How accurate is this 1RM calculator?

1RM calculators are most accurate when using 3–8 reps. The formulas (Epley, Brzycki, Lombardi, O'Conner, Lander) are validated through research, but individual variation exists. Use the averaged or recommended 1RM for best accuracy, and consider these as estimates rather than absolute values.

How do I convert between kg and lb for 1RM?

The calculator automatically converts between kilograms and pounds. 1 kg = 2.20462 lb. Select your preferred unit in the input form, and all results will display in both units. Your unit preference is saved automatically in your browser.

What is rounding increment and why does it matter?

Rounding increment matches your gym's available weight plates. Most gyms have 2.5 kg or 5 lb plates as the smallest increment. Setting this correctly ensures suggested weights are actually loadable on your barbell. Adjust to 0.5 or 1 if you have microplates available.

What is RIR and should I use it in the calculator?

RIR (Reps In Reserve) indicates how many more reps you could have done. If you stopped at 5 reps but could have done 7, that's RIR 2. Adding RIR adjusts the calculation to account for not going to complete failure, improving estimate accuracy. If you went to absolute failure, use RIR 0 or leave it blank.

How do I use the percentage table for workout programming?

The percentage table shows weights at different intensities (50%–100% of 1RM). Use these for structured training programs. For example, 5x5 programs typically use 80%–85% of 1RM, while hypertrophy work uses 65%–75%. Higher percentages (90%–95%) are for heavy singles or doubles. Lower percentages (50%–65%) work well for speed, technique, or conditioning.

Is it safe to test my 1RM in the gym?

Testing your true 1RM can be safe, but only if you warm up properly and have a spotter, especially for bench press and squat. Max attempts put your body under heavy stress, which increases injury risk. Many lifters use a 1RM calculator to get an accurate estimate without risking a heavy failed rep.

How often should I test my 1RM?

Most lifters check their 1RM every 8–12 weeks. Strength builds slowly, and testing too often can lead to fatigue or poor performance. You can use a calculator anytime you complete a strong working set to estimate your updated 1RM safely.

Should beginners use a 1RM calculator?

Yes. For beginners, it is safer to estimate a 1RM instead of performing a real max attempt. The calculator uses proven formulas to give accurate numbers without pushing your body to failure. Focus on learning proper form and technique before testing heavy singles.

Why do different formulas give different 1RM results?

Each formula was developed using different research studies and athlete groups. Some are better for low reps, some for higher reps, and some for average users. That is why calculators show multiple formulas—your final estimated 1RM is usually a balanced average or recommended value based on all methods.

Can I use 1RM percentages for all exercises?

1RM percentages work best for compound lifts like bench press, squat, and deadlift. They are less accurate for isolation exercises such as bicep curls or tricep extensions, because smaller muscles fatigue faster. Use 1RM charts mainly for big barbell movements and treat other exercises more flexibly.

Free AI 1RM Calculator

Calculate your One-Rep-Max (1RM) using multiple proven formulas. Get accurate strength estimates, training percentages, and progression tracking for bench press, squat, deadlift, and more.

Try an example:

Exercise

Weight Lifted

Unit

Repetitions Performed (Most accurate: 3-8 reps)

RIR - Reps In Reserve (optional)

Athlete Level

Rounding Increment (Match your gym plates)

Previous Known 1RM (optional)

Your Estimated 1RM

Recommended 1RM

- -

⚠️ Accuracy Note

Individual Formula Results

Training Percentages

% of 1RM	Weight	Alt Unit

Suggested Working Set Schemes

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What Is a 1RM? (One Rep Max Explained)

A 1RM (One Rep Max) is the maximum amount of weight you can lift one time with proper form for a specific exercise. It represents your true strength level in lifts like bench press, squat, deadlift, or overhead press.

In simple words: if you load the bar, lift it only once with clean technique, and you cannot complete a second rep, that weight is your one-rep max.

Quick Example: If you can bench press 185 lbs for exactly 1 clean rep, then your bench press 1RM = 185 lbs.

