Use this comprehensive set of formulas to help you determine the quantity of building or landscape material you will need for your project. Most products are sold in cubic feet which is a measure of volume. Adding and subtracting rectangular, circular, and triangular volumetric measurements may assist you in planning efforts with your landscaping project. Volume calculations are necessary when using aggregate (rock), sand, soil, mulch, compost, and concrete. We’re happy to work with all types of clients, commercial contractors, professional landscapers, or do-it-yourselfers, on their landscaping projects. No project is too big or too small.
Landscape supplies tend to vary in depth requirements depending on the product and depending on the application. Keep in mind that some materials may compact more than others when estimating the amount of materials to order. Consult with us for a more detailed estimate of materials.
When you’re planning a project involving landscaping rock, a key question is how much material you will need.
Calculating accurately can save you money and headaches. You don’t want to order too little rock and not have enough to adequately cover your landscape. But if you order too much, you’ve wasted money—and wasted labor spreading it around.
There are two factors to consider when calculating the amount of landscape rock to order for your project:
- The size of the space you’re covering.
- How deep you want the coverage.
To calculate the size, measure the length and the width of your project area. Multiply those two numbers to come up with the square footage of your coverage area. So if your project is 18 feet long by 20 feet wide, your coverage area is 360 square feet.
Next, decide how deep you want your coverage. For most purposes, about 2 inches of material will be adequate. If you’re using materials that are themselves larger than 2 inches, then the depth will probably be the size of the rocks, that is, you’ll just want one layer of 3-8 inch rocks.
The amount of landscaping rock you’ll need depends partly on what size of rock or gravel you want to use. This chart gives you some general estimates of how large an area 1 ton of several different types of material will cover.
The following table is a general guide that may help you estimate the amount of product needed for common landscape projects.
|Product Type||Category||Coverage Area per 1 Ton|
|Flagstone||*2” minus||50 – 80 square feet|
|Flagstone||1 ½”||80 – 100 square feet|
|Flagstone||1 ¼” minus||110 – 140 square feet|
|Flagstone||1” minus||120 – 160 square feet|
|River Cobbles*||Large (6-12”)||30 – 40 square feet|
|River Cobbles *||Small (2-6”)||70 – 80 square feet|
*all-natural stone calculations are approximate due to variations in density and/or thickness
1728 cubic in. = 1 cubic ft.
27 cubic ft. = 1 cubic yard
144 square in. = 1 square ft.
9 square ft. = 1 square yard
1 ton = 2000 lbs.
1 acre = 43,560 sq. ft.
Use these charts to come up with the amount of material you’ll need. You’ll take the square footage you came up with earlier when you measured your project area, then divide it by the coverage area number in the table for the material you’re using.
So if you’re using recommended depth in the chart above, the basic formula you need is this:
L × W = Square footage of coverage area.
Square feet of coverage area ÷ coverage area per 1 ton = tons of rock needed.
Using this formula, you can see that if you’re looking to cover 360 square feet with 1”-3” size rocks, you’re probably going to need 4.5 tons. If you’re using smaller materials, say 3/4”-1”, you may need only 3.6 tons.
|Material||Suggested Depth||Coverage Area per 1 Ton|
|3”-8” rock||3”-8”||60 square feet|
|1”-3” rock||1”-3”||80 square feet|
|3/4”-1” screened gravel||2”||100 square feet|
|5/8”-1/2” screened gravel||2”||120 square feet|
|1/4″-3/8” screened gravel||2”||140 square feet|