FitCalculationOne-rep max: how to use the estimate for your training
Last updated: October 2006
Your one-rep max estimate is a starting point for programming, not a target to test. The 1RM calculator runs five published formulas from a single submaximal set — the weight you lifted and the reps you completed — and shows how they agree and disagree.
Reading the five estimates
The calculator reports Epley, Brzycki, Lombardi, Mayhew, and O'Conner, plus their median. Here is what each tends to do:
| Formula | Tendency | Best for |
|---|---|---|
| Epley | Moderate; slightly generous at low reps | General use; widely cited |
| Brzycki | Moderate; conservative at low reps | Conservative estimates |
| Lombardi | Most generous; diverges at higher reps | Higher rep ranges |
| Mayhew | Moderate; exponential fit to bench data | Bench press |
| O'Conner | Most conservative | Safety-first estimates |
Using the median
Estimates agree more closely at lower reps and diverge as reps increase. The median gives a balanced middle ground: take the median estimate and use it to set your training loads.
Training percentages
Coaches commonly prescribe training as a percentage of your estimated 1RM:
| Intensity | Percentage of 1RM | Purpose |
|---|---|---|
| Accessory/Skill | 50–60% | Form practice, warm-up |
| Hypertrophy | 65–75% | Muscle growth |
| Strength | 75–85% | Strength development |
| Power | 80–90% | Explosive force |
| Peak | 90–95% | Approaching max |
Why you should not test your true 1RM from this
These are estimates, not safe-testing instructions. Attempting an untested heavy single based on them risks injury. True 1RM testing requires progressive warm-up, a spotter, and proper technique in a safe environment. Use the estimate to plan, not to test.
The calculator also flags results above 10 reps as unreliable. Past that point, the relationship between reps and max breaks down, and the formulas extrapolate far beyond their validated range.
Combining with the bulking calculator
The bulking calculator uses your TDEE to set a calorie surplus, and the protein calculator sets your daily protein target. Your 1RM estimate is the bridge between nutrition and training: it tells you what weight to load the bar with for the strength work that makes that surplus count as muscle rather than fat.
Formulas are estimates, not medical advice.
Sources
Sources
- Epley SM. The Poundage Chart: a new approach to the one-repetition maximum. Strength and Conditioning. 1985;7(4):38-39.
Used for: The Epley 1RM estimation formula (weight × (1 + reps/30)).
- Brzycki J. Strength Testing—Predicting a One-Rep Max from Reps-to-Fatigue. Journal of Physical Education, Recreation and Dance. 1993;64(2):124-129.
Used for: The Brzycki 1RM estimation formula.
- Lombardi WL. Single vs. multiple-repetition strength testing to determine 1RM. In: Beginning Weight Training. Human Kinetics; 1989.
Used for: The Lombardi 1RM estimation formula.
- Mayhew JE, Uchima D, Ware JS, et al. Prediction of multiple-repetition bench press maximum in college men. Journal of Strength and Conditioning Research. 1992;6(3):122-127.
Used for: The Mayhew 1RM estimation formula for bench press and similar lifts.
- O'Conner H. Predicting 1RM from submaximal loads. Weight Training Today. 1989;4(8):60-63.
Used for: The O'Conner 1RM estimation formula.