Bullet Sizes – Complete Guide and Caliber Charts

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In this guide, we review common handgun and rifle calibers with charts of 38 different bullet sizes.

The terminology for different calibers and sizes can be confusing. We aim to simplify this language so that you can easily understand it.

Bullet Sizes
Jason showing all of the different bullet sizes and calibers
Some Rifle and Handgun Cartridges with different Bullet Sizes and Calibers

We have over 50 years of combined experience with various firearm calibers, including military, ammunition reloading, and competition experience. Our data is based on industry-standard guides.

Keep reading to find the bullet sizes of different calibers as well as the power of each one.

Bullet Sizes and Calibers

Bullet sizes and calibers can be confusing due to a mix of metric and English standards, as well as special names assigned to some sizes and calibers like Magnum or someone’s name. However, it’s important to understand some basics about ammunition before delving into the details of each.

The Components of Ammunition

Modern firearms today use cartridges. While it is common to call these cartridges “bullets,” the bullet is actually just the projectile that is part of the cartridge.

A cartridge includes four components:

  • Primer
  • Case
  • Gunpowder or Propellant
  • Bullet
Jason showing the components of Ammo
From the left, the Primer, Case, Gun Powder, and Bullet

A firearm has a hammer or striker that makes contact with the primer. The primer ignites inside the case, which, in turn, ignites the propellant. The pressure from the expanding gases released from the burning propellant pushes the bullet speeding down the barrel.

There are two basic types of cartridges called Rimfire and Centerfire.

Jason showing a Centerfire and Rimfire case
A .22LR Rimfire case on the left, a 9mm Centerfire case on the right
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Rimfire cartridges are the smaller of the two, and they are characterized by not having a visible separate primer in the center of the case. The primer is embedded in the rim of the case. These cartridges are fired by the firearm’s hammer striking the case’s rim. 22 long rifle ammo is a common example of Rimfire cartridges.

Centerfire cartridges all have the primer in the center of the case. In the picture above and below, you can see the smaller circle in the center of the case. The most common ammunition today that is not a .22 long rifle is centerfire.

Jason showing a fired Rimfire and Centerfire cartridge
A fired Rimfire case on the left, a fired centerfire on the right

The other main difference between Rimfire and Centerfire is Rimfire cartridges can not be reloaded. After centerfire cartridges are fired, the primer can be removed and a new one pressed into place.

We should also note that shotgun ammo differs slightly from Rimfire and Centerfire cartridges. Instead of a bullet, they have small balls called “shot.” Overall, they function very similarly.

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What does the Caliber of a Firearm Mean?

In general, bullet sizes and calibers are named by the approximate diameter of the firearm barrel. For example, 9mm is a metric caliber that measures about 9mm in diameter. For English calibers, they are measured in inches. A “45 caliber” has a barrel diameter of 0.45 inches.

However, there is more to it than just the bullet’s diameter. Cartridges have different shapes and lengths. Modern handgun cartridges do not vary as much, but rifle cartridges can have many different names and shapes.

Larger and longer cartridges provide more room for gunpowder, making the bullet travel faster and farther and have more power overall.

The different lengths of cartridges are handled in two different ways. For Metric cartridges, the length of the cartridges is noted with a second number. 5.56x45mm is a common rifle cartridge with a 5.56mm diameter bullet and a case length (without the bullet) of 45mm.

English cartridges, or those measured in inches, vary with how the case is specified. Usually, they will have a caliber number along with a name or word. A .38 Special cartridge has a 0.358” diameter bullet and a 1.155-inch long case. A .357 Magnum cartridge also has a 0.358” bullet, but the case is 1.290 inches long.

Some will have a second number and a name, like the 30-30 Winchester rifle cartridge.

Jason showing the markings on the barrel of his rifles
The markings on the barrel of two of my rifles show the caliber they will fire

Regardless of your firearm, it is important to match up the named caliber on your firearm with the cartridge.

But, there are some special cases.

In our English example above, a .38 special cartridge will fire just fine in a .357 Magnum handgun. However, a .357 Magnum cartridge is not safe to fire in a handgun that is marked .38 special. This is because the .38 special cartridge has lower overall power, and a handgun designed for the .38 special cartridge may not be able to handle the power of the .357 cartridge (and it may not fit in the gun anyway.)

Jason showing a 357 Magnum and a 38 Special cartridge
A 357 Magnum on the left and a 38 Special on the right

In the end, if you are not sure, just match up your ammo to the markings on your firearm.

See our full guide on Bullet Speeds to learn more about the speeds of different calibers. See our guide on the differences between 9mm vs 9mm Luger to learn how cartridges are named and the things to watch out for.

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What is the Grain of a Bullet?

Most calibers today are available in cartridges with different bullet grains. The grain of a bullet is simply the weight of the bullet.