Most lifters, athletes, and coaches in the United States use 1RM to plan safe and effective strength-training programs. Once you know your one-rep max, you can use percentages of it to choose the right weight for your workout.

Measure your current strength level for each major lift.
Set training loads using percentages of your 1RM (like 60%, 75%, or 90%).
Adjust your workouts for strength, muscle gain, or power goals.
Track progress as your one-rep max increases over time.

How to Use This 1RM Calculator Online

Using this free 1RM calculator is quick and straightforward. Just enter one of your recent sets, and the AI tool will estimate your one-rep max (1RM) and give you ready-to-use training numbers. Follow these steps to calculate your 1RM:

1

Select your exercise (Bench Press, Squat, Deadlift, Overhead Press, or Other).
2

Enter the weight lifted and choose your unit (lb or kg).
3

Type how many repetitions you completed (most accurate for 3–8 reps).
4

(Optional) Add your RIR – Reps In Reserve if you did not go all-out.
5

Select your athlete level and set the rounding increment to match your gym plates.
6

(Optional) Enter a previous known 1RM if you want to compare with an older max.
7

Click "Calculate 1RM" to generate your full result breakdown.

After calculation, your result page will show 👇

Feature	What You Get
Estimated 1RM Result Card	Your recommended one-rep max in lb and kg, plus confidence level and athlete category.
Individual Formula Results	1RM values from Epley, Brzycki, Lombardi, O’Conner, and Lander formulas.
Training Percentages Table	A full breakdown of 50%–100% of your 1RM with exact weights in both units.
Suggested Working Set Schemes	Ready-made programs like 5×5 @ 85%, 3×5 @ 87.5%, 3×8 @ 75%, etc., with precise bar weight.
Copy & Print Options	One-click buttons to copy your results or print them for your workout session.

1RM Calculation Methods (Epley, Brzycki, Lombardi & More)

This One Rep Max calculator uses the most trusted strength formulas developed by researchers and coaches. Each method estimates your one-rep max based on the weight you lifted and how many reps you completed. These formulas are widely used in U.S. gyms, powerlifting programs, and athletic training.

All formulas below are included in your result page so you can compare your strength estimates.

Formula Name	1RM Formula	Best Used For
Epley Formula	1RM = Weight × (1 + Reps / 30)	Most accurate for low–medium reps (1–10 reps).
Brzycki Formula	1RM = Weight × (36 / (37 – Reps))	Highly accurate for 3–10 reps.
Lombardi Formula	1RM = Weight × Reps^0.10	Good for higher rep ranges (10+ reps).
O’Conner Formula	1RM = Weight × (1 + 0.025 × Reps)	Best for moderate intensity sets.
Lander Formula	1RM = (100 × Weight) / (101.3 – 2.671 × Reps)	Popular in strength and powerlifting programs.

Each method has its strengths, which is why this calculator shows you all formula results to give you a more reliable and well-rounded estimate of your true 1RM.

Bench Press 1RM Calculator

This Bench Press 1RM Calculator helps you estimate your maximum bench press strength using science-backed formulas. Just enter the weight you lifted and how many reps you completed — the tool will calculate your one-rep max (1RM) along with training percentages and recommended working sets.

The bench press measures upper-body pushing strength, especially the chest, shoulders, and triceps. Most accurate results come from sets in the 3–8 rep range.

Great for powerlifting, bodybuilding, and strength tracking.
Shows your estimated 1RM in lb and kg.
Includes Epley, Brzycki, Lombardi, O’Conner & Lander calculations.
Comes with a bench-press–specific training percentage table.

Squat 1RM Calculator

This Squat 1RM Calculator estimates your maximum back squat strength using proven formulas used by lifters and strength coaches. Enter your weight and reps, and the tool will instantly calculate your one-rep max.

The squat is a full-body strength lift, targeting the legs, glutes, core, and lower back. For best accuracy, use a set done with 3–6 reps.

