Pea gravel consists of pea-sized rocks frequently used in landscape projects from garden walkways to dog kennels. Homeowners with large projects can buy loose pea gravel in bulk, but most people buy it in bags sold by weight. After calculating the area of coverage, you need to do a little more math to determine the number of bags for your project.
How Many Pea Bags?
A dozen bags of pea gravel can be a more realistic option than buying in bulk, because you can determine exactly how many bags are needed. Unlike mulch bags, which almost always identify the area that they cover, pea gravel bags tend to provide weight, only leaving homeowners recalculating while in the store. If you need to cover 40 square feet, how many 50-pound bags of pea gravel do you need to buy?
Consult Your Tape Measure
To calculate the square footage, measure the length and width of the area you want to cover and multiply the results together. For example, a 4-foot-wide, 10-foot-long strip between a shed and a fence measures 40 square feet. To determine the cubic footage of the area, multiply the square footage, 40 square feet in this case, by the desired depth. A depth of 3 inches provides a good layer of pea gravel for controlling weeds in a hard-to-manage location, especially if laid over weed-barrier fabric. But to use this depth with your square footage calculation, you need to convert it to feet. Divide 3 by 12, and you have a depth of 0.25 foot. The example cubic-foot calculation is then 40 square feet times 0.25 foot, which equals 10 cubic feet.
Versatile Pea Gravel
Pea gravel indicates size, rather than rock type. It's typically sold in 3/8- and 5/8-inch sizes and in a mixture of brown, gray and white earth tones. It provides a textural contrast, as well as a comfortable surface for walking, and is easily cleaned when placed in dog kennels. The small pebble size locks flagstones in position, filling small cracks and irregular shapes. The size of pea gravel you choose has little effect on the quantity you need when buying by weight.
50 Pounds of Peas
A 50-pound bag of pea gravel is equivalent to 0.5 cubic foot, so two 50-pound bags cover 1 cubic foot. Knowing that a 50-pound bag of pea gravel averages 0.5 cubic foot makes the calculation easy -- and one most smartphone calculators can complete. If you determined that you need to cover 10 cubic feet, simply multiply the project size by 100 pounds, the weight of 1 cubic foot, or two bags, of pea gravel, which gives you 1000. Divide this by the 50 pounds that each bag weighs to determine the actual number of bags to buy. In this case, the 4-foot-wide, 10-foot-long, 3-inch-deep strip requires 20 bags of pea gravel when each bag weighs 50 pounds.
Occasionally Misleading Information
Stores occasionally publish square-foot coverage for 50-pound bags by stating that a 0.5-cubic-foot bag of pea gravel covers an approximate square footage, but they fail to provide the depth. That number needs to be worked into the calculation to ensure you purchase enough pea gravel for your project.
Carol Knepp has been writing since 1983, with work published in the "Denver Post," "Green Thumb News," "Westlake Picayune" and on multiple websites. Knepp is a professional gardener, forester, and educator with experience at two botanic gardens, a wilderness preserve nature center and has two degrees, Forestry and Elementary/Pre-K Education.