How the 1RM Calculator Works

To use our 1RM calculator, follow these steps:

Pick a weight that is a reasonable challenge for you.
After a brief warm-up (remembering to stretch), lift that weight as many times as you can.
When you reach muscular failure (the point when your working muscle is fatigued to the extent that it can no longer complete another repetition of a movement), put the bench press bar away.
Enter the weight you lifted and the number of reps into the calculator.
Read your one-rep max from the results section.

You'll notice how much easier it is to use the bench press calculator instead of just trying to lift a weight that you suppose is close to your max bench weight. Using a calculator eliminates the guesswork and the risk of injury due to overestimation.

Extra Tip

Try to lift enough weight to accomplish 6-8 reps. Record the weight and how many reps you managed to do in our bench press calculator. Then, knowing the 1 rep max, try lifting 90% of your 1RM.

Example: If you lift 80 kg for 8 reps, your estimated 1RM is 102 kg according to our calculator. Next time, you should try to lift 91 kg (90% of your 1RM) and record how many reps you manage. Enter the new data into the calculator for a more accurate estimate of your max bench press.

The Max Bench Calculator Formula

The formula for calculating your 1-rep max (1RM) uses the following variables:

\( 1RM \) – One-rep max (the estimated max weight you can lift once).
\( w \) – Weight lifted.
\( r \) – Number of repetitions performed.

To calculate the 1RM, use the **Epley formula**, which is one of the most commonly used equations:

\[ 1RM = w \times \left(1 + \frac{r}{30} \right) \]

This is a submaximal method for estimating your one-rep max. Since it is only a prediction, it may slightly overestimate or underestimate your true 1RM depending on factors like fatigue, muscle composition, and training experience.

However, this formula provides a reliable starting point, especially for athletes looking to track progress and structure effective training programs.

Example

Calculating Your One-Rep Max (1RM)

Your **one-rep max (1RM)** is the maximum weight you can lift for a single repetition. It is a key measure of strength and helps design effective training programs by determining appropriate weight percentages for different workout intensities.

The general approach to calculating 1RM includes:

Identifying the weight you lifted for a specific number of reps.
Using a formula to estimate your maximum possible single rep lift.
Applying 1RM to determine training intensities for strength, endurance, or hypertrophy.

1RM Estimation Formula

One of the most widely used formulas for estimating 1RM is the **Epley Formula**:

\[ 1RM = W \times (1 + \frac{R}{30}) \]

Where:

W is the weight lifted (in pounds or kilograms).
R is the number of repetitions performed.

Example:

If you bench press **100 lbs** for **5 reps**, your estimated 1RM is:

Step 1: Plug values into the formula: \( 1RM = 100 \times (1 + \frac{5}{30}) \)
Step 2: Solve: \( 1RM = 100 \times 1.1667 = 116.67 \) lbs.

Alternative 1RM Formula: Brzycki Equation

Another commonly used method is the **Brzycki Formula**:

\[ 1RM = \frac{W}{1.0278 - (0.0278 \times R)} \]

Example: If you lift **150 lbs** for **6 reps**:

Step 1: Plug values into the formula: \[ 1RM = \frac{150}{1.0278 - (0.0278 \times 6)} \]
Step 2: Solve: \( 1RM = 174.87 \) lbs.

Using 1RM for Training

Once you calculate your 1RM, you can use percentages of it to structure your training:

Strength Training: 85-100% of 1RM (1-5 reps per set)
Muscle Growth (Hypertrophy): 65-85% of 1RM (6-12 reps per set)
Endurance Training: 50-65% of 1RM (12+ reps per set)

Real-life Applications of 1RM

Knowing your 1RM helps in various ways, such as:

Tracking progress over time and setting new personal records.
Designing effective weightlifting programs for strength and hypertrophy.
Preventing overtraining by using appropriate weight percentages for workouts.

Common Units for 1RM

Weight Units: 1RM is commonly measured in pounds (lbs) or kilograms (kg).

Percentage-Based Training: Most workout programs use percentages of 1RM to determine intensity levels for different training goals.

Common Training Approaches Based on 1RM

Progressive Overload: Gradually increasing weight to improve strength.

Deloading: Lowering intensity periodically to prevent overtraining.

Periodization: Structuring training cycles with varying intensity and volume.

Bench Press 1RM Calculation Examples Table
Problem Type	Description	Steps to Solve	Example
Calculating 1RM Using the Epley Formula	Estimating your one-rep max (1RM) based on weight lifted and reps performed.	Identify the weight lifted \( W \) and the number of reps \( R \). Use the formula: \[ 1RM = W \times (1 + \frac{R}{30}) \]	If you bench press 100 lbs for 5 reps, \[ 1RM = 100 \times (1 + \frac{5}{30}) = 116.67 \text{ lbs} \]
Calculating 1RM Using the Brzycki Formula	Another common formula for estimating 1RM based on reps performed.	Use the Brzycki equation: \[ 1RM = \frac{W}{1.0278 - (0.0278 \times R)} \]	If you lift 150 lbs for 6 reps, \[ 1RM = \frac{150}{1.0278 - (0.0278 \times 6)} = 174.87 \text{ lbs} \]
Finding Your Training Weight	Using a percentage of your 1RM to determine optimal weight for training.	Decide on the intensity level (e.g., 75% of 1RM for strength training). Multiply 1RM by the chosen percentage.	If your 1RM is 200 lbs and you train at 75%, \[ Training \, Weight = 200 \times 0.75 = 150 \text{ lbs} \]
Real-life Applications	Applying 1RM calculations to strength training and progression.	Track progress and adjust weights accordingly. Use 1RM to set training goals for different rep ranges.	If a lifter’s 1RM improves from 180 lbs to 200 lbs, their strength has increased, allowing them to lift heavier in training.