How Much Gravel Do You Need?
Gravel quantity is based on two basic measurements: the surface area being covered and the depth of the gravel layer. Multiplying the area by the depth produces the volume of material required.
For rectangular areas such as driveways, walkways, and parking areas, measuring the length and width is usually straightforward. Circular areas can be measured using the radius or diameter. If you already know the total area, you can use that measurement directly.
Why Gravel Is Usually Sold by Volume or Weight
Gravel may be sold by the cubic yard, cubic meter, ton, or other unit depending on the supplier and quantity being purchased. Volume tells you how much physical space the material needs to fill, while weight depends on the density of the particular material.
Two types of gravel occupying the same volume don't necessarily weigh the same. Particle size, stone composition, moisture, and how loosely the material is loaded can all affect its weight.
Allowing for Uneven Ground, Settling, and Compaction
A calculated gravel quantity assumes that the entered area and depth accurately represent the finished project. Real surfaces are rarely perfectly level, however, and gravel can settle or compact after it is placed.
For that reason, some projects may require more material than the basic geometric volume. If you decide to purchase extra material, the calculator's allowance option can add your chosen percentage to the calculated quantity.
Bulk Gravel vs. Bagged Gravel
Small projects are often practical to complete with bagged gravel, while larger projects may be more economical or convenient with bulk material from a landscape or aggregate supplier.
When using bags, compare the amount contained in each package with the total volume or weight required. Since you normally can't purchase a fraction of a bag, the number of packages must be rounded up to the next whole bag.
For bulk purchases, suppliers may quote material by volume or weight. Using the same unit as the supplier makes it easier to compare the calculated requirement with the amount you're actually ordering.
Getting a Better Gravel Estimate
Accurate measurements make the biggest difference. Measure the actual area to be covered, subtract portions that won't receive gravel, and use the intended finished depth.
For weight estimates, a density supplied by the gravel seller will generally be more specific to the material you're buying than a general gravel estimate. Supplier information is also useful when determining available quantities, delivery loads, and how the material is sold.