How to Calculate One-Rep Max for Strength Training

Your one-rep max is the single heaviest weight you can lift for one complete repetition with proper form. It is the gold standard for measuring absolute strength, and knowing your 1RM allows you to set precise training loads, track progress over time, and follow any percentage-based strength program effectively. Whether you are a beginner learning the lifts or an advanced powerlifter peaking for competition, understanding how to calculate and apply your 1RM is fundamental to productive training.

This guide covers the three most popular 1RM estimation formulas, explains when and how to use each one, breaks down training percentage zones, and includes real-world examples for lifters at every level.

What Is One-Rep Max?

One-rep max, abbreviated as 1RM, is the maximum amount of weight a person can lift for a single repetition of a given exercise. It represents peak strength output for that movement pattern. A person who can squat 315 pounds for one rep but not 320 has a squat 1RM of 315 pounds.

The 1RM concept applies primarily to compound barbell exercises such as the squat, bench press, deadlift, and overhead press. These multi-joint movements are the standard benchmarks for measuring upper body, lower body, and total body strength because they engage large muscle groups and allow for heavy loading in a controlled manner.

Why 1RM Matters for Training

Nearly every structured strength training program prescribes loads as a percentage of 1RM. A program that calls for 4 sets of 5 reps at 80% requires you to know your current 1RM for that lift. Without this reference point, you are guessing at how much weight to put on the bar, which leads to either undertrained sessions that fail to stimulate adaptation or overtrained sessions that risk injury and excessive fatigue.

Tracking your 1RM over months and years also provides the most objective measure of strength progress. If your bench press 1RM increases from 185 to 225 pounds over a training cycle, you have clear evidence that your program is working. Subjective feelings about strength are unreliable compared to actual numbers.

One-Rep Max Formulas

Rather than attempting a true maximum lift, which requires careful preparation and carries injury risk, you can estimate your 1RM using a submaximal set. Lift a weight to technical failure at a manageable rep range (3 to 10 reps) and plug the numbers into one of these validated formulas.

The Epley Formula

The Epley formula is the most widely used 1RM estimation equation:

If you bench press 185 pounds for 6 reps, your estimated 1RM is 185 times (1 plus 6 divided by 30) = 185 times 1.20 = 222 pounds. The Epley formula is straightforward, performs well across a wide rep range, and is the default formula used on most gym apps and websites.

The Brzycki Formula

Developed by Matt Brzycki in 1993, this formula uses a different mathematical approach:

Using the same example, 185 pounds for 6 reps: 185 times (36 divided by 31) = 185 times 1.161 = 215 pounds. The Brzycki formula tends to produce slightly more conservative estimates than Epley, especially at higher rep ranges. Many strength coaches prefer it for this reason, as it reduces the risk of overestimating strength and loading the bar with too much weight.

The Lombardi Formula

The Lombardi formula uses an exponential approach:

For 185 pounds at 6 reps: 185 times 6 to the power of 0.10 = 185 times 1.196 = 221 pounds. The Lombardi formula gives results similar to Epley and is sometimes used in research settings.

Formula Comparison

The following table shows estimated 1RM values for a person who lifts 200 pounds at various rep counts:

At 2 to 5 reps, all three formulas produce similar results. Divergence increases above 8 reps, which is why exercise scientists recommend using a weight you can lift for 3 to 5 reps for the most accurate 1RM estimate.

Training Percentage Zones

Once you know your 1RM, you can use percentage-based loading to target specific training adaptations. Each percentage range corresponds to a rep range and training outcome.

These percentages are guidelines, not rigid rules. Individual variation means some lifters can complete more reps than expected at a given percentage, while others complete fewer. After a few training sessions, adjust the percentages to match your actual performance.

Practical Examples

Example 1: Beginner Squatter Building a Foundation

Michael has been squatting for three months and recently completed 135 pounds for 8 reps before his form started breaking down. He wants to calculate his 1RM and set up a training plan.

• Epley formula: 135 x (1 + 8/30) = 135 x 1.267 = 171 pounds
• Brzycki formula: 135 x (36 / (37 - 8)) = 135 x 1.241 = 168 pounds
• Average estimated 1RM: approximately 170 pounds

With an estimated 1RM of 170 pounds, Michael programs his training using hypertrophy percentages to build muscle mass and movement competence. He squats 3 times per week: two sessions at 70% (120 pounds) for 4 sets of 8, and one session at 75% (128 pounds) for 4 sets of 6. After 6 weeks, he retests by doing a heavy set of 5 and recalculates his 1RM to adjust weights upward.

Example 2: Intermediate Bench Press Progression

Aisha has been training for two years and completed 135 pounds for 5 reps on bench press. She wants to build toward a 155-pound single.

