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What Is Your 1RM and Why Estimate It?

A one-repetition maximum (1RM) is the heaviest weight an individual can lift for a single repetition with correct form. This is used to calculate weight for different training goals. For example, to develop strength, weight should be 80–100% of your 1 repetition maximum.

The Role of 1RM in Strength Training

A one-repetition maximum plays an important role in strength training, determining the percentage of maximum resistance to promote muscle growth and enhance strength.

For example, the recommended range for building muscle is 8–12 repetitions at 60–80% of your 1RM.

If a person has a bench press 1RM of 80 kg, 60–80% is approximately 48–64 kg. This is the ideal weight to perform the above repetition range for muscle growth.

Why Women Over 40 Should Estimate, Not Test

Estimating and not testing the 1RM for women is a safe and easy way to determine maximum strength without the danger of performing the movement.

Women over 40 who intend to lift for strength can perform a 1RM to determine maximal strength. However, it is not mandatory for those who are pursuing other training goals, such as hypertrophy and endurance.

Bench Press 1RM Calculator — Inputs and Outputs

The bench press 1RM calculator for women considers the following factors, such as units, weight lifted, and repetition completed, to determine your 1RM. Below, we discuss these key inputs and the expected outputs to highlight how the calculator functions.

Inputs: weight lifted and reps completed (ideal: 2–10 reps)

• Units: Select metric or imperial
• Weight Lifted: Total amount of weight lifted, reflecting the load your muscle must overcome.
• Repetitions Completed: Capture the volume and intensity, identifying how close the effort is to muscle fatigue. This is ideal for 2-10 repetitions.

Outputs: estimated 1RM and key strength zones (e.g. 70–85%)

• Estimated 1RM: The maximum amount of weight you can lift with correct technique.
• Key Strength Zones: Highlights different weights and percentages required for specific training outcomes, including strength, hypertrophy, and endurance.

How the 1RM Estimation Works

The bench press calculator for women uses the Epley and Brzycki formulas to estimate your 1RM.

Epley and Brzycki Formulas (Most Common)

The Epley formula and Brzycki formula are the most commonly used to estimate your 1RM.

These formulas allow you to determine your 1RM from a submaximal load (the weight you can lift for multiple repetitions), allowing you to train safely without testing your true max.

Epley Formula

• 1RM = Weight x (1 + 0.0333 x Reps)

Example

If you lifted 65 kg for 8 repetitions:

• 65 kg x (1 + 0.0333 + 8 repetitions) =
• 65 x 1.2664 = 82 kg

Suitable for:

• Moderate to higher reps (up to 10).
• General fitness and hypertrophy training.

Brzycki Formula

• 1RM = Weight ÷ (1.0278 - 0.0278 x Reps)

Example

• 50 kg ÷ (1.0278 - 0.0278 x 8) =
• 50 ÷ 0.8054 = 62 kg

Suitable for

• Lower rep ranges (10 or fewer).
• Strength-focused training where accuracy near max load matters.

Accuracy Considerations by Rep Range

The following accuracy considerations are to be expected by the repetition range.

• The best range for accuracy is 2-8 repetitions, presenting a balance of load, technique, and fatigue.
• When repetition surpasses 10, fatigue and endurance distort strength.

Safe Testing Tips for Midlife Lifters

Maintaining safety when testing your 1RM is essential for midlife lifters. Below, we share tips, including using a spotter, Smith machine, warm-ups, rest, and recovery, to help you determine your 1RM safely.

Submax Reps with Spotter or Smith Machine

Performing your test using sub-maximal repetitions means the weight is lighter, reducing the risk of injury. This is ideal for beginners and those who want to determine their 1RM without pressing maximum weight, while reducing the risk of injury.

Additionally, perform the lift with a Smith machine or with the help of a spotter. The Smith machine utilizes guided rails and safety hooks, allowing you to rack the bar at any time. Meanwhile, a spotter remains on standby to assist and lift the bar in the event of failure.

Rest, Warm-Up, and Recovery Between Attempts

Warming up and allowing for rest between attempts not only improves safety but also performance.

Before your attempt, we recommend performing a warm-up to prepare your muscles and joints for the test. This should include:

• Light Cardio: 3 minutes on treadmill or elliptical. This increases blood flow to working muscles and warms up muscles and joints.

• Dynamic Stretches: Perform dynamic arm swings and arm circles. Sources indicate this will lengthen muscle tissue, promoting flexibility and joint mobility.

• Perform Warm-up Sets: Prepares muscles for maximal effort. This should include:
  • Set 1: 5–10 repetitions with 50% of your 1RM.
  • Set 2: 4–6 repetitions with 60% of your 1RM.
  • Set 3: Perform your test.

• Rest: Perform with a 1–2 minute rest between each set. Studies show that a 120-second rest period helps to maintain muscle function and perform the total number of repetitions for each set. This will allow your muscles to recover and push with greater effort in the following set.

Using Your Estimated 1RM in a Program

Now that you have determined your 1RM, you can begin applying it to your training programs to pursue your goals. Below, we discuss different training zones and how to adjust volume and load for joint health.

