- How to Calculate Cubic Yards of Concrete & Number of Bags Needed
- How Many Pounds of Topsoil in a Yard?
- How to Calculate Dirt Yards
- How to Calculate the Cement for Concrete Garage Floor
- How to Measure Concrete for 8' Sonotubes
- How Much Is a Yard of Topsoil?
- How to Measure for Yard Mulch
- How to Calculate Weight Per Cubic Yard of Gravel
- How to Convert 1 Yard of Topsoil

## How to Calculate Cubic Yards of Concrete & Number of Bags Needed

The amount of concrete you need for a paving project depends on the total volume of the poured concrete. Since concrete volume is typically measured in cubic yards, this means computing the cubic yardage.

Once you know the number of cubic yards of concrete, you can easily determine the number of bags with a simple conversion formula. Just follow the easy math steps below.

First, determine the square footage of the area that you will pave. For rectangles, this means width times length. For circles, use the formula πr².

For example, if it is a 15' by 18' foot rectangle, the area is 15x18 = 270 square feet. If it is a circle with a radius of 8 feet, the square footage is π8² = 201.

Determine the depth of the paved area, also measured in feet. (It may be helpful to know that 4 inches = 0.333 feet, 6 inches = 0.5 feet, and 8 inches = 0.667 feet.) Then, multiply the square footage by the depth, and this gives you the cubic footage.

For example, if you are paving a 15' by 18' rectangle with 6 inches of concrete, then the number of cubic feet is 270 times 0.5, which equals 135 cubic feet.

Now convert the cubic feet to cubic yards by dividing by 27. This is because there are 27 cubic feet in every cubic yard.

Using the example above, we have 135 cubic feet of concrete to pour, and thus the number of cubic yards is 135/27 = 5.

Use the number of cubic yards and this conversion table to calculate the number of bags of concrete you'll need.

1 cubic yard = 90 forty-pound bags

1 cubic yard = 60 sixty-pound bags 1 cubic yard = 45 eighty-pound bags

Simply multiply the cubic yardage by either 90, 60, or 45. For example, to pave 5 cubic yards, a person would need either

450 forty-pound bags, or 300 sixty-pound bags, or 225 eighty-pound bags.

## How Many Pounds of Topsoil in a Yard?

Topsoil and other loose items such as gravel, sand and rock are measured in cubic yards. A cubic yard of topsoil can weigh different amounts depending on the moisture content. Assuming the topsoil is dry, an average a cubic yard will weigh 2,250 lb.

## How to Calculate Dirt Yards

Before you can calculate the cubic yards of dirt needed for a gardening project, you must first determine the area of the garden bed you wish to fill.

Using your tape measure, measure the width and the length of your garden bed. For example, your flower bed may be four feet wide by 10 feet long.

Now determine how deep your gardening dirt will be. For example, if you are building a new raised garden bed, you may plan on making the bed eight inches deep.

Multiply both your width and length by 12 to convert the numbers from feet to inches. For our example 4 x 12 = 48 inches wide, and 10 x 12 = 120 inches long. Now multiply the width, length and depth to find the cubic inches. 48 x 120 x 8 = 46,080 cubic inches.

To determine the cubic yards of dirt necessary to fill a bed of 46,080 cubic inches, divide by 46,656. This is the number of cubic inches in a cubic yard. 46,080 cubic inches divided by 46,656 equals 0.987 cubic yards. You can round this up to one cubic yard of gardening dirt.

## How to Calculate the Cement for Concrete Garage Floor

Use your calculator to multiply the length of the concrete slab in feet by the width of the concrete slab in feet. Multiply the result by the thickness of the slab in feet. The result is the number of cubic feet in the concrete slab. If your garage is 10 ft. by 27 ft. and the slab is 1 ft. deep, then, 27 x 10 x 1 = 270 cubic feet of concrete.

