One Rep Max Calculator

You can use it for bench press, squat, deadlift, overhead press, barbell row, or almost any other strength exercise.

The calculator can also help you understand your training weights at different percentages of your estimated 1RM.

What Is a One Rep Max?

A one rep max, usually written as 1RM, is the maximum amount of weight you can lift for one complete repetition with proper form.

For example, if you can bench press 100 kg once but cannot complete 105 kg with good form, your bench press 1RM is around 100 kg.

Your 1RM is different for every exercise.

You may have a:

• Bench press 1RM
• Squat 1RM
• Deadlift 1RM
• Overhead press 1RM
• Barbell row 1RM
• Leg press 1RM

A One Rep Max Calculator estimates this number from a lighter set that you have already completed.

What Is a 1RM Calculator?

A 1RM calculator is a fitness tool that estimates your one-repetition maximum from the weight and reps you can perform.

For example, suppose you bench press:

80 kg × 5 reps

The calculator can use a 1RM formula to estimate your maximum single.

You can then use that estimated number to plan your training weights.

This is useful because you do not have to attempt a very heavy single every time you want to know your approximate strength level.

How to Use the One Rep Max Calculator

Using the calculator is easy.

Step 1: Enter the weight

Enter the weight you lifted during your recent set.

For example:

80 kg

Step 2: Enter your reps

Enter the number of clean repetitions you completed.

For example:

5 reps

Step 3: Calculate your 1RM

Click the calculate button.

The calculator estimates your one rep max.

Step 4: Use the result

You can use the estimated 1RM to calculate different training weights, such as 60%, 70%, 80%, 85%, 90%, or 95% of your maximum.

A good 1RM calculator may show more than one formula because different formulas can give slightly different estimates.

One Rep Max Formula

There are several formulas used to estimate 1RM.

Three common formulas are the Epley, Brzycki, and Lombardi formulas.

Epley Formula

The Epley formula is:

1RM = Weight × (1 + Reps ÷ 30)

For example, if you lift:

80 kg × 5 reps

Then:

1RM = 80 × (1 + 5 ÷ 30)

1RM = 93.33 kg

So your estimated 1RM is about:

93.3 kg

Brzycki Formula

The Brzycki formula is:

1RM = Weight × 36 ÷ (37 − Reps)

Using the same example:

80 kg × 5 reps

The estimated 1RM is about:

90 kg

The Epley and Brzycki formulas may give slightly different answers because they use different mathematical models.

Lombardi Formula

Another commonly used formula is the Lombardi formula:

1RM = Weight × Reps^0.10

It provides another estimate that can be useful when comparing different 1RM formulas.

Why Do Different 1RM Formulas Give Different Results?

A 1RM calculator does not actually know how much weight you could lift for one repetition.

It is making an estimate based on your previous performance.

For this reason, different formulas can produce slightly different results.

For example, one formula may estimate your 1RM at:

90 kg

while another may estimate:

93 kg

That does not mean one calculation is necessarily wrong.

Your actual 1RM can also change depending on:

• Exercise
• Training experience
• Technique
• Fatigue
• Rest
• Sleep
• Fitness level
• Rep range
• How close the set was to failure

This is why a 1RM estimate should be treated as a useful training number rather than an exact measurement.

How Accurate Is a One Rep Max Calculator?

A 1RM calculator gives an estimate, not a guaranteed maximum.

The estimate is generally more useful when it is based on a relatively heavy set with fewer repetitions. Current 1RM calculators commonly recommend using sets in roughly the 1–10 rep range, with lower-rep sets often giving a closer estimate.

For example:

100 kg × 3 reps

will generally provide a more useful 1RM estimate than:

50 kg × 25 reps

because high-repetition performance depends more on muscular endurance and fatigue.

For everyday training, many lifters use a hard set of around 2–6 reps to estimate their 1RM.

Bench Press 1RM Calculator

A bench press 1RM calculator estimates your maximum bench press based on a weight and rep set.

For example:

80 kg × 5 reps

You can enter those numbers into the calculator to estimate your bench press 1RM.

Once you know your estimated bench press 1RM, you can calculate training weights for:

• Strength training
• Powerlifting
• Hypertrophy
• Percentage-based programs
• Workout planning

Your bench press 1RM is specific to the bench press. It should not be used as your squat or deadlift 1RM.

Squat 1RM Calculator

A squat 1RM calculator estimates your maximum squat from a recent set.

For example:

120 kg × 5 reps

The calculator can estimate the weight you might be able to squat for one repetition.

