One Rep Max Calculator
Estimate your one rep max (1RM) using 7 scientific formulas. Get training zone recommendations for strength, hypertrophy, power, and endurance.
Your One Rep Max is the maximum weight you can lift for a single repetition. Most adults can lift 1.5x their bodyweight on deadlift as a beginner.
Calculate your exact 1RM from any rep range below.
Enter Your Lift
Most accurate for 1-10 reps
Why Knowing Your One Rep Max Changes Everything
Walk into any serious gym and you'll hear the question: "What's your max?" Your one rep max (1RM) isn't just a bragging number. It's the foundation that every well-designed training programme is built on.
Here's why it matters. A programme might say "bench press 5 sets of 5 at 75%." Seventy-five percent of what? Your 1RM. Without knowing that number, you're guessing — and guessing leads to either working too light (wasting your time) or too heavy (getting hurt).
The good news: you don't need to actually attempt a maximal lift to know your 1RM. If you can bench 80 kg for 5 reps, or squat 100 kg for 8, this calculator uses that data to estimate what you'd lift for a single rep. It's safer, more practical, and accurate enough to programme your entire training cycle.
How 1RM Formulas Work
The relationship between the weight you can lift and the number of reps you can complete follows a predictable curve. Lift heavier, do fewer reps. Lift lighter, do more. Researchers have modelled this curve into mathematical equations.
Our calculator uses seven peer-reviewed formulas and averages them. Each formula models the weight-to-reps relationship slightly differently:
| Formula | Type | Best For | Accuracy Range |
|---|---|---|---|
| Epley | Linear | General use, 6–10 reps | ±5% for most lifters |
| Brzycki | Linear | Low reps (1–6), most researched | ±3% for low reps |
| Lombardi | Exponential | Conservative estimates | Tends to underestimate |
| Mayhew | Exponential | Research populations | ±5% for trained lifters |
| O'Conner | Linear | Quick estimates | Less accurate at extremes |
| Wathen | Exponential | Higher rep ranges (8–15) | ±5–7% at higher reps |
| Lander | Linear regression | Moderate rep ranges | ±5% for 5–10 reps |
What this means for you: For the most accurate estimate, use a weight you can lift for 3–6 reps. All formulas become less reliable above 10 reps because the relationship between weight and reps gets noisier — fatigue, technique breakdown, and cardiovascular limits start influencing the result more than raw strength.
How to Use Your 1RM for Training
Once you know your 1RM, you can programme your training with precision. Different percentages target different adaptations:
| % of 1RM | Reps | Training Goal | Rest Between Sets |
|---|---|---|---|
| 90–100% | 1–3 | Max strength / peaking | 3–5 minutes |
| 80–90% | 3–5 | Strength building | 2–4 minutes |
| 70–80% | 6–12 | Hypertrophy (muscle growth) | 60–90 seconds |
| 60–70% | 12–15 | Muscular endurance | 30–60 seconds |
| 50–60% | 3–5 (explosive) | Power / speed | 2–3 minutes |
A practical example: If your squat 1RM is 120 kg and you're training for muscle growth, you'd work in the 70–80% range. That's 84–96 kg for sets of 6–12 reps. Our training weight chart above gives you the exact numbers for every percentage.
Most well-designed programmes use a mix of ranges. A typical week might include one heavy day (85–90% for 3–5 reps), one hypertrophy day (70–80% for 8–12 reps), and one lighter technique day (60–70% for higher reps). This approach — called undulating periodisation — builds both strength and size.
How Strong Should You Be? (Strength Standards)
Strength standards give you context for your numbers. These are based on bodyweight multiples for the three main compound lifts, compiled from competitive powerlifting data and large training databases:
| Level | Squat | Bench Press | Deadlift |
|---|---|---|---|
| Beginner (<6 months) | 0.75x bodyweight | 0.5x bodyweight | 1x bodyweight |
| Novice (6–12 months) | 1.25x bodyweight | 1x bodyweight | 1.5x bodyweight |
| Intermediate (1–3 years) | 1.5x bodyweight | 1.25x bodyweight | 2x bodyweight |
| Advanced (3–5 years) | 2x bodyweight | 1.5x bodyweight | 2.5x bodyweight |
| Elite (5+ years) | 2.5x bodyweight | 2x bodyweight | 3x bodyweight |
What this means for you: These standards are for men. Women's standards are typically 60–75% of these values. If you're an 80 kg man who deadlifts 160 kg (2x bodyweight), you're solidly intermediate. Don't compare yourself to gym influencers — compare to these evidence-based benchmarks.