Grains are a very old unit of weight measurement. One grain is very small, around 0.002 ounces. Or, 1 ounce is about 437.5 grains.

Since grains are a small unit of measurement, it is an easy way to weigh bullets since they are light in weight, and so we don’t have to use a bunch of decimal numbers. It would be harder to call a 135-grain bullet a 0.3086-ounce bullet, for example.

In general, with the same amount of gunpowder, a heavier bullet will travel slower when compared to a lighter bullet of the same caliber. This is because it takes more force to move a heavier weight.

Jason measuring the grain of a bullet
This is a 124-grain bullet that I weighed on my bullet scale

I have found that a heavier bullet will have less felt recoil, but the firearm’s action will travel slower. I can feel this in my competition handguns when I reload my ammunition with different-grain bullets. I could not tell the difference for many years until I fired thousands of rounds in practice. For most people, the grain of the bullet you use is not a huge concern.

There is a misconception that a heavier bullet is more powerful. This would be true if two bullets were traveling at the same speed. The heavier one would be more powerful.

However, firearms are designed to only handle a certain amount of chamber pressure. Keeping pressure equal, the heavier bullet will travel slower since it takes less force to move the lighter bullet.

If we compare the Federal HST 124 gr round to the Federal HST 147 gr round, we find that the 124 gr bullet travels at 1150 fps while the 147 gr bullet travels at 1000 fps. The resulting muzzle energy is 364 ft-lb for the 124 gr and 326 ft-lb for the 147 gr.

As you can see, since heavier bullets travel slower out of the same gun, they will, in fact, induce less force than a lighter one.

Types of Bullets

Different types of bullets are used for different purposes. These include:

  • FMJ – Full Metal Jacket
  • HP or JHP – Hollow Points or Jacketed Hollow Points
  • SP – Soft Point
  • Plated Bullets
  • Armor Piercing Bullets

For more on each type of bullet and how it affects the cost, see our full guide on the cost of ammo.

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Common Handgun Bullet Sizes and Calibers

Now that we understand all of the components of an ammunition cartridge, here is some data on the common handgun bullet sizes and calibers.

Jason showing various fired handgun calibers
Fired handgun cases, notice the different diameters and markings on each

What Caliber is .22LR?

The .22 LR has a 0.223” diameter bullet. Commonly referred to as the “twenty-two,” the .22 long rifle is one of the most common handgun and rifle calibers today. It is popular for small game hunting and practice since it has minimal recoil, and the cost is lower than any other caliber. There is also a “.22 short” cartridge available with a shorter case; however, it is not as popular today. When most people say “twenty-two,” they are referring to the .22LR.

What Caliber is .380 ACP?

The .380 ACP has a bullet with a 0.355” diameter. It is a small, low-recoil caliber popular for people who carry concealed and are recoil-sensitive. It is mainly used in semi-automatic handguns.

What Caliber is .38 Special?

The .38 Special has a bullet with a 0.355” diameter. It used to be the standard law enforcement caliber for revolvers years ago before semi-automatic handguns became reliable. It has the same bullet as the .380 ACP but has a longer case. It is only used in revolvers.

What Caliber is .357 Magnum?

The .357 Magnum has a 0.355” diameter bullet. It is the big brother to the .38 special and has an even longer case. It is only used in revolvers.

What Caliber is 9mm?

The 9mm bullet is 9mm in diameter, or about 0.355 inches. The 9mm is the most common handgun round available today. It is essentially the same caliber as the .380 ACP, but the case length is between the .380 ACP and the .38 special. It is also sometimes called the 9mm Luger. It is the most popular cartridge for law enforcement and concealed carry.

Jason's 9mm Bullets, 5 purchased and one he reloaded. Each has a different bullet type and weight
Various 9mm cartridges

See our review of the new PMC SFX 9mm ammo to see how concealed carry ammo performs in ballistics gel.

What Caliber is 40 Smith & Wesson?

The 40 Smith & Wesson has a bullet diameter of 0.401”. Years ago, this was the most popular cartridge for law enforcement until advancements in bullet technology made the 9mm round the preferred caliber. It has a slightly longer case compared to the 9mm.

What Caliber is 45 Automatic (45 ACP)?

The 45 ACP has a bullet diameter of 0.45”. The “Forty-five” has existed since the early 1900s. John Browning designed the round for the US military and shortly followed up with the M1911 pistol, which is still popular today. The case is slightly longer than the 40 Smith & Wesson.

Table of Common Handgun Calibers and Bullet Sizes

CaliberBullet Dia (in)Case Length (in)Case Dia (in)Muzzle Energy (ft-lbs)
22 LR0.2230.6130.225128
380 ACP0.3550.6800.374211
38 Super0.3560.9000.384338
38 Special0.3581.1550.379200
357 Magnum0.3581.2900.379486
357 Sig0.3550.8650.424399
9mm Lugar0.3550.7540.391309
40 S&W0.40050.8500.424367
44 Magnum0.4321.2850.457781
45 ACP0.4520.8980.476359
45 Colt0.4561.2850.480431
500 S&W0.5001.6250.5302887

*Note that muzzle energy can vary depending on the mass of the bullet and the powder type and load. These are approximate averages.