Training Zones for Strength, Muscle, or Maintenance

Determining your 1RM can help you with programming your training goals. Sources indicate these load recommendations for the following goals.

• Strength: 1–5 repetitions (85–100% of 1RM maximum)
• Hypertrophy: 8–12 repetitions (75–85% of 1RM maximum)
• Endurance: 12–15+ repetitions (below 60% of 1RM maximum)

For maintenance, we recommend performing within the 8–12 repetition range for hypertrophy without progressively overloading (increasing weight, sets, or repetitions). This will enable you to maintain muscle mass.

Adjusting Volume and Load for Joint Health

Strength training is excellent for joint and muscle health; however, greater loads can stress joints. This can be avoided by reducing training volume and joint health using the following methods:

• Deload Weeks: Weeks where you perform the same program with 50% of your 1RM at the same intensity. This helps consolidate your lifts and supports joint and tissue health.

• Utilize Hypertrophy and Endurance: Programming with both repetition ranges allows you to get the benefits of heavier resistance training while reducing joint stress with lower-weighted exercises.

• Reduce Load for Injured Joints: Consider reducing resistance for injured joints and focusing on performing corrective exercise and completing your working sets with correct technique.

Example Estimates (See How It Works)

Here are some examples of equations to illustrate how equations work. Below, we use both equations for each example to compare formulas. Each will be listed with the 1RM and 70%, 80%, and 90% of the 1RM.

6 reps × 40 kg — Estimated 1RM

This example contains 6 repetitions, meaning it is better suited to the Epley formula.

Epley Formula

• 1RM = Weight x (1 + 0.0333 x Reps)
• 40 kg x (1 + 0.0333 x 6)
• 40 x 1.1998 = 48 kg

From 1RM 48 kg:

• 70% of 48 kg = 33.6 kg
• 80% of 48 kg = 38.4 kg
• 90% of 48 kg = 43.2 kg

Brzycki Formula

• 1RM = Weight ÷ (1.0278 - 0.0278 x Reps)
• 40 ÷ (1.0278 - 0.0278 x 6)
• 40 ÷ 0.861 = 46.5 kg

From 1RM 46.5 kg:

• 70% of 46.5 kg = 32.55 kg
• 80% of 46.5 kg = 37.20 kg
• 90% of 46.5 kg = 41.85 kg

3 reps × 50 kg — Compare Formulas

This example contains 3 repetitions, meaning both Epley and Brzycki formulas are suitable.

Epley Formula

• 1RM = Weight x (1 + 0.0333 x Reps)
• 50 kg x (1 + 0.0333 x 3)
• 50 x 1.0999 = 55 kg

From 1RM 55 kg:

• 70% of 55 kg = 38.5 kg
• 80% of 55 kg = 44 kg
• 90% of 55 kg = 49.5 kg

Brzycki Formula

• 1RM = Weight ÷ (1.0278 - 0.0278 x Reps)
• 50 kg ÷ (1.0278 - 0.0278 x 3)
• 50 kg ÷ 0.9444 = 53 kg

From 1RM 53 kg:

• 70% of 53 kg = 37.1 kg
• 80% of 53 kg = 42.4 kg
• 90% of 53 kg = 47.7 kg

When and How to Re-Test

Re-testing is important to ensure you are tracking, progressing, and continually challenging yourself. Below, we explore when and how to re-test to help you progress toward your strength training goals.

Re-estimate Every 8–12 Weeks or After Progress

We recommend re-estimating your 1RM every 8–12 weeks or after noticeable changes to your strength levels

Re-testing after an 8–12 week training block means you have sufficient time to progressively overload your bench press and increase strength.

However, if you are noticing strength increases during this training where you are increasing the weight, sets, or repetitions, then consider re-testing.

Source

1. Sople, D. & Wilcox, R.B. III. (2025). Dynamic warm-ups play pivotal role in athletic performance and injury prevention. Arthroscopy, Sports Medicine, and Rehabilitation, 7(2), 101023. https://doi.org/10.1016/j.asmr.2024.12.015. https://www.sciencedirect.com/science/article/pii/S2666061X24001664
2. Matos F, Ferreira B, Guedes J, Saavedra F, Reis VM, Vilaça-Alves J. Effect of Rest Interval Between Sets in the Muscle Function During a Sequence of Strength Training Exercises for the Upper Body. J Strength Cond Res. 2021 Jun 1;35(6):1628-1635. doi: 10.1519/JSC.0000000000002941. PMID: 34027921.https://pubmed.ncbi.nlm.nih.gov/34027921/
3. Schoenfeld BJ, Grgic J, Van Every DW, Plotkin DL. Loading Recommendations for Muscle Strength, Hypertrophy, and Local Endurance: A Re-Examination of the Repetition Continuum. Sports (Basel). 2021 Feb 22;9(2):32. doi: 10.3390/sports9020032. PMID: 33671664; PMCID: PMC7927075. https://pmc.ncbi.nlm.nih.gov/articles/PMC7927075/

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