Gravel sizes can vary a little bit by location and distributor, but in most cases the crushed rock composite is available in more or less uniform sizes ranging anywhere from fine powder to pea-sized, coin-sized, or even golf ball-sized pieces. Most retailers and outlets used a numerical system to assign a size. The smallest is usually #10, #57 sits somewhere in the middle, and the biggest is usually #1. The number system is more often related to what the gravel is intended to be used for rather than its measurements. People who are in the market for gravel usually need to spend a bit of time thinking about the specifics of their project, then researching the size that would be most appropriate for that use.
Basics of Sizing
The gravel sizing system can be confusing on first glance, and isn’t always exactly consistent from place to place. Most manufacturers and distributors around the world use a numeric coding system that corresponds to larger guidelines about project specifications, and though there’s usually general industry consistency, it isn’t always exact. People who have stringent sizing specifications are usually wise to talk directly with a distributor or manufacturer to get more information on what is available and what the specifications are.
The smallest of all gravel sizes is usually size #10, which is also commonly known as screenings gravel. This gravel is typically around 1/8th of an inch (0.32 centimeters) in diameter, making it similar in appearance to coarse sand. Often, screenings gravel is used as the base for bricks, paving stones, and other similar items. In some cases, it can also be packed into the crevices created when other, larger stones are stacked, therefore aiding in the prevention of slippage. Size #10 gravel can be made from a variety of larger stones, but is most often made from slag or limestone.
Size #67 is usually about the same size as #10, but often has a slightly different purpose. It’s commonly used as fill in roadways and concrete slabbing. Gravel labeled size #5 is similarly little more than a fine powder; it’s often used in paving to help seal everything together and to fill in crevices between larger pieces.
Size #57 is another of the more popular gravel sizes. This particular size of gravel ranges in diameter from 3/4th of an inch (1.9 centimeters) to 1 inch (2.54 centimeters) in diameter. This gravel is often used for paving walk or driveways, at it can be walked and driven on with relative ease. Though size #57 serves many purposes, it usually is avoided for use in areas that are prone to become muddy.
There are a number of other mid-range sizes available in many places, too, most of which are designed with specific projects or uses in mind. Size #3, for instance, is usually 1.5 to 2 inches (about 3.8 to 5 cm) in diameter, and is often best for residential draining projects; #8, which is usually 3/8 to 1/2 an inch (1 to 1.2 cm) across, is frequently used in asphalt and concrete mixtures. Gravel labeled #411 is usually a mixture of #57 and stone dust, and is particularly useful for patching potholes and sealing things like retaining walls.
Gravel known as size #1 is relatively large. Typically, this gravel ranges in diameter from 2.5 inches (6.35 centimeters) to 4 inches (10.16 centimeters). It can be difficult to work with, as it generally cannot be shoveled and instead must be moved individually, stone by stone. As with other types of very large gravel, size #1 is primarily used as decoration, and can be found in yards, gardens, or even parks. This type of stone is typically available in washed river gravel, slag, or limestone, though other materials may be available in some cases.
Making the Choice
In most cases, people should choose their gravel based on the needs of their project rather than the numerical code on the label. Though sizing is more or less consistent from place to place, the only way to be sure about a bag’s contents is to read the description carefully or to talk with a sales professional about exactly what is inside. Contractors who are really familiar with regional sizing specifications and differences between brands and materials are often in the best position to give seasoned advice.