The same basic 1RM formulas can be used for squat, bench press, deadlift, and many other exercises.

Deadlift 1RM Calculator

A deadlift 1RM calculator estimates your maximum deadlift from a sub-maximal set.

For example:

150 kg × 3 reps

can be entered into the calculator to estimate your deadlift 1RM.

You can then use the result to plan your working weights.

Remember that deadlift technique and fatigue can have a large effect on performance, so treat the calculated number as an estimate.

1 Rep Max Percentage Calculator

Knowing your estimated 1RM can help you calculate different training weights.

For example, if your estimated 1RM is:

100 kg

then:

1RM Percentage	Training Weight
100%	100 kg
95%	95 kg
90%	90 kg
85%	85 kg
80%	80 kg
75%	75 kg
70%	70 kg
65%	65 kg
60%	60 kg
50%	50 kg

These percentages are useful for percentage-based training programs.

However, the number of reps you can actually perform at a particular percentage varies from person to person. Percentage charts should therefore be treated as a starting point rather than an exact promise.

How to Calculate Your Training Weight From 1RM

If you know your 1RM, calculating a percentage is simple.

Example

Suppose your 1RM is:

100 kg

You want to train at 80%.

The calculation is:

100 × 80 ÷ 100 = 80 kg

So:

80% of 1RM = 80 kg

Another example:

Your 1RM is 120 kg.

For 75%:

120 × 0.75 = 90 kg

Your training weight would be:

90 kg

1RM Rep Max Chart

A general percentage guide can look like this:

Percentage of 1RM	Common Training Use
95%	Very heavy strength work
90%	Heavy strength work
85%	Strength and strength-hypertrophy
80%	Moderate-heavy training
75%	Moderate training
70%	Higher-volume training
65%	Lighter training
60%	Light training

These are general guidelines. Your actual repetitions at each percentage can be different because everyone has a different strength and endurance profile.

Example: Calculate 1RM From 5 Reps

Suppose you can squat:

100 kg for 5 reps

Using the Epley formula:

1RM = 100 × (1 + 5 ÷ 30)

1RM = 116.7 kg

So your estimated squat 1RM is approximately:

116.7 kg

Now you can calculate training percentages from that number.

For example:

80% = 93.4 kg

85% = 99.2 kg

90% = 105.0 kg

These numbers can help you choose a starting training weight.

Example: Calculate 1RM From 10 Reps

Suppose you can deadlift:

100 kg for 10 reps

Using the Epley formula:

1RM = 100 × (1 + 10 ÷ 30)

1RM = 133.3 kg

This is only an estimate.

As the number of repetitions increases, different formulas can start producing wider differences, so a high-rep set should not be treated as an exact prediction of your true maximum.

Should You Test Your True 1RM?

You do not always need to test your actual one-rep maximum.

For regular training, estimating your 1RM from a hard set can be a convenient option.

A true maximum attempt involves very heavy weight and requires good technique, proper preparation, and appropriate safety precautions.

If you decide to test a true 1RM:

• Warm up properly.
• Use safe equipment.
• Keep your technique controlled.
• Use a spotter when appropriate.
• Do not attempt a maximum lift when seriously fatigued.
• Stop if your form breaks down.

For exercises such as the bench press, having appropriate safety equipment or a qualified spotter is especially important.

What Is an Estimated 1RM?

An estimated 1RM, or e1RM, is a predicted maximum based on your performance at a lighter weight.

For example:

100 kg × 5 reps

might give you an estimated 1RM of around 117 kg using the Epley formula.

You may actually be able to lift 115 kg, 120 kg, or another amount.

The calculator cannot know your exact maximum without testing it.

That is why it is better to use the result as a guide for training.

Benefits of Using a 1RM Calculator

A free 1RM calculator can be useful for several reasons.

No Maximum Attempt Required

You can estimate your strength without immediately attempting your heaviest possible lift.

Easy Workout Planning

You can calculate training weights from a percentage of your estimated 1RM.

Track Strength Progress

If your estimated 1RM increases over time, it can be a useful sign that your strength is improving.

Compare Training Sessions

You can compare your estimated strength from different workouts.

Useful for Different Exercises

The basic formulas can be used for bench press, squat, deadlift, overhead press, and many other lifts.

What Weight Should I Enter?

Enter the weight you actually lifted for the number of repetitions you completed.

Include the total load you lifted according to the unit used by your calculator.

