1rm formula
The 5 Best Formulas to Estimate 1RM
Compare common 1RM formulas, understand what each one does well, and pick the right one for your training.
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1RM Calculator
Estimate your one-rep max with Epley, Brzycki, and Lander formulas.
Open calculator pageWhy formulas disagree
A formula is only a model of fatigue. Different models assume a different cost per rep, which is why the same 100 kg x 8 set does not always produce the same max estimate.
The right formula is usually the one that best matches how you personally perform on low-rep sets.
The formulas most lifters should care about
Epley, Brzycki, and Lander cover most practical needs. O'Conner and Lombardi are sometimes discussed, but the first three already give enough spread to understand likely max range.
- Epley favors straightforward linear scaling.
- Brzycki pulls estimates down slightly when reps climb.
- Lander smooths between aggressive and conservative estimates.
- Lombardi tends to reward high-rep endurance more heavily.
- O'Conner is simple but less common in modern tools.
| Formula | Style | Best use case |
|---|---|---|
| Epley | Balanced linear estimate | General 3-8 rep barbell work. |
| Brzycki | More conservative curve | Lifters who overshoot from high reps. |
| Lander | Middle-ground polynomial | Programming a realistic max range. |
| Lombardi | Power-based scaling | Exploring upper-end estimates from rep work. |
| O'Conner | Simple heuristic | Quick rough checks when precision is not the priority. |
Formula choice depends on the lift
Bench press often estimates cleanly from moderate rep work. Squat and deadlift estimates get messier because technique and fatigue change more dramatically across rep ranges.
That is why coaches prefer to compare all three formulas rather than trust a single number blindly.
Use formulas as a range, not a verdict
The smart move is to use the formulas to create a reasonable operating range, then choose a training max that lets the program succeed. A slightly conservative estimate is better than a perfectly impressive spreadsheet.