How to Increase Your 1RM Over Time
Your 1RM isn't static — with consistent training, it goes up. The principle behind all strength gains is progressive overload: gradually increasing the demands on your muscles over time.
Add Weight Gradually
Increase by the smallest available increment (typically 2.5 kg / 5 lbs for upper body, 5 kg / 10 lbs for lower body) once you hit the top of your rep range. If your programme calls for 3x8 at 60 kg and you complete all 24 reps with good form, bump to 62.5 kg next session.
Add Reps Before Weight
Can't add weight yet? Add reps. Going from 3x6 to 3x8 at the same weight is still progressive overload. Once you hit the top of your rep range, increase weight and drop reps back down. This "double progression" method is one of the most reliable approaches.
Train the Lift Frequently
Practice makes progress. Benching twice a week consistently beats benching once a week harder. The additional practice improves neural efficiency — your brain gets better at recruiting muscle fibres for the specific movement pattern.
Eat and Sleep Enough
You can't build strength in a large calorie deficit. Eat at maintenance or a slight surplus, get 0.7–1g protein per pound of bodyweight, and sleep 7–9 hours. Muscles grow and strengthen during recovery, not during the workout itself. Check our Protein Calculator for your target.
Realistic expectations: Beginners can expect to add 2.5–5 kg to their main lifts every week for the first 6–12 months. Intermediate lifters progress monthly. Advanced lifters measure gains over months or years. If your 1RM isn't moving, you're either not eating enough, not recovering enough, or need to change your programme.
Safety Tips for Testing and Training Near Your Max
Working with heavy weights carries risk. These guidelines keep you safe whether you're testing your 1RM or training at high percentages:
- Always warm up properly. Start with 5 minutes of light cardio, then work up through progressively heavier sets — 40%, 60%, 75%, 85% of your estimated max — before attempting anything above 90%.
- Use a spotter for bench press, squats, and overhead press. No exceptions. If you train alone, use safety pins set at the right height.
- Stop when form breaks down. A rep completed with bad form doesn't count and risks injury. Your true 1RM is the most you can lift with proper technique, not the most you can move by any means necessary.
- Rest 3–5 minutes between heavy attempts. Your phosphocreatine energy system needs full recovery between maximal efforts. Rushing leads to failed lifts and injury.
- Don't test 1RM often. True max attempts are taxing on your nervous system and joints. Test every 8–12 weeks at most. Between tests, use this calculator with submaximal weights to track progress.
- Never max out when fatigued, sleep-deprived, or fasted. Your strength drops 5–15% without adequate sleep and nutrition. Test when you're fresh, fed, and well-rested.
Common 1RM Estimation Mistakes
Using Too Many Reps
All 1RM formulas lose accuracy above 10 reps. If you enter 15 reps, the estimate might be off by 10–15%. For the most reliable result, use a weight you can lift for 3–6 reps.
Not Going to True Failure
If you enter "5 reps" but could've done 7, the formula underestimates your 1RM. The weight you enter should be one where you completed the stated reps and genuinely could not have done one more with good form.
Assuming All Lifts Scale the Same
The weight-to-reps relationship varies by exercise. Isolation movements (curls, lateral raises) have a flatter curve than compound movements (squat, deadlift). These formulas are most accurate for the big compound lifts.
Treating the Estimate as Exact
Your estimated 1RM has a margin of ±5%. If the calculator says 100 kg, your true max is likely between 95 and 105 kg. Build your training percentages from the estimate, but don't try to hit the exact number on a max attempt.
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How to use this tool
Select your preferred unit system (Imperial or Metric)
Enter the weight you lifted
Select the number of reps you completed (1-15)
Common uses
- Calculating training weights as percentages of your estimated max
- Programming strength, hypertrophy, or power training cycles
- Tracking strength progress over time without maxing out
- Comparing results across 7 peer-reviewed 1RM formulas
- Setting weight targets for specific training zones
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