This calculator helps you estimate the equivalent barbell back squat weight based on your performance on the 45-degree leg press machine, considering reps completed and target intensity.
Leg Press to Squat Calculator
Estimated Equivalent Squat Weight:
This is the estimated weight (in Lbs) you should use for your target squat reps.
Leg Press to Squat Calculator Formula
The calculation estimates a 1 Rep Max (1RM) for the Leg Press, applies a conservative conversion factor (0.65 for a 45-degree sled) to estimate the Squat 1RM, and then uses the estimated Squat 1RM to solve for the weight at your target reps.
Source for 1RM Epley Formula variant: ExRx.net | Source for Leg Press Conversion Factor: NSCA Research
Variables Explained
- Leg Press Weight Used (L): The total weight (plates + sled) you used for your set. Must be a positive number.
- Reps Completed (R): The number of successful repetitions performed with the Leg Press Weight. Used to estimate your 1RM.
- Target Squat Reps ($R_{target}$): The number of repetitions you plan to perform with the estimated Squat Weight.
- Equivalent Squat Weight (S): The estimated weight you should use for your target squat reps.
Related Calculators
What is Leg Press to Squat Equivalence?
The Leg Press to Squat equivalence is a comparison method used to estimate how much weight you can move in a barbell back squat, based on your strength demonstrated in a leg press exercise. Because the leg press is a fixed, guided movement that eliminates stabilization requirements and partially mitigates gravity (especially on a 45-degree sled), the weight lifted is typically much higher than in a free-weight squat.
This calculator provides a practical way for lifters to transition between machine-based training and compound, free-weight movements. The conversion factor used aims to account for the biomechanical differences, muscle activation patterns, and the need for core stability inherent in the squat that are absent in the leg press. It should be used as an initial estimation, not a perfect prediction.
How to Calculate Squat Weight from Leg Press (Example)
- Identify Leg Press Performance: You performed a Leg Press with 400 Lbs for 10 Reps. (L=400, R=10).
- Set Target Squat Reps: You want to know the estimated weight for 5 Reps. ($R_{target}$=5).
- Estimate Leg Press 1RM ($1RM_L$): $400 \times (1 + (10 \times 0.0333)) = 533.2$ Lbs.
- Estimate Squat 1RM ($1RM_S$): $533.2 \times 0.65 = 346.58$ Lbs. (Applying the conversion factor).
- Calculate Target Squat Weight (S): $\frac{346.58}{1 + (5 \times 0.0333)} \approx 298.1$ Lbs.
- Final Result: The estimated equivalent squat weight for 5 reps is approximately 298 Lbs.
Frequently Asked Questions (FAQ)
Why is my Leg Press weight so much higher than my Squat weight? The leg press is a fixed-plane movement that removes the balance and stabilization requirements crucial in a free-weight squat. Additionally, on a 45-degree sled, you are only pushing against the weight’s vector, not the entire gravity-affected load, making the exercise significantly easier.
Can this calculator be used for Hack Squat? No, this calculator is specifically calibrated for the standard 45-degree sled leg press. The Hack Squat has different biomechanics and activation patterns, meaning the conversion factor (0.65) would be inaccurate.
Is the calculation accurate for all lifters? No. The formula uses common estimations (like the Epley formula for 1RM and an average conversion factor). Individual limb length, core strength, experience, and specific machine geometry will cause variations. Use this as a starting point.
What is the “Conversion Factor” used in the formula? The standard conversion factor for a 45-degree leg press sled is generally accepted to be around 0.6 to 0.7 when estimating squat 1RM. This calculator uses 0.65 for a conservative, balanced estimate.