Common Rifle Bullet Sizes and Calibers

These are the most common rifle bullet sizes and calibers, with a full chart to follow.

Jason showing different Rifle Calibers
Various Rifle Calibers from .22LR to 450 Bushmaster

What Caliber is .223 Remington?

The 223 Remington has a bullet diameter of 0.224”. It was introduced by Remington in 1964, soon after the military adopted the 5.56 NATO. It is the same as the 5.56 NATO caliber; however, it fires at slightly lower pressures. The main difference is a 5.56 NATO cartridge is loaded with more gunpowder, creating higher pressures and bullet speeds. Because of this, it may not be safe to fire a 5.56 NATO round in a rifle marked for .223 Remington.

What Caliber is 5.56? Also known as the 5.56 NATO

The 5.56x45mm has a bullet diameter of 0.224”.  5.56 ammo is also commonly called 5.56 NATO since it is a standard round of NATO countries. It is also the most popular round for the AR15 rifle. Common military standard cartridges include the M193 and the M855.

What Caliber is 6.5 Creedmoor?

6.4 Creedmoor has a bullet diameter of 6.72mm or 0.264 inches. This rifle caliber was developed in 2007 as a new long-range cartridge. It is popular for long-range target shooting and deer hunting.

What Caliber is 270 Winchester?

The 270 Winchester has a bullet diameter of 0.277 inches. It is a popular big game hunting caliber developed by Winchester in 1925.

What Caliber is 300 AAC Blackout?

The “300 Blackout” has a bullet diameter of 0.308 inches. It is a cartridge that has a bullet similar to the popular .308 Winchester but uses a cartridge similar to the smaller 5.56 NATO. The result is a larger bullet that can be used in subsonic applications for the common AR-15 rifle. It uses the same magazines and bolt carrier as the 5.56 NATO and only requires a different barrel.

What Caliber is 30-30 Winchester?

The “Thirty Thirty” has a bullet diameter of 0.308 inches. It was introduced in the classic lever action rifle by Winchester in 1895. Hunters have probably used it to harvest more deer in North America than any other caliber. I have my grandfather’s 30-30 and will hand it down to my grandson.

What Caliber is 308 Winchester? Also known as 7.62 x 51mm or 7.62 NATO

The “Three-Oh-Eight” has a bullet diameter of 0.308 inches. It is perhaps the most popular and versatile modern rifle caliber. It was adopted by the US military in the late 1950s. It works great for hunting as well as long-range target shooting. It is the most common caliber in the AR-10, the AR-15 Big Brother.

The main difference between the 308 and the 30-30 is the 308 is loaded with more gunpowder and develops much higher pressures and bullet speeds. In some cases, it is 50% faster.

7.62x51mm (or 7.62 NATO) cartridges can be fired in a .308 rifle. However, .308 cartridges may not function correctly in a rifle marked specifically for 7.62 NATO due to slight differences in the cartridge thickness.

Table of Common Rifle Calibers and Bullet Sizes

CaliberBullet Dia (in)Case Length (in)Case Dia (in)Muzzle Energy (ft-lbs)
17 Hornet0.1721.3500.298586
223 Rem0.2241.7600.3761263
6mm PPC0.2431.5150.4431450
243 Win0.2431.0450.4701983
6.5 Grendel0.2641.5200.4411545
6.5 Creedmoor0.2641.9200.4702105
6.8 SPC0.2771.68640.42071715
270 Win0.2772.540.4412706
7mm Rem Mag0.2842.500.4913100
7mm Rem
Ultra Mag
300 AAC
30-30 Win0.3082.0390.4211686
308 Win0.3082.0150.4542706
300 Win Mag0.3082.620.5133598
338 Rem
Ultra Mag
338 Lapua0.3382.7240.5874669
375 Rem
Ultra Mag
450 Bushmaster0.4501.7000.5002448
458 SOCOM0.4581.5750.5382158
45-70 GOVT0.4572.1050.5042470
50 Beowulf0.5001.6500.5402405

*Note that muzzle energy can vary depending on the mass of the bullet and the powder type and load. These are approximate averages.

What’s Next?

Be sure to check out our other firearm-related guides in our Self-Defense Guides and Gear Reviews section. We also have a full concealed carry guide with everything you need to know, including mindset techniques.

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Jason has an engineering and problem solving background. He is an avid outdoorsman, survivalist, and competitive shooter. He enjoys researching the best and most practical solutions for the problem at hand, studying stoicism, and finding innovative ways to be prepared.