For example, if you bench press:

80 kg for 5 reps

enter:

Weight = 80 kg

Reps = 5

Do not enter the weight you wish you could lift. Use a real recent set.

How Many Reps Should I Use for a 1RM Calculator?

For a useful estimate, a recent hard set of around 1–10 reps is commonly used, with lower-rep sets often providing a tighter estimate.

A practical example is:

3 reps

5 reps

or

6 reps

If you use a very high number of reps, the estimate can become less reliable.

1RM Calculator in KG and LB

A good one rep max calculator should allow you to work in both kilograms and pounds.

For example:

KG: 100 kg

LB: approximately 220.5 lb

You can choose the unit that matches the equipment and workout program you use.

The important thing is to enter the correct weight and keep the unit consistent.

Is 1RM the Same for Every Exercise?

No.

Your 1RM is exercise-specific.

For example, you might have:

Bench press 1RM = 100 kg

Squat 1RM = 140 kg

Deadlift 1RM = 170 kg

These numbers are completely different because the exercises use different muscles, techniques, and movement patterns.

Common 1RM Mistakes

Using a Made-Up Weight

Always enter a real weight from a recent workout.

Using Poor Form

A repetition should be performed with reasonable technique. A poor-form repetition can make the estimate less useful.

Using Too Many Reps

Very high-rep sets can make 1RM estimates less reliable.

Treating the Estimate as Exact

Your calculated 1RM is a prediction, not a guarantee.

Ignoring Fatigue

If you calculate your 1RM after a very hard workout, your performance may be lower than normal.

Frequently Asked Questions

What does 1RM mean?

1RM means one-repetition maximum. It is the heaviest weight you can lift for one complete repetition with proper form.

What is a One Rep Max Calculator?

A One Rep Max Calculator estimates your maximum single-repetition weight using a weight and number of repetitions you have already completed.

How do I calculate my 1 rep max?

Enter the weight you lifted and the number of reps you completed into a 1RM calculator. A formula such as Epley or Brzycki can then estimate your one-rep maximum.

What is the Epley 1RM formula?

The Epley formula is:

1RM = Weight × (1 + Reps ÷ 30)

What is the Brzycki 1RM formula?

The Brzycki formula is:

1RM = Weight × 36 ÷ (37 − Reps)

What is the best 1RM formula?

There is no single formula that is always best for every person and exercise. Epley, Brzycki, Lombardi, and other formulas can produce slightly different estimates. Comparing multiple estimates can give you a more realistic range.

Can I calculate my bench press 1RM?

Yes. Enter your bench press weight and the number of reps you completed to estimate your bench press 1RM.

Can I calculate my squat 1RM?

Yes. A 1RM calculator can estimate your squat maximum from a recent squat set.

Can I calculate my deadlift 1RM?

Yes. Enter your deadlift weight and repetitions to estimate your deadlift 1RM.

Is an estimated 1RM accurate?

It can be a useful training estimate, but it is not guaranteed to match your actual maximum. Accuracy depends on the exercise, number of reps, effort level, technique, and individual strength profile.

How many reps are best for estimating 1RM?

Lower-repetition sets are generally better for estimating 1RM. Many calculators recommend staying within about 1–10 reps, while sets around 2–6 reps are often a practical range for a close estimate.

Should I test my actual 1RM?

You do not need to test your true maximum just to plan normal training. An estimated 1RM can be useful for setting working weights. If you do attempt a true maximum, use proper warm-up, technique, safety equipment, and appropriate supervision.

What is 80% of my 1RM?

Multiply your 1RM by 0.80.

For example, if your 1RM is 100 kg:

100 × 0.80 = 80 kg

So 80% of your 1RM is 80 kg.

What is 90% of my 1RM?

Multiply your 1RM by 0.90.

For example:

100 × 0.90 = 90 kg

So 90% of your 1RM is 90 kg.

Can I use a 1RM calculator for any exercise?

The formulas can be used for many resistance exercises, including bench press, squat, deadlift, overhead press, and other lifts. However, the accuracy of the estimate can vary between exercises and individuals.

Final Thoughts

A One Rep Max Calculator is an easy way to estimate your strength without constantly testing your heaviest possible lift.

Enter your weight and reps, and the calculator can estimate your 1RM using formulas such as Epley, Brzycki, or Lombardi.

You can then use your estimated 1RM to calculate training weights for different percentages.

Whether you want to calculate your bench press 1RM, squat 1RM, deadlift 1RM, or overall strength, CalculatorGuides.com can make the calculation quick and easy.