What Is .22 inches

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Last updated: April 10, 2026

Quick Answer: .22 inches is a unit of linear measurement equal to 5.588 millimeters or one-hundredth of a foot. It is most commonly associated with .22 caliber firearms and ammunition, where it designates the bullet diameter in inches, making it one of the smallest and most popular civilian rifle cartridges worldwide.

Key Facts

.22 inches equals exactly 5.588 millimeters (5.59mm) or 0.22 centimeters in metric conversion
.22 caliber ammunition was first introduced in 1884 as the .22 Long Rifle, designed for rifles and pistols
.22 Long Rifle remains the most popular ammunition cartridge globally, with over 2 billion rounds manufactured annually
.22 ammunition costs between $0.08–$0.25 per round, making it the most economical rifle cartridge available
.22 inches measurement is used in industrial tolerances, engineering specifications, and precision manufacturing beyond firearms applications

Overview

.22 inches represents a linear measurement of 22 hundredths of an inch, precisely equivalent to 5.588 millimeters in metric units. This specific measurement became historically significant during the late 19th century when firearms manufacturers standardized ammunition calibers based on bullet diameter measurements expressed in decimal inches.

The term is predominantly associated with .22 caliber ammunition, the smallest centerfire rifle cartridge widely used for civilian purposes. While .22 inches technically refers only to the linear distance, in popular usage it encompasses the entire ecosystem of .22 caliber firearms, ammunition types, and related shooting applications that have evolved over more than 140 years of manufacturing and refinement.

How It Works

Understanding .22 inches requires examining its practical applications and relationship to firearms specifications:

Bullet Diameter Standard: In .22 caliber ammunition, the projectile measures exactly .22 inches in diameter, derived from the Imperial measurement system used historically by American gunmakers. This diameter remains consistent across all commercial .22 caliber variants produced worldwide.
Cartridge Variants: Multiple ammunition types share the .22 inch bullet diameter but differ in case length and powder charge. The .22 Long Rifle, introduced in 1887, uses a .22 inch projectile in a longer casing than the earlier .22 Short variant, producing higher velocity and energy suitable for hunting small game.
Manufacturing Precision: Maintaining .22 inch diameter requires strict manufacturing tolerances, typically held to ±0.003 inches during production. Quality ammunition manufacturers use precision machinery to ensure consistent bullet dimensions, critical for accuracy and firearm safety.
Velocity and Energy Characteristics: A standard .22 Long Rifle round fires a 40-grain projectile at approximately 1,200 feet per second, generating roughly 128 foot-pounds of kinetic energy. These ballistic properties make .22 caliber suitable for target shooting, small game hunting, and training applications.
Firearm Compatibility: Rifles and pistols chambered in .22 caliber feature barrel bores measuring .22 inches in diameter, with lands and grooves rifling that stabilize the projectile in flight. This precise bore diameter ensures proper bullet engagement and accuracy performance.

Key Comparisons

Measurement	Metric Equivalent	Common Use
.22 inches	5.588 millimeters	.22 caliber firearms ammunition
.308 inches	7.823 millimeters	.308 Winchester rifle ammunition
.357 inches	9.068 millimeters	.357 Magnum handgun ammunition
1/4 inch	6.35 millimeters	General engineering and construction
6 millimeters	0.236 inches	Metric rifle cartridges

Why It Matters

The .22 inch measurement holds significance across multiple domains beyond casual firearms usage. In industrial manufacturing, precision tolerances specified in decimal inches like .22 inches appear in mechanical engineering, tooling specifications, and component manufacturing where accuracy directly affects product performance and safety.

Shooting Sports Economics: The .22 inch caliber's affordability—approximately one-tenth the cost of centerfire ammunition—makes it essential for competitive shooting programs, military training facilities, and civilian marksmanship instruction where high-volume practice is required.
Wildlife Management: Conservation programs rely on .22 caliber firearms for population control of small predators and invasive species, where the cartridge's ballistic properties provide effective humane harvesting without excessive collateral damage.
Historical Standardization: The .22 inch measurement exemplifies American Imperial engineering standards that influenced global firearms manufacturing throughout the 20th century, establishing conventions still followed in ammunition production today.
Training and Development: Law enforcement and military organizations utilize .22 caliber firearms for basic marksmanship instruction, where minimal recoil and low noise signatures suit training environments while maintaining fundamental shooting mechanics relevant to larger caliber weapons.

Understanding .22 inches extends beyond simple unit conversion; it represents a measurement that shaped sporting traditions, influenced industrial standards, and remains fundamentally relevant to contemporary firearms, manufacturing, and precision engineering applications. This modest measurement unit continues driving economic activity worth billions annually in ammunition production, firearm manufacturing, and associated industries worldwide.