimate blindly.
Example
100 kg × 5, Epley → ~117 kg estimated 1RM; 85% ≈ 99 kg for 5-rep work (rounded).
Training math—not competition testing; use spotters on heavy lifts.
Frequently asked questions
What is one-rep max (1RM)?
The heaviest weight you could lift once with good form. This page estimates it from a submax set (weight × reps)—no true max attempt required.
Which 1RM formula?
This page offers Epley, Brzycki, Lombardi, Mayhew, O’Conner, and Wathan—each card notes typical rep ranges. Switch to compare, then use the % weight table and goal zones in results.
Load the bar to the estimate?
Not recommended for a max attempt. Formulas err and fatigue matters. Use the estimate for percent-based training (e.g. 85% × 5) with spotters.
What if reps = 1?
At 1 rep, the estimate equals your entered weight. Log a fresh set—not a fatigued final set—for a useful number.
Link to cardio tools?
Lifting burns energy too—rough duration estimates on the calories burned calculator (strength preset). For running pace, see the pace calculator.
Same formula for every lift?
Formulas assume big compound lifts. Isolation or highly technical lifts have more error—use as a rough load guide only.
Can I save weight and reps?
Yes. Copy link below the form keeps your current inputs so you can share the scenario or save it for later.