Power factor is your bullet weight in grains times your muzzle velocity in feet per second, divided by 1000, with the fraction dropped. Enter a few chronograph readings and your division, and it averages them the way a match does and tells you whether you make Major or Minor.
Enter a bullet weight and at least one velocity to see your power factor.
USPSA floors: Major is 165, Minor is 125, and the fraction is dropped, so 164.9 counts as 164 and does not make Major. A load under 125 does not make Minor and is not legal for USPSA competition. Major scores one more point than Minor on C and D hits. Because a match chronograph can read a little lower than your own, a comfortable fps margin over the floor is wise.
How power factor works
Power factor is USPSA's measure of how hard your rounds hit the scoring targets. It is a simple momentum figure: bullet weight in grains times velocity in feet per second, divided by 1000. The fraction is always dropped, so a load that computes to 164.9 is a power factor of 164, not 165.
Major and Minor
USPSA recognizes two scoring tiers. Major is a power factor of 165 or higher; Minor runs from 125 up to 164. A load below 125 does not make Minor and is not legal for competition. Major and Minor score the same on an A hit, but Major loses fewer points on C and D hits, which is why bigger-bore shooters chase it.
Which divisions can score Major
- Major or Minor: Open, Limited, Limited 10, Single Stack, Revolver.
- Minor only: Production, Carry Optics, Limited Optics, Pistol Caliber Carbine.
Leave yourself a margin
The chronograph at a match is the one that counts, and it can read lower than your own. Combined with the dropped fraction, a load that measures right at the floor at home can come up short on match day. Most shooters build in several power factor of headroom so a slightly slow string does not drop them a tier.
See the full guide: What is power factor and how does it work in USPSA →Power factor questions
What is power factor in USPSA?
Power factor is bullet weight in grains multiplied by muzzle velocity in feet per second, divided by 1000, with the fraction dropped. It reflects the momentum of your load and determines whether you score Major or Minor.
What are the Major and Minor power factor floors?
Major is 165 and Minor is 125. A load at 165 or above makes Major, a load from 125 to 164 makes Minor, and anything below 125 is not legal for USPSA competition.
How do you calculate power factor?
Multiply bullet weight in grains by average velocity in feet per second, divide by 1000, and drop the fraction. For example, a 124 grain bullet at 1000 fps is 124,000 divided by 1000, which is a power factor of 124.
Which USPSA divisions can score Major?
Open, Limited, Limited 10, Single Stack, and Revolver can score Major. Production, Carry Optics, Limited Optics, and Pistol Caliber Carbine are scored Minor only regardless of the load.
Why leave a margin over the power factor floor?
A match chronograph can read lower than your own, and the fraction is dropped, so a load that just clears the floor at home may fall under at a match. A comfortable velocity margin protects your Major or Minor call.