What is One-Rep Max Calculator?
This one-rep max calculator runs locally in your browser. Enter your training weight (1-1000, switchable between kg and lb) and the reps you completed (1-36 via slider), then pick a formula: Epley (1RM = W × (1 + R/30)) or Brzycki (1RM = W × 36/(37-R)). The estimated 1RM updates instantly to one decimal place, with a 90% target-weight hint. A 10-row training load table is generated alongside: 100% (1RM), 95% (2RM), 90% (3RM), 85% (5RM), 80% (8RM), 75% (10RM), 70% (12RM), 65% (15RM), 60% (20RM), and 50% (conditioning/rehab). All math happens in your browser — nothing is uploaded. The 1RM is an estimate; actual strength depends on training state and movement pattern, so use a spotter or safety pins for heavy lifts.
▶Use Cases5 scenarios
- ◆Planning bench, squat, and deadlift programs
- ◆Estimating max strength from current performance
- ◆Calculating target weights for each intensity zone
- ◆Setting up periodized training intensities
- ◆Logging progress over time
▶How to Use5 steps
- 1Enter the training weight (1-1000) and pick kg or lb
- 2Set reps with the slider (1-36)
- 3Choose the Epley or Brzycki formula
- 4Read the estimated 1RM and 90% target weight
- 5Review the 10-row training load table
▶Features8 features
- ✓Free
- ✓No signup
- ✓Epley and Brzycki formulas
- ✓kg/lb unit switch
- ✓Reps 1-36
- ✓One-decimal results
- ✓10-row load table
- ✓100% local calculation
▶FAQ7 questions
What is a one-rep max calculator?
An online strength-estimation tool. Input: training weight (1-1000, kg or lb) and reps completed (1-36). Output: an estimated 1RM using the Epley or Brzycki formula, plus a 10-row training load table. Used for planning bench, squat, and deadlift training. All calculation happens locally in your browser — no uploads.
Which formulas are supported?
Two: Epley (1RM = W × (1 + R/30)) and Brzycki (1RM = W × 36/(37-R)). Switch between them to compare estimates.
What is the rep range?
1 to 36 reps via the slider. The Brzycki formula becomes more conservative as reps approach 36.
Can I switch weight units?
Yes. kg and lb are both supported; the 1RM and load table convert automatically.
What rows are in the load table?
10 rows: 100% (1RM), 95% (2RM), 90% (3RM), 85% (5RM), 80% (8RM), 75% (10RM), 70% (12RM), 65% (15RM), 60% (20RM), and 50% (conditioning/rehab).
How accurate is the result?
The 1RM is a formula-based estimate. Actual max strength depends on training state and movement pattern — adjust your working weights with real-world testing.
Is my data uploaded?
No. All calculation happens locally in your browser with no network requests.