One rep max calculator.
Enter the weight and the reps you completed in a hard set, and get your estimated one-rep max (e1RM) with a percentage table for planning your working sets. It uses the same formula as the Club 1000 Plus training log, so the number matches what the app shows.
Training weights from your max
Loads rounded to the nearest 5 lb (2.5 kg) plate step.
| Share of 1RM | Load |
|---|---|
| 100% | 265 lb |
| 95% | 250 lb |
| 90% | 240 lb |
| 85% | 225 lb |
| 80% | 210 lb |
| 75% | 200 lb |
| 70% | 185 lb |
| 65% | 170 lb |
| 60% | 160 lb |
| 55% | 145 lb |
| 50% | 130 lb |
How the estimate is worked out
A set taken close to failure says a lot about the heaviest single you could manage. The calculator takes the weight and reps and averages three formulas that were fitted to real lifters across a wide range of reps:
- Mayhew: 100 × weight ÷ (52.2 + 41.9 × e−0.055 × reps)
- Wathan: 100 × weight ÷ (48.8 + 53.8 × e−0.075 × reps)
- Lombardi: weight × reps0.10
A single rep is its own max. The result is rounded to one decimal place. For example, 225 lb for 5 reps estimates 264.8 lb, and 135 lb for 12 estimates 182.3 lb.
In the Club 1000 Plus workout log the same estimate updates on every set you save, and your best e1RM per lift is charted over time on the desktop dashboards, so you can see strength move week to week without testing a max.
Estimates are informational fitness figures, not medical advice. Lift within your ability and use a spotter or safety bars for heavy sets.
One rep max questions.
What is a one-rep max?
Your one-rep max (1RM) is the heaviest weight you can lift for a single complete repetition with good form. Most training programmes set working weights as a percentage of it, which is why the table above lists 50% to 100%.
How accurate is an estimated 1RM?
It is an estimate, and it is closest when the set was hard, done with good form and between about 2 and 10 reps. A set of 20 tells you more about endurance than about a single heavy rep, so the estimate drifts further from what you would actually lift. Treat it as a guide for planning, not a tested max.
Which formula does this calculator use?
The average of three published formulas: Mayhew, Wathan and Lombardi. Epley and Brzycki, the two best-known, are reasonable for low reps but break down past about 15. Averaging three formulas that hold up from 1 to 100 reps keeps the estimate steadier. It is the same calculation the Club 1000 Plus training log uses for every set you log.
Should a missed rep count?
No. Count only the reps you completed. In the app, a set marked to failure scores the reps before the failed one, so a missed fifth rep estimates from four.
Do I need to test my one-rep max?
No. Many lifters never test a true single and track their estimated max instead, because it moves with ordinary training. If you do test one, use a spotter or safety bars, warm up properly, and stop if form breaks down.
Can an estimated max put me on the 1000 pound club board?
No. The 1000+ board lists only real one-rep maxes, reviewed on video against published standards. Use the 1000 lb club calculator to see how close your estimated total is.
Let the log do the maths.
Every set you save updates your estimated max, lift by lift.