The term “.22 caliber” refers to a family of cartridges, so the exact bullet size depends on the specific ammunition type. A typical .22 caliber bullet measures between 0.223 and 0.2255 inches in diameter, which converts to approximately 5.66 to 5.73 millimeters. Because “.22” is a broad designation rather than a single specification, dimensions vary slightly from one cartridge to another.
22 Bullet Size
| Cartridge | Bullet Diameter (Inches) | Millimeters | Source |
| .22 LR | 0.2255 | 5.73 | SAAMI |
| .22 WMR | 0.224 | 5.69 | SAAMI |
| .22 Hornet | 0.224 | 5.69 | SAAMI |
| .223 Remington | 0.224 | 5.69 | SAAMI |
| .22-250 Remington | 0.224 | 5.69 | SAAMI |
Explanation
The term “.22 caliber” indicates the approximate internal diameter of a firearm barrel, not a single exact bullet dimension. A typical .22 bullet size hovers around 0.224 inches, but the exact number depends on the cartridge. Bullet diameter is the measurement of the projectile itself, while bore diameter measures the distance between the lands (raised ridges) inside the barrel. Bullets are designed to be slightly larger than the bore diameter so they can properly engage the rifling grooves and create a gas seal. Different .22 caliber cartridges have different bullet dimensions because they were developed in different eras for different purposes, utilizing varying case designs, pressures, and barrel twist rates. Consequently, simply stating “.22 caliber” does not identify one specific cartridge.
22 Bullet Size In Inches And Millimeters
Converting inches to millimeters requires multiplying the inch value by 25.4. While the nominal designation is roughly 0.22 inches (5.58 millimeters), the actual standardized bullet diameter for most modern .22 centerfire cartridges is 0.224 inches, which equals 5.69 millimeters. The approximate “.22” label is merely a naming convention used for marketing and categorization. The actual standardized bullet diameters are strictly regulated by organizations like SAAMI and C.I.P. to ensure safety and proper function.
22 LR Bullet Size
The standard bullet diameter for the .22 Long Rifle (.22 LR) cartridge is 0.2255 inches (5.73 millimeters) at its widest point. This measurement is slightly larger than most centerfire .22 caliber bullets because the .22 LR uses a heeled bullet design, where the rear of the bullet is stepped down to fit inside the case while the front matches the outside case diameter. Common bullet weights for the .22 LR range from 30 to 40 grains, with 40 grains being the most widely used standard weight.
22 Bullet Size vs Other Calibers
When comparing the .22 caliber family to other popular bore sizes, the dimensional differences become clear.
| Caliber Designation | Typical Bullet Diameter (Inches) | Millimeters |
| .17 Caliber | 0.172 | 4.37 |
| .20 Caliber | 0.204 | 5.18 |
| .22 Caliber | 0.224 to 0.2255 | 5.69 to 5.73 |
| .24 Caliber | 0.243 | 6.17 |
| .25 Caliber | 0.257 | 6.53 |
| .30 Caliber | 0.308 | 7.82 |
FAQs
What size is a .22 bullet?
A typical .22 bullet measures between 0.223 and 0.2255 inches in diameter, depending on the exact cartridge.
How many millimeters is a .22 bullet?
Most .22 caliber bullets measure between 5.66 and 5.73 millimeters in diameter.
What is the diameter of a .22 LR bullet?
The maximum standard bullet diameter for a .22 LR is 0.2255 inches, which equals 5.73 millimeters.
Is .22 caliber exactly 0.22 inches?
No, .22 caliber is an approximate designation; actual bullet diameters usually range from 0.223 to 0.2255 inches.
Are all .22 caliber bullets the same size?
No, rimfire cartridges like the .22 LR use a 0.2255 inch bullet, while most modern .22 centerfire cartridges use a 0.224 inch bullet.
What is the difference between .22 LR and .22 WMR bullet size?
The .22 LR uses a 0.2255 inch heeled bullet, whereas the .22 WMR uses a slightly narrower 0.224 inch standard bullet.
Is .223 Remington a .22 caliber bullet?
Yes, the .223 Remington is part of the .22 caliber family and uses a bullet with a diameter of 0.224 inches.