What is a one rep max (1RM)?
A one rep max (1RM) is the maximum weight you can lift for a single repetition of an exercise with good form. It's the gold-standard measure of absolute strength in powerlifting and strength training.
Brzycki Formula 1RM Calculator
The Brzycki formula is considered especially accurate for lower rep ranges (1–10) and is widely used in powerlifting.
w ÷ (1.0278 − 0.0278r) — The Brzycki formula is considered especially accurate for lower rep ranges (1–10) and is widely used in powerlifting.
Use the Brzycki Formula 1RM Calculator
This page is built for Brzycki formula queries where the lifter wants the exact equation, a cleaner lower-rep estimate, and a direct comparison with the rest of the calculator stack.
- Best for: heavier sets in the lower rep ranges when you want a more conservative one rep max estimate
- Rep range: usually strongest from about 1-10 reps, especially on the lower end
- Worked example: 225 lb x 5 reps estimates about 253 lb with the Brzycki equation.
5 reps
One Rep Max
5 reps @ 225lb
253
lb
Brzycki formula
Big Four Strength Standards
Strength levels for a 200lb male, age 30 lifting 253lb in each lift type · enter your details.
Rep Max Projections
Brzycki algorithm
| Reps | Weight (lb) |
|---|---|
| 1RM | 253lb |
| 2RM | 246lb |
| 3RM | 239lb |
| 4RM | 232lb |
| 5RM(current) | 225lb |
| 6RM | 218lb |
| 7RM | 211lb |
| 8RM | 204lb |
| 9RM | 197lb |
| 10RM | 190lb |
| 20RM | 119lb |
Percentage Calculator
Based on 253lb estimated max
| Intensity | Weight (lb) |
|---|---|
| 100% | 253lb |
| 95% | 240lb |
| 90% | 228lb |
| 85% | 215lb |
| 80% | 202lb |
| 75% | 190lb |
| 70% | 177lb |
| 65% | 164lb |
| 60% | 152lb |
| 55% | 139lb |
| 50% | 127lb |
One Rep Max Calculator FAQ
Which 1RM formula is most accurate?
No single formula is universally most accurate — accuracy depends on the individual and rep range. Brzycki is considered most reliable for lower rep ranges (1–6 reps). Epley is widely cited in research. This calculator shows all 7 formulas side by side so you can see the full range of estimates.
How many reps should I use to estimate my 1RM?
Sets of 3–10 reps give the most reliable 1RM estimates. Below 3 reps you're already near your max. Above 10 reps, fatigue factors make estimates less accurate. A set of 5 reps is a common sweet spot.
What is an E1RM (estimated one rep max)?
An E1RM is a calculated estimate of your one rep max based on a submaximal set — for example, the weight you lifted for 5 reps. E1RM formulas let you track strength progress without the risk of actual max testing every session.
Can I use this calculator for squat, bench press, and deadlift?
Yes. This 1RM calculator works for any barbell lift — back squat, bench press, deadlift, strict press, and more. Enter your working weight and rep count and the calculator estimates your max across all 7 formulas.
