One-Rep Max (1RM) Calculator

Estimate your maximum lifting strength for any exercise.

Weight Lifted (for reps)

Repetitions Performed Must be 2 reps or more.

1RM Formula

Your Max Strength Estimate

Estimated 1RM (Max)

Result using Epley Formula

Strength Interpretation

The result represents the maximum weight you can lift once.

Estimating Your One-Rep Max (1RM) for Strength Goals

The **One-Rep Max (1RM) Calculator** estimates the heaviest weight you can theoretically lift for one repetition across any lift (e.g., squat, bench press, deadlift). Calculating your **1RM** is fundamental for setting effective **strength goals**, periodization in training, and optimizing load for hypertrophy (muscle growth). By avoiding the actual heavy single lift, you minimize the risk of injury while maximizing **strength gains** planning.

The Epley Formula and Accuracy

This calculator offers several reliable **1RM formulas**, with the **Epley formula** being the most popular due to its simplicity and high correlation with actual max lifts for rep counts under 10:

$$\text{1RM} = \text{Weight} \times \left(1 + \frac{\text{Reps}}{30}\right)$$

Other formulas like **Brzycki** and **Lander** provide slightly different estimates based on their specific mathematical models, but they all use the same inputs: the **weight lifted** and the **repetitions performed**. Using a weight that allows you to perform between $2$ to $10$ reps generally yields the most accurate **1RM estimate**.

Using Your 1RM for Effective Training

Once you know your **max lifting weight**, you can easily calculate the percentages needed for various training objectives:

**Hypertrophy (Muscle Growth):** Typically $60$-$75\%$ of your **1RM**.
**Strength:** Typically $80$-$95\%$ of your **1RM**.
**Endurance:** Typically $\leq 60\%$ of your **1RM**.

The **1RM calculator** transforms your training from guesswork into a precise, calculated approach for achieving consistent **strength gains** and fitness targets.

1RM Calculator FAQs

Which 1RM formula is the most reliable?

While the **Epley formula** is the most popular, research suggests formulas like **Brzycki** and **Lander** can be highly accurate, especially for higher rep counts. The result provided by our **1RM calculator** is a strong average **estimate**, but for maximal accuracy, avoid using reps higher than 10.

Do I need to estimate my 1RM for every workout?

No. You only need to calculate your **One-Rep Max** periodically (e.g., every 6-8 weeks) to track your **strength gains** and adjust your **strength goals**. Once your **1RM** is established, you can use percentages of that number to program your workouts for weeks at a time.

Is the 1RM estimate safe for beginners?

Yes, the **1RM calculator** is highly recommended for beginners because it allows you to determine your **max lifting weight** without the risk of attempting a true max lift. Start with a weight you can comfortably lift for 5-8 **repetitions performed** to get a safe, accurate **1RM estimate**.