Divide the number of cubic feet in the concrete slab by 27. There are 27 cubic feet in one cubic yard. If you need 270 cubic feet of concrete for your slab, then, 270 / 27 =10 cubic yards of concrete.

Multiply the number of cubic yards by the strength you want the concrete to have. A "6-bag" mix is stronger than a "4-bag" or "5-bag" mix. If you want a 6-bag mix, then you will need six bags of cement per cubic yard of concrete: 6 x 10 = 60 bags of cement.

## How to Measure Concrete for 8' Sonotubes

## Step 1

Follow the link listed under Resources to Sonotube's volume chart.

## Step 2

Go down the left hand column (in grey) and find the diameter of the Sonotube you are using.

## Step 3

Move across the row to the right until you reach the column that lists the depth of an 8-foot Sonotube (three columns over from the diameter column). Note the concrete needed to fill the tube. The number given on the chart is in cubic yards, which is how concrete is sold. If you are mixing your own you, figure one 80 lb. bag of concrete will yield 1 cubic foot of concrete. (There are 27 cubic feet in a cubic yard.) Use the online calculator listed under Resources to help determine how many bags you would have to mix to yield the concrete in cubic yards listed on the chart.

## How Much Is a Yard of Topsoil?

Topsoil is sold by the cubic yard. According to the Oregon State Extension Office, 1 cubic yard of topsoil will cover an area of 50 square feet at a depth of 4 to 6 inches.

## How to Measure for Yard Mulch

Measure the length and width of your yard in feet. Then, multiply the two numbers together. This number equals the area of your yard.

Divide the depth you want the mulch (in inches) by 12 to convert it to feet. For example, if you want to lay 3 inches of mulch, divide it by 12. This equals a desired mulch depth of 0.25 feet.

Multiply the yard area from Step 1 and the desired mulch depth in Step 2; both calculations should be in feet. This equals the amount of mulch in cubic feet you need to cover your yard. To convert it cubic yards, divide by 27.

## How to Calculate Weight Per Cubic Yard of Gravel

Approximate the specific weight of your gravel based on the particle size. Gravel ranges from 85 to 125 lb. per cubic foot. Gravel with high percentages of small particles will have a higher specific weight, while gravel with high percentages of large particles will have a lower specific weight. You can use an average specific weight of 100 lb. per cubic foot in most cases.

Set up a unit conversion to convert from pounds per cubic foot to pounds per cubic yard. There are 27 cubic feet in a cubic yard, so for gravel with a specific weight of 100 lb. per cubic foot, use 100 lb. per cubic foot times 27 cubic feet per cubic yard.

Multiply the unit conversion to find the weight per cubic yard. For example, 100 lb. per cubic foot times 27 cubic feet per cubic yard equals 2,700 lb. per cubic yard. Cubic feet "disappears" from the result because, if you wrote the units in fraction form, cubic feet would appear in the denominator of pounds per cubic foot and in the numerator of cubic feet per cubic yard. This means the cubic feet cancel out when you multiply. In this example, if the gravel had a specific weight of 85 lb. per cubic foot, then 85 lb. per cubic foot times 27 cubic feet per cubic yard equals 2,295 lb. per cubic yard.

## How to Convert 1 Yard of Topsoil

## Instructions

Use the base definition of 1 yard equals 3 feet.

Define one cubic yard as 27 cubic feet. This is determined by changing the yard measurement into feet and then multiplying the "cube" height of three feet by the width of three feet by the depth of three feet: 3 x 3 x 3 = 27 cubic feet.

Convert the smaller quantities of cubic-foot measurements to determine the coverage area of a cubic yard. For example, if you needed 10 2-cubic-foot bags of topsoil to cover beds in previous seasons, they equaled 20 cubic feet. Since one cubic yard equals 27 cubic feet, divide 20 by 27. That produces an answer of .74 , meaning you need nearly three-fourths of a cubic yard of topsoil to cover the same beds.