Uspsa Power Factor Calculator

USPSA Power Factor Calculator

Calculated Power Factor

function calculatePF() { var weight = parseFloat(document.getElementById('bulletWeight').value); var velocity = parseFloat(document.getElementById('velocity').value); var resultArea = document.getElementById('resultArea'); var pfDisplay = document.getElementById('pfDisplay'); var statusDisplay = document.getElementById('statusDisplay'); if (isNaN(weight) || isNaN(velocity) || weight <= 0 || velocity = 165) { statusDisplay.innerHTML = 'MAJOR POWER FACTOR'; statusDisplay.style.backgroundColor = '#d4edda'; statusDisplay.style.color = '#155724'; } else if (pf >= 125) { statusDisplay.innerHTML = 'MINOR POWER FACTOR'; statusDisplay.style.backgroundColor = '#fff3cd'; statusDisplay.style.color = '#856404'; } else { statusDisplay.innerHTML = 'SUB-MINOR (FAIL)'; statusDisplay.style.backgroundColor = '#f8d7da'; statusDisplay.style.color = '#721c24'; } }

Understanding USPSA Power Factor

In the world of the United States Practical Shooting Association (USPSA), Power Factor (PF) is a crucial metric used to categorize the momentum of a cartridge. It ensures that the competitive playing field remains fair by balancing the speed and accuracy of lower-recoiling rounds against the increased difficulty of managing higher-recoiling, more powerful ammunition.

The Official Formula

The calculation for USPSA Power Factor is straightforward physics. It measures the momentum of the projectile using the following formula:

Power Factor = (Bullet Weight in Grains × Muzzle Velocity in Feet Per Second) / 1000

Scoring Tiers: Major vs. Minor

USPSA recognizes two primary power tiers. Your designation determines how many points you receive for hits outside of the "A" zone (Alpha) on a target.

• Major (165+): Higher scoring for B, C, and D zones. This rewards shooters for managing the increased recoil of powerful rounds (typically .40 S&W, .45 ACP, or high-pressure 9mm in Open Division).
• Minor (125 – 164.9): Standard scoring. Most shooters in Production, Carry Optics, and Limited-10 use Minor power factor to benefit from faster follow-up shots and higher magazine capacities.
• Sub-Minor (< 125): Ammunition that falls below a 125 power factor is generally not allowed for score and results in shooting "for no score" or disqualification from the match ranking depending on specific division rules.

Why Velocity Matters

Muzzle velocity can change based on several factors, including barrel length, ambient temperature, and powder charge. Professional competitors often "chrono" their loads to ensure they have a safety margin. For example, if you aim for a 125 Minor PF, a cold morning might drop your velocity, causing you to fail the chronograph stage. Most shooters aim for a "cushion," such as a 130 PF for Minor or 170 PF for Major.

Example Calculations

Bullet Weight	Velocity	Power Factor	Category
115 gr	1,100 fps	126.5	Minor
124 gr	1,050 fps	130.2	Minor
180 gr	920 fps	165.6	Major
230 gr	750 fps	172.5	Major

Important Considerations for Competitors

When using this USPSA power factor calculator, remember that your official match PF will be determined by the match's official chronograph using your firearm. Always test your loads across your own chronograph in various weather conditions to ensure your competition ammo is legal and consistent.