One Rep Max (1RM) Calculator
Estimate your max lift from a working set you actually did — without testing to failure.
Training Percentages
| % of 1RM | Weight | Typical Reps |
|---|
What Is a 1RM?
One Rep Max (1RM) is the maximum weight you can lift once with proper form. It's the standard reference point for strength: programming periodization uses percentages of 1RM, and strength comparisons across athletes are 1RM-based. Powerlifting competitions are decided by best successful 1RMs in squat, bench press, and deadlift.
Why Estimate Instead of Test?
True 1RM attempts are demanding, increase injury risk, require a spotter, and need full recovery before the next session. Estimating from a normal working set (2-6 reps) is:
- Safer — no maximal force on joints and connective tissue
- Repeatable — can be done every training session
- Accurate enough — within ±5% for programming purposes
The three formulas here (Epley 1985, Brzycki 1993, Lombardi 1989) are the most widely-used in sports science. Averaging them smooths individual biases.
What "strong" looks like for a 180 lb (82 kg) man
Strength standards per Strength Level data and ExRx, expressed as 1RM:
| Level | Squat | Bench Press | Deadlift |
|---|---|---|---|
| Beginner | ~135 lb (61 kg) | ~135 lb (61 kg) | ~165 lb (75 kg) |
| Novice | ~225 lb (102 kg) | ~175 lb (79 kg) | ~275 lb (125 kg) |
| Intermediate | ~315 lb (143 kg) | ~225 lb (102 kg) | ~385 lb (175 kg) |
| Advanced | ~425 lb (193 kg) | ~315 lb (143 kg) | ~500 lb (227 kg) |
| Elite | ~550 lb (249 kg) | ~410 lb (186 kg) | ~620 lb (281 kg) |
Numbers scale with bodyweight. The classic "1/2/3/4 plate" goal (135/225/315/405 lb) maps roughly to novice/intermediate/advanced for an average man on bench/squat/deadlift respectively. Female standards run roughly 60-65% of male at the same training level.
How to Use the Percentages
| % of 1RM | Rep Range | Training Goal |
|---|---|---|
| 90-100% | 1-3 | Maximal strength |
| 80-90% | 3-6 | Strength |
| 70-80% | 8-12 | Hypertrophy (muscle growth) |
| 60-70% | 12-15 | Muscular endurance |
| 40-60% | 3-8 explosive | Power / speed-strength |
| 30-50% | 15-30 | Endurance, conditioning |
Frequently Asked Questions
How accurate is this estimate?
Most accurate for 2-6 rep sets. Beyond 8-10 reps, estimates drift because muscular endurance increasingly matters more than pure strength. For best accuracy, use the heaviest set you've done in the past few weeks.
Which formula is best?
Brzycki tends to be conservative, Lombardi aggressive, Epley moderate. The average smooths out their biases. For elite-level work where the difference matters, the NSCA recommends actually testing 1RM under supervised conditions.
Should beginners test their 1RM?
Not for the first 6 months. Form is more important than peak load, and beginners' 1RM changes weekly anyway. Use prescribed-rep programs (e.g., 5×5, Starting Strength) until form is solid and progress slows.
What's the most dangerous 1RM lift?
1RM bench press without a spotter — the bar can pin you to the bench. Always use a power rack with safety arms, a spotter, or never attempt true 1RM bench alone. Squat and deadlift you can bail out of; bench press you can't.