Free One Rep Max Calculator
Estimate your one-rep max (1RM) for any exercise without actually maxing out. Get training percentages and rep range recommendations.
What Is a One Rep Max (1RM)?
Your one rep max (1RM) is the maximum amount of weight you can lift for a single repetition with proper form. It's the gold standard measurement of maximal strength for any given exercise.
Knowing your 1RM is essential for effective strength training because it allows you to:
- Program training loads — Most programs prescribe weights as percentages of your 1RM
- Track progress — Compare your 1RM over time to measure strength gains
- Set realistic goals — Know where you are to plan where you're going
- Ensure appropriate intensity — Too light doesn't stimulate growth; too heavy risks injury
1RM Formulas Explained
Several research-backed formulas can estimate your 1RM from a multi-rep set. Each works slightly differently:
Epley Formula (Most Common)
1RM = Weight × (1 + Reps/30) Simple and widely used. Tends to slightly overestimate at high rep ranges.
Brzycki Formula
1RM = Weight × (36 / (37 - Reps)) Accurate for 1-10 reps. Produces more conservative estimates than Epley.
Lombardi Formula
1RM = Weight × Reps^0.10 Uses an exponential approach. Good for moderate rep ranges.
Mayhew Formula
1RM = (100 × Weight) / (52.2 + 41.9 × e^(-0.055 × Reps)) More complex formula, developed from bench press research.
O'Conner Formula
1RM = Weight × (1 + 0.025 × Reps) Simple linear formula. Conservative at higher rep ranges.
Wathen Formula
1RM = (100 × Weight) / (48.8 + 53.8 × e^(-0.075 × Reps)) Exponential formula, tends to be conservative.
Lander Formula
1RM = (100 × Weight) / (101.3 - 2.67123 × Reps) Linear formula, becomes inaccurate above 10 reps.
Which Formula Should I Use?
For most purposes, the average of multiple formulas gives the most reliable estimate. Our calculator does this automatically. If you must choose one:
- Brzycki — Best for 1-6 reps, conservative estimates
- Epley — Good all-around, slightly higher estimates
- For high reps (10+) — All formulas become less accurate; use caution
How Accurate Are 1RM Estimates?
1RM calculations are generally accurate within ±5% for 3-10 reps. Accuracy decreases as rep count increases:
| Rep Range | Accuracy | Notes |
|---|---|---|
| 1-3 reps | ±3% | Most accurate; closest to actual 1RM |
| 4-6 reps | ±5% | Very reliable for programming |
| 7-10 reps | ±7% | Good for general programming |
| 11-15 reps | ±10-15% | Less reliable; endurance becomes a factor |
| 15+ reps | ±15-20%+ | Not recommended for 1RM estimation |
Why Estimates Can Be Off
- Fiber type — "Rep monsters" (slow-twitch dominant) can do more reps at a given percentage than "power types" (fast-twitch dominant)
- Training history — Endurance athletes may underestimate their max; powerlifters may overestimate
- Technique — Inefficient technique affects multi-rep sets more than singles
- Fatigue state — Formulas assume you're fresh; cumulative fatigue skews results
- Psychology — Grinding out a heavy single requires different mental skills than rep work
Training Percentages Explained
Once you know your 1RM, you can calculate training weights for different goals:
Reps: 1-5 per set
Rest: 3-5 minutes
Effect: Maximal strength, neural adaptations, minimal hypertrophy
Best for: Powerlifters, peaking phases, strength athletes
Reps: 6-12 per set
Rest: 60-90 seconds
Effect: Muscle growth, moderate strength gains
Best for: Bodybuilders, general fitness, muscle building
Reps: 12-20+ per set
Rest: 30-60 seconds
Effect: Muscular endurance, metabolic conditioning
Best for: Endurance athletes, circuit training, conditioning
Strength Standards
How does your lift compare to others? These standards are based on body weight ratios for the main compound lifts:
Bench Press Standards (Male)
| Level | BW Ratio | Example (180 lb person) |
|---|---|---|
| Beginner | 0.50× BW | 90 lbs |
| Novice | 0.75× BW | 135 lbs |
| Intermediate | 1.00× BW | 180 lbs |
| Advanced | 1.50× BW | 270 lbs |
| Elite | 2.00× BW | 360 lbs |
Squat Standards (Male)
| Level | BW Ratio | Example (180 lb person) |
|---|---|---|
| Beginner | 0.75× BW | 135 lbs |
| Novice | 1.00× BW | 180 lbs |
| Intermediate | 1.50× BW | 270 lbs |
| Advanced | 2.00× BW | 360 lbs |
| Elite | 2.50× BW | 450 lbs |
Deadlift Standards (Male)
| Level | BW Ratio | Example (180 lb person) |
|---|---|---|
| Beginner | 1.00× BW | 180 lbs |
| Novice | 1.25× BW | 225 lbs |
| Intermediate | 1.75× BW | 315 lbs |
| Advanced | 2.25× BW | 405 lbs |
| Elite | 3.00× BW | 540 lbs |
When to Test Your Actual 1RM
While estimated 1RM is sufficient for most training purposes, there are times when testing a true max is appropriate:
Good Reasons to Test
- Powerlifting/weightlifting competition preparation
- End of a peaking cycle
- Personal milestone goals (1000 lb total, 2× BW squat, etc.)
