One Rep Max Calculator – 1RM for Bench Press, Squat & Deadlift (kg)
Use this free one rep max calculator to estimate your bench press, squat or deadlift 1RM in kilograms from a lighter set. It uses six proven formulas, shows the average, and gives you a table of training weights by percentage so you can plan your next block.
One rep max calculator
Enter the weight and reps from a hard set, then press calculate.
What is a one rep max?
Your one rep max (1RM) is the heaviest weight you can lift for a single rep with good form. Testing it directly is tiring and carries injury risk, so this one rep max calculator estimates it from a lighter set. Enter the weight in kilograms and the reps you completed, and it predicts your max for the bench press, squat, deadlift or any other lift, plus the weights to train at for different rep ranges.
How to use the 1RM calculator
- Warm up, then do one hard set where you stop one or two reps before failure, or at failure if you have a spotter.
- Enter the weight and the number of reps you completed.
- Read your estimated 1RM and the training weights table.
Estimates are most accurate for sets of 2 to 10 reps. Beyond about 12 reps, fatigue and conditioning matter more than strength, so predictions become less reliable.
Bench press, squat and deadlift 1RM formulas
The calculator uses six well-known formulas and shows each one, along with the average. The Epley formula is weight × (1 + reps ÷ 30), and the Brzycki formula is weight × 36 ÷ (37 − reps). Worked example: 80 kg for 6 reps gives Epley 80 × 1.2 = 96 kg and Brzycki 80 × 36 ÷ 31 = 92.9 kg. The others (Lombardi, Mayhew, O'Conner and Wathan) land in a similar range. Squat and deadlift predictions can be a little less precise than bench press, since those lifts are more technique and fatigue dependent.
Training percentages
| % of 1RM | Approx. reps | Typical goal |
|---|---|---|
| 90 to 100% | 1 to 4 | Maximal strength |
| 80 to 90% | 4 to 8 | Strength and size |
| 65 to 80% | 8 to 15 | Muscle growth |
| 50 to 65% | 15 or more | Endurance and warm-ups |
Fuel your strength training
Strength comes from training, sleep and food. Aim for enough daily protein, which you can set with the protein intake calculator, and eat enough overall using the calorie calculator. Browse protein powder, pre workout and creatine, and try the creatine calculator for dosing.
Frequently asked questions
How do I calculate my one rep max for bench press?
Lift a weight for several reps close to failure, then enter the weight and reps. The calculator predicts the heaviest single you could lift.
Which 1RM formula is the most accurate?
No single formula wins for everyone. Epley and Brzycki are the most used, and the average of several is a sensible estimate, especially for sets under 10 reps.
Is it safe to test my true 1RM?
It carries more injury risk than training sets, so use a spotter and proper warm-up, or simply use an estimate like this one.
How often should I recalculate my 1RM?
Every 4 to 8 weeks, or when your training sets get heavier. Your training weights should follow your current max, not an old one.
Does this work for deadlift and squat?
Yes, though predictions may be slightly less precise for squat and deadlift. Use sets of 5 reps or fewer for the best estimate.
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General information only. A 1RM is an estimate. Use a spotter, warm up properly and lift within your ability. If you have an injury or health condition, check with your doctor or a qualified trainer first.