One Rep Max Calculator
Estimate your one-rep max from the weight and reps you can complete safely. No need to lift to failure.
Estimated one rep max
116.7 kg
Weight for common rep ranges
| Reps | Weight | % of 1RM |
|---|
What is one rep max
One rep max — usually written as 1RM — is the most weight you can lift for a single complete repetition with correct form. It is the gold-standard measure of maximal strength and is used in powerlifting, bodybuilding, and general strength programming.
The Epley formula explained in detail
The Epley formula was published in 1985 by Matt Epley and quickly became the standard for estimating 1RM from lighter sets. It is:
1RM = weight × (1 + reps / 30)
If you lift 100 kg for 5 reps, the formula gives 100 × (1 + 5/30) = 116.7 kg. The formula assumes a roughly linear relationship between load and reps, which works well for compound barbell lifts. It is less reliable above 10–12 reps, where fatigue and endurance begin to blur the 1RM estimate.
How to test 1RM safely
True 1RM testing is risky if you are unprepared. A safer approach is to use submaximal testing: pick a weight you can lift for 2–6 reps with good form, then apply the Epley formula. If you do test a true 1RM, follow these rules:
- Warm up thoroughly with light sets of the target lift.
- Use a spotter or safety bars / pins.
- Choose a weight you can handle for 1–2 reps only.
- Stop if your technique breaks down.
- Limit true 1RM attempts to once every 4–8 weeks.
One rep max standards by level and bodyweight
1RM standards give context but vary by lift, sex, age, and training history. Use them as rough guides rather than rigid targets:
| Level | Relative 1RM (bodyweight ×) | Typical use |
|---|---|---|
| Beginner | 0.75–1.0× | Learning technique |
| Intermediate | 1.0–1.5× | Consistent training 1–3 years |
| Advanced | 1.5–2.0×+ | Competitive or long-term training |
How to use 1RM for programming
Once you know your estimated 1RM, you can set precise training loads:
- Strength: 80–90% of 1RM for 3–5 reps
- Hypertrophy: 65–75% of 1RM for 8–12 reps
- Endurance: 50–65% of 1RM for 12–15+ reps
Pair this with the macro calculator to fuel your sessions and the protein calculator to support recovery.
Other 1RM formulas
Several formulas exist, each with trade-offs:
| Formula | Equation | Notes |
|---|---|---|
| Epley | w × (1 + r/30) | Simple; best for 2–10 reps |
| Brzycki | w × 36 / (37 - r) | Slightly conservative; popular in strength coaching |
| Lombardi | w × r^0.10 | Aggressive; better for power athletes |
| Mayhew | (100 × w) / (52.2 + 41.9 × e^(-0.055 × r)) | Complex; includes body-weight scaling |
For most lifters, the difference between formulas is small. Use Epley for simplicity, or Brzycki if your coach prefers a more conservative estimate.
Using 1RM without lifting to failure
Submaximal testing preserves energy and reduces injury risk. Pick a weight you can move cleanly for 3–6 reps, apply the formula, and use that as your working estimate. Reassess every 4–8 weeks as your strength changes.
Sources and further reading
These independent, authoritative sources inform the methods used on this page.
Frequently asked questions
What is one rep max?
One rep max (1RM) is the maximum amount of weight you can lift for one complete repetition with proper form. It is a key strength benchmark used in powerlifting, weightlifting, and strength training.
How is one rep max calculated?
This calculator uses the Epley formula: 1RM = weight × (1 + reps / 30). It estimates your true 1RM from a submaximal set, so you do not need to lift to failure.
How accurate is the Epley formula?
The Epley formula is reasonably accurate for most people when using 2–10 reps. For very high reps or beginners, the estimate becomes less reliable.
How can I increase my one rep max safely?
Progress gradually with structured programming, prioritize form, include accessory work, and avoid maxing out too frequently. Most programs increase 1RM over weeks and months, not days.
What is a good one rep max for beginners?
Beginner standards vary by lift and body weight. Focus on building a solid technique base first, then use percentage-based programming to increase your 1RM over time.
Should I test my true one rep max?
Testing a true 1RM carries injury risk. Estimating from submaximal reps is safer for most people. If you do test, use a spotter and only after a thorough warm-up.
How often should I calculate my one rep max?
Reassess every 4–8 weeks. Frequent testing can interfere with recovery. Use the calculator to track estimated progress instead of constantly maxing out.
Can one rep max be used for all exercises?
The Epley formula is commonly used for barbell lifts like squat, bench press, and deadlift. For bodyweight or machine exercises, the estimate is less standardized.
What are other 1RM formulas?
Common alternatives include Brzycki (1RM = weight × 36 / (37 - reps)), Lombardi (1RM = weight × reps^0.10), and Mayhew (more complex, uses body weight). Our calculator uses the Epley formula because it is simple and widely accepted.
How do I use 1RM for programming?
Pick rep zones based on goal: 1–3 reps for strength, 8–12 for hypertrophy, 12–15 for endurance. Set working weight as a percentage of 1RM. The <a href='/macro-calculator/'>macro calculator</a> can help you fuel those sessions.