• Epley formula: 135 x (1 + 5/30) = 135 x 1.167 = 158 pounds
• Brzycki formula: 135 x (36 / (37 - 5)) = 135 x 1.125 = 152 pounds
• Average estimated 1RM: approximately 155 pounds

Aisha's estimated 1RM of 155 pounds suggests she is already close to her goal. She designs a 4-week peaking program: Week 1 at 80% (125 pounds) for 5x5, Week 2 at 85% (132 pounds) for 5x3, Week 3 at 90% (140 pounds) for 4x2, and Week 4 she attempts 155 pounds for a single after a deload. This structured progression gradually acclimates her nervous system to heavier loads while managing fatigue.

Example 3: Advanced Deadlift Peaking Program

James is a competitive powerlifter with a best deadlift of 500 pounds. He recently pulled 455 for 3 solid reps in training and wants to peak for a 520-pound attempt at a meet in 8 weeks.

• Epley formula: 455 x (1 + 3/30) = 455 x 1.10 = 501 pounds
• Brzycki formula: 455 x (36 / (37 - 3)) = 455 x 1.059 = 482 pounds
• Average estimated 1RM: approximately 492 pounds

The formulas estimate James's current 1RM at roughly 492 pounds, close to his previous best of 500 pounds. To reach 520, he needs an approximately 5% strength increase over 8 weeks. His peaking plan uses a wave-loading approach: Weeks 1 to 3 build volume at 75% to 82%, Weeks 4 to 6 increase intensity to 85% to 92% with reduced volume, Week 7 hits heavy singles at 95% to 97% (475 to 505 pounds), and Week 8 is a deload before the meet. Recalculating his estimated 1RM every 2 weeks helps him confirm he is on track for the 520-pound attempt.

Direct Testing vs. Indirect Estimation

Direct 1RM testing means actually loading the bar with progressively heavier weight until you find the heaviest single you can complete. This method gives you the true number but requires significant preparation and recovery time. A proper 1RM test session involves thorough warm-up sets, strategic weight jumps (typically 5% to 10% increments), adequate rest between attempts (3 to 5 minutes), and a trained spotter for safety.

Indirect estimation using formulas lets you calculate 1RM from a submaximal set without the fatigue and risk of a maximal attempt. The trade-off is reduced precision, typically within 5% of your true 1RM when using 3 to 5 rep sets. For day-to-day training programming, indirect estimation is more practical and just as effective. Reserve direct testing for competition preparation or quarterly strength benchmarks.

Tips for Using Your One-Rep Max

Use conservative estimates for programming. When in doubt, round your estimated 1RM down rather than up. It is far better to train at a slightly lower percentage and complete all prescribed reps with good form than to overshoot and fail sets or compromise technique. Successful completed reps build strength and confidence; failed reps build fatigue and frustration.

Apply progressive overload systematically. Once you can consistently hit the top of your prescribed rep range at a given weight, increase the load by 2.5 to 5 pounds for upper body lifts and 5 to 10 pounds for lower body lifts. This methodical approach, called linear progression, is the most reliable way to build strength over time. Track every set in a training log so you can see your progression and identify when it stalls.

Account for daily readiness. Your 1RM is not a fixed number. Factors like sleep quality, nutrition, stress, and accumulated fatigue all influence how much you can lift on any given day. If your program calls for 85% of 1RM but you feel significantly weaker than usual, reduce the weight by 5% to 10% rather than grinding through poor-quality reps. Training at an appropriate intensity relative to your daily readiness prevents injury and ensures long-term progress.

Periodize your training. Rather than training at the same intensity week after week, cycle through different percentage zones in structured blocks. Spend 3 to 4 weeks building volume at 65% to 75% (hypertrophy), then 3 to 4 weeks increasing intensity to 80% to 88% (strength), then 2 to 3 weeks peaking at 90% to 100%. This periodized approach prevents plateaus and manages fatigue better than constant heavy training.

Common Mistakes to Avoid

• Using high-rep sets to estimate 1RM. Performing 15 or 20 reps to failure and plugging that into a formula produces wildly inaccurate results because muscular endurance, not maximum strength, becomes the limiting factor. Stick to sets of 3 to 5 reps for the most reliable estimates.
• Testing too frequently. True 1RM attempts are taxing on the nervous system and require several days of recovery. Testing every week wastes training time and accumulates unnecessary fatigue. Use indirect estimation for regular tracking and save direct testing for quarterly assessments or pre-competition peaks.
• Ignoring form breakdown. A rep completed with significant form deviation, such as excessive back rounding on deadlifts or bouncing the bar off the chest on bench press, does not count as a valid rep for formula purposes. Only count reps performed with consistent, controlled technique.
• Applying the same 1RM across all exercises. Your 1RM is exercise-specific. A 300-pound squat 1RM tells you nothing about your bench press or deadlift capacity. Calculate and track each major lift independently.
• Not warming up properly before testing. Attempting heavy loads without adequate warm-up sets risks injury and underperformance. A proper warm-up includes 2 to 3 light sets, followed by progressively heavier doubles and singles, with 2 to 3 minutes rest between sets.

Last updated: February 23, 2026