Perfect for powerlifting and athletic strength programs.
Displays 1RM in both lb and kg.
Shows results from 5 trusted squat calculation formulas.
Includes a squat-specific percentage chart for strength training.

Deadlift 1RM Calculator

The Deadlift 1RM Calculator helps you determine your true deadlift strength without performing a risky max attempt. Enter your working weight and reps to get an accurate 1RM estimation.

The deadlift trains your entire posterior chain — hamstrings, glutes, lower back, upper back, and grip. Most accurate when using sets of 2–6 reps.

Ideal for powerlifters and strength athletes tracking progress.
Shows 1RM in lb and kg instantly.
Calculates using Epley, Brzycki, Lombardi, O’Conner, and Lander methods.
Includes deadlift training percentages for strength and power workouts.

How to Calculate Your 1RM Manually

If you don’t want to use a calculator, you can still estimate your one-rep max (1RM) manually using proven strength formulas. These equations were developed by researchers and coaches to predict your maximum lift based on weight and reps.

Manual formulas are most accurate when the set is performed for 3–8 clean reps.

Here are the most reliable ways to calculate your 1RM by hand:

1

Epley Formula:
1RM = Weight × (1 + Reps / 30)
2

Brzycki Formula:
1RM = Weight × (36 / (37 – Reps))
3

Lombardi Formula:
1RM = Weight × Reps^0.10
4

O’Conner Formula:
1RM = Weight × (1 + 0.025 × Reps)

While these manual formulas work well, they still provide an estimate — not a perfect number. That’s why many lifters prefer using a dedicated 1RM calculator which applies all formulas together for a more balanced result.

How Accurate Are One Rep Max Calculators?

One Rep Max calculators are generally very accurate when used correctly—especially for sets performed in the 3–8 rep range. These tools are built on research-backed formulas tested on thousands of lifters, making them a reliable way to estimate your 1RM without doing a risky all-out max attempt.

For most people, a good 1RM calculator is 90–95% accurate when reps and form are consistent.

What affects the accuracy of a 1RM calculator?

1

Reps performed: Best accuracy happens with 3–8 reps. Very high reps (12–20) or extremely low reps (1–2) can reduce accuracy.
2

Form quality: If your reps are sloppy or inconsistent, the estimate becomes less reliable.
3

Fatigue and rest: If you performed many sets beforehand, your strength set won’t reflect your true potential.
4

Exercise type: Calculators are most accurate for compound lifts like Bench Press, Squat, and Deadlift—less accurate for isolation lifts.

While no calculator can match a perfectly executed real 1RM test, they provide a safe, fast, and highly reliable estimate—making them ideal for everyday gym training and program planning.

1RM Percent Training Chart (Strength, Hypertrophy & Power)

Once you know your one-rep max (1RM), you can use different percentages of that number to train for strength, muscle growth (hypertrophy), and power. This 1RM percentage chart helps you choose the right weight, reps, and sets for your workout goal.

Example: If your squat 1RM is 300 lb, then 75% of 1RM is 225 lb. Your 1RM calculator automatically generates these numbers for you.

1RM Training Zones Chart 👇

Goal	% of 1RM	Reps / Set	Typical Sets	Notes
Max Strength	80–90% of 1RM	3–6 reps	3–6 sets	Heavy lifting to build pure strength. Longer rest (2–4 minutes).
Hypertrophy (Muscle Growth)	65–80% of 1RM	6–12 reps	3–5 sets	Best zone for muscle size. Moderate rest (60–120 seconds).
Power (Explosiveness)	60–80% of 1RM	1–5 reps	3–6 sets	Move the weight fast and explosive. Focus on bar speed, not fatigue.
Strength Endurance / Volume	50–65% of 1RM	10–20 reps	2–4 sets	Great for high-rep work, conditioning, and technique practice.

Your 1RM calculator automatically converts these training zones into exact bar weights so you don’t have to do the math every time you train.

Free AI 1RM Calculator