One-Rep Max Calculator - 1RPM Calculator

Calculate:

Weight Lifted:

Desired One-Rep Max (1RM):

Number of Reps:

Formula to Use:

1. What is a One-Rep Max Calculator?

Definition: This calculator estimates your one-rep max (1RM) using different formulas (Epley, Brzycki, Lander) based on the weight you lifted and the number of reps, or calculates the weight you should lift for a specific number of reps given a desired 1RM.

Purpose: It helps lifters assess their maximum strength or plan their training by determining appropriate weights for different rep schemes.

2. How Does the Calculator Work?

The calculator uses the following formulas:

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

\( \text{Brzycki: } 1RM = \text{Weight} \times \frac{36}{36 - \text{Reps}} \)

\( \text{Lander: } 1RM = \frac{\text{Weight}}{(1.013 - 0.0267123 \times \text{Reps})} \)

Where:

Weight: The weight lifted (in kg or lb, converted to kg).
Reps: Number of repetitions performed.

Steps:

Select the calculation mode: One-Rep Max (1RM) or Weight for Specific Reps.
Enter the Weight Lifted and Number of Reps (for 1RM) or Desired 1RM and Number of Reps (for weight), choosing the unit (kg or lb).
For "Weight for Reps" mode, select the formula to use (Epley, Brzycki, or Lander).
Validate inputs to ensure they are positive and reps are within a practical range (1-30).
Calculate the result using the appropriate formula(s), converting units as needed.
Display the result(s) to 2 decimal places with the unit dropdown next to it.

3. Importance of One-Rep Max Calculation

Calculating 1RM is crucial for:

Strength Assessment: Estimates your maximum strength without risking injury by attempting a true 1RM lift.
Training Planning: Helps you determine appropriate weights for different rep schemes in your workout program.
Progress Tracking: Allows you to monitor improvements in your lifting performance over time.

4. Using the Calculator

Example 1: Calculate 1RM with 100 kg for 5 reps:

Weight: 100 kg, Reps: 5
Epley: \( 100 \times (1 + \frac{5}{30}) \approx 116.67 \, \text{kg} \)
Brzycki: \( 100 \times \frac{36}{36 - 5} \approx 116.13 \, \text{kg} \)
Lander: \( \frac{100}{(1.013 - 0.0267123 \times 5)} \approx 115.47 \, \text{kg} \)
Result in lb: Epley ≈ 257.21 lb, Brzycki ≈ 255.99 lb, Lander ≈ 254.58 lb

Example 2: Calculate weight for 3 reps with a desired 1RM of 200 lb using Epley formula:

1RM: 200 lb = 90.72 kg, Reps: 3
Weight: \( \frac{90.72}{1 + \frac{3}{30}} \approx 82.47 \, \text{kg} \)
Result in lb: \( 82.47 \times 2.20462 \approx 181.81 \, \text{lb} \)

5. Frequently Asked Questions (FAQ)

Q: What is a one-rep max (1RM)?
A: A one-rep max is the maximum weight you can lift for one repetition with proper form.

Q: Why use multiple formulas?
A: Different formulas (Epley, Brzycki, Lander) provide varying estimates, offering a range to account for individual differences in strength curves.

Q: How accurate are the 1RM estimates?
A: The estimates are generally accurate for most lifters but may vary depending on factors like fatigue, technique, and the number of reps performed.