Shotgun Gauge Size Chart
Shotgun gauge is a measurement that defines the diameter of the shotgun's bore, or barrel. The lower the gauge of a shotgun, the smaller the diameter of the bore. So a 10 gauge shotgun has a much larger bore than a 28 gauge. However, this naming convention isn’t reflected in the .410 shotgun, which isn’t given a gauge, but is plainly named for its bore’s diameter.
The idea of a “gauge” is analogous to caliber in rifles. Although unlike rifle calibers, you can have different lengths of shotgun shells designed to be fired in the same gauge shotgun. A common length for shotgun shells is 2 ¾ inches, but the longer the shell, the more shot it contains. Longer shells are also more powerful, and not all shotguns can handle every length of shell, even if that length is available in its gauge.
The 12 gauge shotgun is by and far the most popular shotgun gauge. It is great for just about every hunting application where you would use a shotgun. 10 gauge shotguns are reserved for hunting that requires a lot of power, and the 20 gauge is a lower power option that still performs in most hunting scenarios.
SHOT PELLETS PER OUNCE
| Shot Pellet Size | Diameter | Lead Pellet Count per 1 oz |
|---|---|---|
| #9 | .080" (2.03mm) | 585 |
| #8 | .090" (2.29mm) | 410 |
| #7½ | .095" (2.41mm) | 350 |
| #7 | .100" (2.54mm) | 297 |
| #6 | .110" (2.79mm) | 225 |
| #5 | .120" (3.05mm) | 170 |
| #4 | .130" (3.30mm) | 135 |
| #3 | .140" (3.56mm) | 108 |
| #2 | .150" (3.81mm) | 87 |
| #1 | .160" (4.06mm) | 72 |
| B | .170" (4.29mm) | 60 |
| BB | .180" (4.57mm) | 50 |
| BBB | .190" (4.83mm) | 44 |
| #4 Buckshot | .240" (6.10mm) | 21 |
| #3 Buckshot | .250" (6.35mm) | 18 |
| #2 Buckshot | .270" (6.86mm) | 14 |
| #1 Buckshot | .300" (7.62mm) | 11 |
| 0 Buckshot | .320" (8.13mm) | 8 |
| 00 Buckshot | .330" (8.38mm) | 8 |
| 000 Buckshot | .360" (9.14mm) | 6.2 |
Pellets are measured in sizes from #9 to 000 Buckshot. The larger the number, the smaller the size of the individual BBs or shot. The smaller the shot, the more pellets you will have in your shell. So shooters are often striking a balance between a wide spread with lots of shot, and a smaller spread with larger BBs. As the shot size gets bigger, the amount of shot per ounce goes down proportionately as a result.
This shot can be made out of a variety of materials, but it is often measured in “pellets per ounce”. Different materials weigh different amounts, and their pellets per ounce will change as a result. Lead is a popular and cheap option for all non-waterfowl shooting. Although steel, tungsten, bismuth, and proprietary alloy blends are all common to see.
SHELL LENGTHS PER GAUGE
| Gauge |
Shell Lengths
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|---|---|---|---|---|---|---|
| 10 Gauge |
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| 12 Gauge |
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| 16 Gauge |
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| 20 Gauge |
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| 28 Gauge |
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| .410 Bore |
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A 10 gauge shotgun only fires 3 ½ inch magnum shells, and is reserved for situations where you need a lot of power and or range. A 12 gauge shotgun can be used for just about anything, and the flexibility in shell size shows that fact. A 12 gauge shotgun can be built to shoot slugs at deer at 100 yards, or #9 shot at skeet in the backyard, and everything else in between.
16 gauge shotguns are still a little popular, but are not commonly manufactured. This makes their 2 ¾ inch shells expensive, but if you own one, it is great for all kinds of bird hunting. 20 gauge shotguns are the second most popular behind the 12. They are a little smaller, and offer lighter recoil. As a result, you will not find any 3 ½ inch 20 gauge shells.
You will have a hard time finding 28 gauge shotgun shells, but they come in the classic 2 ¾ and 3 inch lengths. They are great for small game, and waterfowl at close range. The .410 is popular because of how small it is, which makes it ideal for children. So your most common shell is going to be 2 ½ inches due to the lighter recoil.
| #9 | #8 | #7.5 | #7 | #6 | #5 | #4 | #3 | #2 | #1 | B | BB | BBB | #00 Buck | #000 Buck | T | #1 Buck | #2 Buck | #3 Buck | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 10 Gauge | X | X | X | X | X | X | X | X | X | ||||||||||
| 12 Gauge | X | X | X | X | X | X | X | X | X | X | X | X | X | X | X | X | |||
| 16 Gauge | X | X | X | X | X | X | X | ||||||||||||
| 20 Gauge | X | X | X | X | X | X | X | X | X | X | X | X | X | X | |||||
| 28 Gauge | X | X | X | X | X | ||||||||||||||
| .410 Bore | X | X | X | X | X |
It is easy to see that some gauges have more shot options than others. 12 gauge is by and far the most popular, and you can get a shot size for every shooting application there is. Other gauges that are not used as often usually offer shot sizes that pairs with the most popular type of shooting that gauge is used for.
For example, the 10 gauge has #2, #4, #5 shot, which are all common for waterfowl and the bigger #2 shot in 10 gauge is a great combo for a goose hunter. Likewise, it is available in the larger BB shots and buck shots, so you can use it for big game as well.
20 gauge is also very popular across all types of shotgun applications, so you can get most shot sizes. Although larger buck shot is a little too big for a 20 gauge barrel, so you are limited to #1 through #4 buckshot. 16 gauge has shot sizes closely associated with all types of bird hunting, and the 28 gauge caters towards small bird hunting like doves.
GAUGE BORE DIAMETERS
| Gauge | Bore Diameter (in) | Bore Diameter (mm) |
|---|---|---|
| 10 Gauge | .775" | 19.69mm |
| 12 Gauge | .725" | 18.42mm |
| 16 Gauge | .665" | 16.89mm |
| 20 Gauge | .615" | 15.62mm |
| 28 Gauge | .545" | 13.84mm |
| .410 Bore | .410" | 10.41 mm |
When someone is describing the “gauge” of a shotgun, that refers to how large the barrel is. More specifically, it refers to how big around the barrel is, aka, the diameter of the bore. To most, there doesn’t seem to be a whole lot of logic behind the naming of the gauges. Just like all other American made measurements, we made it overly complicated.
A 12 gauge shotgun has a 0.725 inch bore diameter, but the “12” is calculated in a different way. The 12 refers to how many lead balls of size equal to the bore diameter (so 0.725 inches around) that it would take to weigh one pound. With a little rounding, it takes about 12 0.725 inch lead balls to weigh one pound. The same can be said for all of the other shotgun gauges.
While that may sound complicated, saying you shoot a 12 gauge is a whole lot easier than saying you shoot a 0.725 inch scattergun. We have used this convention for a long time, and it isn’t going anywhere anytime soon.