Your estimated one rep max is the most useful number in strength training. It tells you what weight to put on the bar for every set, in every session, across a 12-week program. Without it, you're guessing. And guessing means you're either training too light to make progress or too heavy to recover.
Most people hear "one rep max" and picture someone maxing out on the bench press with two spotters. That's not what I'm describing. At CoachCMFit, we calculate estimated 1RM (e1RM) using AMRAP sets and a formula. No true max effort. No elevated injury risk. Just math.
The Epley Formula: How It Works
The Epley formula was developed by Boyd Epley at the University of Nebraska in 1985 and remains the most widely used 1RM prediction equation in strength and conditioning. Greg Nuckols at Stronger by Science has validated it extensively in practice.
Most accurate with 3–8 rep sets. Accuracy decreases above 10 reps.
Example: You squat 185 lbs for 8 reps before form starts to break. Your e1RM equals 185 x (1 + 8/30), which works out to 185 x 1.267, giving you an estimated max of roughly 234 lbs. You train Block 2 at 65-75% of that number, which puts your working sets between 152 and 175 lbs. Now you have a real target instead of grabbing whatever feels okay.
The AMRAP Method: How to Test Without Maxing Out
AMRAP stands for As Many Reps As Possible. You load a weight you can lift for roughly 5-8 reps, do as many reps as you can with perfect form, stop one rep before form breaks, and plug the result into the Epley formula.
When and How to Test
CoachCMFit uses an AMRAP set in the final training week of each 12-week block on every anchor compound. The last set of the squat, deadlift, bench press, and overhead press becomes an AMRAP. The data feeds the Epley formula, which recalculates e1RM for the next block. This is how exact weights get prescribed for Block 2 and Block 3, not percentages the client has to calculate.
The key is stopping one rep before form breaks. This isn't a comfort thing. It's accuracy. If you grind out two ugly reps at the end, the formula overpredicts your max and you'll train too heavy in the next block. Stop clean. The number is more useful that way.
1RM Percentage Chart for Training
| % of 1RM | Rep Range | Goal |
|---|---|---|
| 50-60% | 15-20+ | Warm-up, technique, rehab |
| 60-70% | 12-15 | Foundation / high-rep hypertrophy |
| 65-75% | 8-12 | Build block / primary hypertrophy |
| 75-85% | 6-10 | Challenge block / strength-hypertrophy |
| 85-90% | 3-5 | Strength / heavy work |
| 90-100% | 1-3 | Max strength, peaking phases |
CoachCMFit's 12-Week Periodization System moves clients through three blocks: Foundation (12-15 reps, roughly 60-70% e1RM), Build (8-12 reps, 65-75%), and Challenge (6-10 reps, 75-85%). The e1RM calculated at the end of the first cycle sets the load targets for the second cycle, and so on. Each 12-week cycle gets heavier because your e1RM increases as you get stronger.
1RM Examples by Exercise
Here's how to apply the method practically. These are real examples from CoachCMFit client programming.
| Exercise | AMRAP Result | Estimated 1RM | Block 2 Target (70%) |
|---|---|---|---|
| Back Squat | 135 lbs x 8 | 171 lbs | 120 lbs |
| Bench Press | 95 lbs x 6 | 114 lbs | 80 lbs |
| Romanian Deadlift | 155 lbs x 7 | 191 lbs | 134 lbs |
| Overhead Press | 65 lbs x 5 | 76 lbs | 53 lbs |
The coach does this math, not the client. The client sees "Squat: 120 lbs, 3x10" on their program. No percentages, no formulas at the gym. That clarity is what makes the tracking system work.
Nuckols and Israetel both validate the Epley formula for practical programming use. A 2017 review in the Journal of Strength and Conditioning Research found prediction error of 3-7% when AMRAP sets stay in the 3-8 rep range. Above 10 reps, muscular endurance contaminates the result and error climbs to 10-15%. Stick to the 3-8 rep zone for clean estimates.
When to Recalculate
Every 12 weeks, at the end of a training block. Not more often. Recalculating too frequently creates noise in the data and tempts you to chase numbers instead of training. The e1RM is a tool for programming, not a performance metric to obsess over.
If you're following CoachCMFit's periodization system, the terminal AMRAP in week 12 handles this automatically. Your progressive overload over 12 weeks drives the number up. You come back to the same AMRAP protocol a stronger person.
Quick recalculation shortcut: If you hit a surprise PR in the middle of a block, say you squat 5 lbs heavier than programmed for all your sets, you don't need to recalculate your full 1RM. Just note it. The terminal AMRAP at the end of the cycle will capture it properly. Mid-cycle re-testing creates more confusion than clarity.
- Choose your main compound: squat, deadlift, bench press, or overhead press
- Warm up fully: 2 sets at 50%, 1 set at 70% of your estimated working weight
- Load a weight you can lift for 5-8 reps
- Do as many reps as possible, stopping 1 rep before form breaks
- Plug into Epley: weight × (1 + reps ÷ 30)
- Train Block 2 at 65-75% of that number