Testing a true one-rep max is tiring and risky. A set of a few reps predicts it well, most accurately from sets of 10 or fewer reps taken close to failure.
How to use the One Rep Max Calculator
- Exercise
- Formula
- Weight lifted
- Reps
Results update as you type, every field has its own unit menu, and everything is calculated in your browser.
How it works
Choose the lift and formula, enter the weight and the reps.
Tips
- Estimate 1RM from sets of 10 reps or fewer for best accuracy.
- Use a training max of about 90% of your 1RM for programmes.
- Always use a spotter or safety bars when testing heavy lifts.
- Everything is calculated in your browser.
Common mistakes to avoid
- Testing true maxes too often.
- Using sets to failure with poor form to estimate 1RM.
- Adding weight too quickly week to week.
Inputs explained
| Field | What to enter |
|---|---|
| Exercise | Choose one: Bench press, Squat, Deadlift, Overhead press … |
| Formula | Choose one: Epley, Brzycki, Lombardi, NSCA percentage table |
| Weight lifted | Units: kg, lb |
| Reps | A number |
What each result means
- Epley = [Weight lifted]×(1 + [Reps]÷30)
- Brzycki = [Weight lifted]×36÷(37 – min([Reps], 36))
- Lombardi = [Weight lifted]×[Reps]^0.1
- 95% of 1RM (≈ 2 reps) = [Estimated one-rep max]×0.95
- 90% of 1RM (≈ 4 reps) = [Estimated one-rep max]×0.9
- 85% of 1RM (≈ 6 reps) = [Estimated one-rep max]×0.85
- 80% of 1RM (≈ 8 reps) = [Estimated one-rep max]×0.8
- 75% of 1RM (≈ 10 reps) = [Estimated one-rep max]×0.75
- 70% of 1RM (≈ 12 reps) = [Estimated one-rep max]×0.7
- 60% of 1RM (≈ 15–20 reps) = [Estimated one-rep max]×0.6
- 50% of 1RM (≈ 20+ reps) = [Estimated one-rep max]×0.5
Example values
How the main result changes when Weight lifted changes and everything else stays at the example values above:
| Weight lifted (kg) | Estimated one-rep max (kg) |
|---|---|
| 50 | 57.5 |
| 75 | 86.2 |
| 100 | 114.9 |
| 125 | 143.7 |
| 150 | 172.4 |
| 200 | 229.9 |
Formula
Epley: 1RM = w(1 + r/30) · Brzycki: w × 36/(37 − r) · Lombardi: w × r^0.10 · NSCA table: 1RM = w ÷ %(reps) (2 reps 95%, 3 93%, 4 90%, 5 87%, 6 85%, 7 83%, 8 80%, 9 77%, 10 75%)
Worked example
Inputs: Exercise: Bench press; Formula: NSCA percentage table; Weight lifted: 100 kg; Reps: 5.
Results: Estimated one-rep max = 114.9 kg; Epley = 116.7 kg; Brzycki = 112.5 kg; Lombardi = 117.5 kg; 95% of 1RM (≈ 2 reps) = 109.2 kg; 90% of 1RM (≈ 4 reps) = 103.4 kg; 85% of 1RM (≈ 6 reps) = 97.7 kg; 80% of 1RM (≈ 8 reps) = 92 kg; 75% of 1RM (≈ 10 reps) = 86.2 kg; 70% of 1RM (≈ 12 reps) = 80.5 kg; 60% of 1RM (≈ 15–20 reps) = 69 kg; 50% of 1RM (≈ 20+ reps) = 57.5 kg.
Key terms
- 1RM
- Heaviest weight you can lift once with good form.
Frequently asked questions
Which formula is best?
All are similar for 3–8 reps; the NSCA table is a reliable standard.
Can I use a set of 15 reps?
Accuracy falls above 10 reps.
Does it differ between lifts?
Slightly, as lower-body lifts allow more reps at the same %.
Should beginners test a 1RM?
No, estimate it from a 5–8 rep set.