- Verifying estimates before a new training cycle
How to Test Safely
- Warm up thoroughly — 10-15 minutes of general warm-up, then progressive loading
- Use a spotter — Essential for bench press, recommended for all lifts
- Follow a warm-up protocol:
- Bar × 10
- 50% × 5
- 70% × 3
- 85% × 1
- 92% × 1
- 100% × 1 (attempt)
- Don't jump more than 5-10% above your previous max
- Know when to stop — If form breaks down, terminate the attempt
- Rest 3-5 minutes between heavy singles
How to Increase Your 1RM
Building maximal strength requires specific training approaches:
Progressive Overload
Gradually increase weight, reps, or sets over time. Add 2.5-5 lbs to upper body lifts and 5-10 lbs to lower body lifts when you hit all prescribed reps.
Specificity
To get better at heavy singles, practice heavy singles (carefully). Include work at 85%+ of your max regularly, not just light weight for reps.
Eat Enough
Strength gains are limited when under-eating. Ensure adequate calories and especially protein (0.8-1g per pound) to support recovery and adaptation.
Recover Properly
Sleep 7-9 hours nightly. Don't train the same lift to max intensity multiple times per week. Recovery is when adaptation happens.
Perfect Your Technique
Efficient technique lets you lift more weight safely. Record yourself, get coaching, and practice movement quality at lower weights.
Use Periodization
Cycle through phases: hypertrophy (higher reps), strength (moderate reps), peaking (low reps). This prevents plateaus and manages fatigue.
Frequently Asked Questions
Everything you need to know about one rep max calculations
What is a one rep max (1RM)?
A one rep max (1RM) is the maximum amount of weight you can lift for a single repetition with proper form. It's the gold standard for measuring maximal strength in a specific exercise and is used to program training loads as percentages of your max.
How do I calculate my 1RM without actually maxing out?
Use a 1RM calculator by entering a weight you can lift for multiple reps (ideally 3-10 reps). The calculator applies formulas like Epley or Brzycki to estimate your max. For example, if you bench 185 lbs for 8 reps, your estimated 1RM is approximately 230 lbs.
Which 1RM formula is most accurate?
The Epley and Brzycki formulas are most commonly used and tend to be accurate within 5% for most people when using 3-10 reps. For higher rep ranges (10+), accuracy decreases. The best approach is to use the average of multiple formulas.
How many reps should I use to estimate my 1RM?
Use a weight you can lift for 3-10 reps with good form. Lower rep ranges (3-5) tend to give more accurate estimates. Using 12+ reps significantly reduces accuracy because the formulas weren't designed for high-rep sets and fatigue becomes a major factor.
What percentage of 1RM should I train at?
Training percentages depend on your goals: Strength (85-100% for 1-5 reps), Hypertrophy (65-85% for 6-12 reps), Muscular Endurance (50-65% for 12-20+ reps). Most programs cycle through different percentages for well-rounded development.
How often should I test or recalculate my 1RM?
Recalculate your estimated 1RM every 4-8 weeks, or whenever you complete a training cycle. Actual max testing should be done sparingly (every 3-6 months) because it's fatiguing and carries higher injury risk. Estimated 1RM is sufficient for programming.
Is it safe to test my actual 1RM?
Testing a true 1RM carries higher injury risk than submaximal training. If you do test, warm up thoroughly, use a spotter, ensure proper form, and don't attempt weights more than 5-10% above your previous max. For most people, estimated 1RM is safer and sufficient for programming.
Why is my actual 1RM different from the calculated estimate?
1RM formulas are estimates based on population averages. Your actual max can differ due to: training history (strength vs endurance background), fast-twitch vs slow-twitch muscle fiber ratio, neural efficiency, and psychological factors. Some people are 'rep monsters' while others excel at maximal lifts.
Does 1RM differ between exercises?
Yes, you have a different 1RM for each exercise. Strength isn't universal — your bench press 1RM tells you nothing about your squat 1RM. Calculate separately for each lift you want to program, typically focusing on the main compound movements.
What's a good 1RM for my body weight?
Strength standards vary by exercise. For bench press, beginner is 0.5x bodyweight, intermediate is 1x, advanced is 1.5x, and elite is 2x+. For squat and deadlift, multiply these numbers by approximately 1.25-1.5x. Gender, age, and training experience also affect standards.
References
- Brzycki M. Strength testing—predicting a one-rep max from reps-to-fatigue. JOPERD. 1993;64(1):88-90.
- Epley B. Poundage chart. Boyd Epley Workout. Lincoln, NE. 1985.
- LeSuer DA, McCormick JH, et al. The accuracy of prediction equations for estimating 1-RM performance in the bench press, squat, and deadlift. J Strength Cond Res. 1997;11(4):211-213.
- Mayhew JL, Ball TE, et al. Prediction of 1 repetition maximum in bench press from repetitions to fatigue. J Sports Med Phys Fitness. 1992;32(4):370-376.