Bench Press 1RM Calculator
Inputs
Results
Prediction only — best used for hard sets around 1–10 reps.
Action
Use this Bench Press 1RM Calculator to estimate your one-repetition maximum (1RM) from a weight you lifted for multiple repetitions. The calculator compares four common prediction formulas and provides an average estimate.
Important: A calculated 1RM is a prediction, not a guaranteed maximum. Do not attempt a heavy single based only on the calculator result.
Bench Press 1RM Formulas
The calculator uses the weight lifted and number of repetitions completed.
Epley:
1RM = weight × (1 + reps ÷ 30)
Brzycki:
1RM = weight × 36 ÷ (37 − reps)
Lombardi:
1RM = weight × reps0.10
O’Conner:
1RM = weight × (1 + 0.025 × reps)
The calculator also shows:
Average estimate = sum of the four estimates ÷ 4
Different formulas can produce different results because they model the relationship between repetitions and maximal strength differently.
Worked Example
Suppose you bench press 100 kg for 5 controlled repetitions.
Epley:
100 × (1 + 5 ÷ 30) ≈ 116.7 kg
Brzycki:
100 × 36 ÷ (37 − 5) = 112.5 kg
Lombardi:
100 × 50.10 ≈ 117.5 kg
O’Conner:
100 × (1 + 0.025 × 5) = 112.5 kg
Average estimate:
(116.7 + 112.5 + 117.5 + 112.5) ÷ 4 ≈ 114.8 kg
This set therefore suggests a bench-press 1RM of roughly 115 kg, with individual formulas producing estimates of about 113–118 kg.
How to Get a Better Estimate
- Use a hard set performed with consistent technique and full range of motion.
- Prediction equations are generally more useful with lower-to-moderate repetition sets, particularly around 10 reps or fewer.
- Use the same bench-press style when tracking progress, such as paused or touch-and-go repetitions.
- A set stopped well before your repetition limit may underestimate your likely 1RM.
- Do not deliberately perform unsafe repetitions to failure simply to improve the calculator estimate.
Important Notes
- A predicted 1RM can differ from a directly measured 1RM.
- Prediction accuracy varies with repetition count, training experience, individual strength endurance, exercise technique, and the equation used.
- Higher-repetition sets generally produce greater uncertainty when predicting maximum strength.
- Fatigue, sleep, illness, previous training, nutrition, and readiness can affect performance on a particular day.
- Paused, touch-and-go, close-grip, competition-style, and partial-range bench presses should not be treated as identical lifts when comparing results.
- The average of several equations can be useful as a practical training estimate, but it is not automatically more accurate for every lifter.
- If attempting heavy bench-press loads, use appropriate safety equipment or a competent spotter and progress gradually.
- People with an injury, recent surgery, cardiovascular concerns, or other conditions affecting resistance exercise should seek appropriate professional guidance before maximal-strength testing.