One Rep Max Calculator

Estimate your one rep max (1RM) using 7 scientific formulas. Get training zone recommendations for strength, hypertrophy, power, and endurance.

Free to use. Runs in your browser.

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

Weight Lifted (lbs)

Repetitions: 5

Most accurate for 1-10 reps

Educational Estimates Only: These calculations are approximations based on population-level formulas and may not accurately reflect your individual health status. Body composition varies significantly due to factors like muscle mass, bone density, hydration, and ethnicity. This is not medical advice. Always consult a qualified healthcare provider for personalized assessment, diagnosis, or treatment decisions.

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 to 10 reps	±5% for most lifters
Brzycki	Linear	Low reps (1 to 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 to 15)	±5 to 7% at higher reps
Lander	Linear regression	Moderate rep ranges	±5% for 5 to 10 reps

What this means for you: For the most accurate estimate, use a weight you can lift for 3 to 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 to 100%	1 to 3	Max strength / peaking	3 to 5 minutes
80 to 90%	3 to 5	Strength building	2 to 4 minutes
70 to 80%	6 to 12	Hypertrophy (muscle growth)	60 to 90 seconds
60 to 70%	12 to 15	Muscular endurance	30 to 60 seconds
50 to 60%	3 to 5 (explosive)	Power / speed	2 to 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 to 80% range. That's 84 to 96 kg for sets of 6 to 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 to 90% for 3 to 5 reps), one hypertrophy day (70 to 80% for 8 to 12 reps), and one lighter technique day (60 to 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 to 12 months)	1.25x bodyweight	1x bodyweight	1.5x bodyweight
Intermediate (1 to 3 years)	1.5x bodyweight	1.25x bodyweight	2x bodyweight
Advanced (3 to 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 to 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 to 1g protein per pound of bodyweight, and sleep 7 to 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 to 5 kg to their main lifts every week for the first 6 to 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 to 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 to 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 to 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 to 15%. For the most reliable result, use a weight you can lift for 3 to 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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Frequently Asked Questions

What is one rep max and why does it matter?

Your one rep max (1RM) is the heaviest weight you can lift for a single repetition with proper form. It matters because every serious training programme prescribes weights as percentages of your 1RM, like '5 sets of 5 at 75%.' Without knowing your 1RM, you're guessing, which leads to training too light or too heavy.

Which 1RM formula is most accurate?

The Brzycki formula is most accurate for low reps (1 to 6), while the Epley formula works better for higher reps (6 to 10). Our calculator averages seven formulas for the most balanced estimate. All formulas lose accuracy above 10 reps, use a weight you can lift for 3 to 6 reps for the best result.

How do I safely test my one rep max?

Warm up with progressively heavier sets (40%, 60%, 75%, 85%), always use a spotter for compound lifts, rest 3 to 5 minutes between attempts, increase in small increments (2.5 to 5 kg), and stop the moment your form breaks down. A rep with bad form doesn't count and risks injury.

How can I improve my one rep max?

Train consistently with progressive overload, add weight or reps each week. Include heavy sessions (85 to 90% for 3 to 5 reps) and hypertrophy sessions (70 to 80% for 8 to 12 reps). Eat enough protein (0.7 to 1g per pound of bodyweight), sleep 7 to 9 hours, and train each lift at least twice per week.

How accurate are 1RM calculators?

Within ±5% when using 3 to 6 reps as input. Accuracy drops with higher reps, a 15-rep set might produce an estimate that's 10 to 15% off. For the most reliable result, use a challenging weight you can lift for no more than 6 reps with good form.

How often should I test my one rep max?

Every 8 to 12 weeks at most. True max attempts are taxing on your nervous system and joints. Between tests, use this calculator with submaximal weights (5 to 8 rep sets) to track your progress without the recovery cost and injury risk of maxing out.

What percentage of 1RM should I train at for muscle growth?

70 to 80% of your 1RM for 6 to 12 reps is the optimal hypertrophy range. This provides enough mechanical tension to stimulate muscle growth while allowing enough volume (total reps) to maximise the growth signal. Rest 60 to 90 seconds between sets.

Is there a difference between estimated and actual 1RM?

Yes. Your estimated 1RM is a mathematical prediction. Your actual 1RM on any given day depends on sleep, nutrition, stress, warm-up quality, and how you're feeling. Think of the estimate as your baseline capability, your actual max might be 5% higher on a great day or 5% lower on a rough one.

Does my 1RM differ between exercises?

Absolutely. You'll have a different 1RM for every exercise. The squat, bench press, and deadlift are the most commonly tracked, but you could calculate 1RM for any resistance exercise. The strength-to-reps relationship varies slightly between compound and isolation movements, the formulas are most accurate for compound lifts.

How much should a beginner be able to lift?

After 3 to 6 months of training, most men can bench 0.5x bodyweight, squat 0.75x, and deadlift 1x bodyweight for a single rep. Women typically reach 60 to 75% of these numbers. These are averages, your starting point depends on genetics, prior activity, and body composition.

What's the difference between 1RM for strength vs. powerlifting?

In general strength training, 1RM is an estimation tool for programming. In competitive powerlifting, it's the actual weight lifted under competition rules (with commands, pauses, and judge approval). Competition maxes tend to be 5 to 10% lower than gym maxes due to stricter form requirements and competition pressure.

Can women use the same 1RM formulas?

Yes. The formulas are based on the universal relationship between weight and reps, they work regardless of sex. Women may find the Epley formula slightly more accurate since it was validated on a mixed-gender population. The only difference is the strength standards used for benchmarking (women's standards are typically 60 to 75% of men's).

Results are for general informational purposes only and should be checked before use. They are not professional advice. See our Disclaimer and Terms of Service.