The Taylor Knock-out Factor calculator approximates the stopping power of a cartridge based on its bullet mass, velocity, and diameter.
INSTRUCTIONS: Choose units and enter the following:
- (M) Mass of Bullet
- (V) Velocity of Bullet
- (D) Diameter of Bullet
Taylor Knock-out Factor (TKOF): The returns the Taylor Knock-out Factor as a real number. It also returns the kinetic energy (KE) of the bullet in Foot-pounds. However, this can be automatically converted to compatible units (e.g., Joules) via the pull-down menu.
The Math / Science
The formula for the Taylor Knock-out Factor is:
`TKOF = (M*V*D)/7000`
where:
- TKOF = Taylor Knock-out Factor
- M = Mass of the bullet converted to grains.
- V = Velocity of the bullet converted to feet per second.
- D = Diameter of the bullet converted to inches.
The Taylor Knock-out factor was developed by big game hunter John Taylor in the mid 20th century as a way for him to compare the power not only of different cartridges but the same cartridge between different rifles, where velocity can vary with barrel length and other factors. It is calculated by multiplying the mass, velocity, and diameter together and dividing by 7000, the number of grains in a pound. The result is a unitless value known as the Taylor Knock-out Factor which normally varies from 0-150 with typical cartridges. Anything above 30 is a very powerful cartridge, some examples based on typical loads include the .375 H&H Magnum with a TKOF of ~35, the .416 Rigby with a TKOF of ~57, and the .600 Nitro Express with a TKOF of ~147. Most common pistol cartridges come in from about 1-15 with .22 long rifle being about TKOF of ~1.3, 9mm at around TKOF ~7 and .45 ACP at TKOF ~12.
The formula for Kinetic Energy is:
where:
- KE is the kinetic energy
- m is the mass of the bullet
- v is the bullet's velocity
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