One Rep Max for 420 lbs × 9 reps
One Rep Max Calculator
What is the one rep max for 420 lbs × 9 reps?
Answer
Lifting 420 lbs for 9 reps gives an estimated one rep max of
546 lbs
A set of 9 reps at 420 lbs is
76.9%
of your estimated one rep max
Note: this is an estimate, not a tested max. Rep-based formulas are closest at 2–6 reps and drift further apart as the set gets longer. Warm up and use a spotter before attempting a true single.
How to Calculate One Rep Max
Epley Formula: 1RM = weight × (1 + reps ÷ 30)
The Epley formula assumes that every extra repetition you can complete corresponds to roughly 3.33% more weight on the bar. Put your set into it:
420 × (1 + 9 ÷ 30)
=420 × 1.3
=546 lbs
Training Weights as a % of 1RM
Percentages of your estimated max of 546 lbs, the way most strength programmes prescribe load:
| % of 1RM | Working Weight |
|---|---|
| 95% | 518.7 lbs |
| 90% | 491.4 lbs |
| 85% | 464.1 lbs |
| 80% | 436.8 lbs |
| 75% | 409.5 lbs |
| 70% | 382.2 lbs |
| 65% | 354.9 lbs |
| 60% | 327.6 lbs |
Other One Rep Max Formulas
Published 1RM formulas disagree, and the gap widens with the rep count. This page answers with Epley; here is what the others give for 420 lbs × 9 reps:
| Formula | Estimated 1RM |
|---|---|
| Epley | 546 lbs |
| Brzycki | 540 lbs |
| Lombardi | 523.2 lbs |
| O'Conner | 514.5 lbs |
| Wathan | 553.5 lbs |
| Lander | 543.6 lbs |
| Mayhew | 540.3 lbs |
Found an error in the calculation or the information?
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See Also
- BMI Meaning - Check what given BMI means
- BMI Calculator (Imperial) - Body Mass Index Calculator (ft/in/lbs)
- BMI Calculator (Metric) - Body Mass Index Calculator (kg/cm)
- Ideal Weight Calculator (Imperial) - Find out the Ideal Weight for a given Height in feet/inches
- Ideal Weight Calculator (Metric) - Find out the Ideal Weight for a given Height in centimeters
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One Rep Max Table for 420 lbs
One Rep Max Calculator
This calculator estimates your one-rep max (1RM) — the heaviest weight you could lift for a single repetition — from a set you have already completed. For example, it can help you find out what is the one rep max for 420 lbs × 9 reps? (The answer is: 546 lbs). Enter the weight you lifted (e.g. 420), pick pounds or kilograms, and enter how many reps you managed (e.g. 9).