Applying mulch to a garden or area, or filling a hole with soil involves working out how much of either you need. An area of mulch will have a height usually at least about 1 inch (2.5 cm), as well as somewhere you are filling with soil. In this article, I will cover how to calculate how much mulch or soil you will need based on the area you are covering or filling, as well as the height that you want the soil or the mulch to be.
In general take the area in square feet and multiply it by the height in inches, multiplied by 0.083. This will give you the volume of soil or mulch in cubic feet. For example if the area is 5 sq feet, and the height is 3 inches, calculate 5*3*0.083. Which equals 1.245 cubic feet of mulch or soil.
For calculating it in the cm’s and meters simple calculate the volume in meters (width times length times height, w * l * h), doing so will give you the volume in cubic meters. Below I will cover some examples to ensure you’re making the calculations correctly, how to calculate how much it will cost in total if you are having contractors install it for, such as the cost of labor, and hauling it to your property.
How to Calculate How Much Mulch and Soil Is Needed
While it’s generally not possible to get the perfect amount of mulch or soil, you can calculate how much you will need so that there is very little left over. That way you won’t pay too much for the soil or mulch and won’t have extra work to find somewhere to put the extra soil or mulch. To do it’s best to use a simple calculation recommended by soil and mulch producers, here is how to calculate the total volume of soil or mulch you will need in cubic feet or cubic meters.
As a general rule, multiply the area in square feet by the height of the mulch or soil and multiply it by 0.083, this will give you the volume of soil or mulch you should get in cubic feet of mulch. For the volume and area in the metric system (cm’s and meters) simply calculate the volume.
Here are some examples so you can ensure you are calculating it correctly. First using inches and feet here is the calculation you want to do.
1. Calculate the area (width * height) in feet, write this down somewhere
2. Calculate the height of the soil or mulch in inches, write this down somewhere
3. Multiply both these numbers together
4. Multiply the number you got in 3 by 0.083, this is the volume in cubic feet.
Let’s say you want to fill a planter box that is 3 feet by 2 feet, and is 2.5 feet high.
Using the steps above.
1. Area = 3 * 2 = 6 sq feet
2. Height = 2.5 feet
3. 6 sq feet * 2.5 feet = 15
4. 15 * 0.083 = 1.245 cubic feet of soil or mulch
Rounding it you get about 1.25 cubic feet, or 1.3 cubic feet depending on how accurate you want to be. Next let’s say you want to apply mulch around 2 large trees.
You want the mulch to extend out from the tree by 3 feet in a circle, and you want the mulch to be 2 inches thick. It’s easiest to calculate it for one tree first and then simply get double that amount.
1. Area = π * r² = π*r*r = π*3*3 = 28 sq feet
2. Height = 2 inches
3. 28 sq feet * 2 inches = 56
4. 56 * 0.083 = 4.648 cubic feet of mulch
In this case because you’re applying mulch around two different trees you get double what you calculated = 4.648 * 2 = roughly 9 cubic feet of mulch.
How to calculate the volume of soil or mulch in cm or meters
Volume using the metric system (mm, cm, and m) is a bit easier. You simply calculate the volume. As you may remember from geometry class volume is width, times length, times height.
You may also remember that it’s not important what order the numbers are in when you are multiplying. So you can do height times width times length. The main thing to be aware of is to have all of the measurements in meters.
For example, if the depth you want is 5 cm, convert it to meters by dividing it by 100. There are 100 cm in 1 meter. So 5 cm is 0.05 meters.
Remembering that half a meter 0.50 is 50 cm. Here’s an example to make sure you’re doing it right. Let’s say you want to fill a planter box that is 2 meters wide, 3 meters long, and is half a meter high. The volume of the planter box is the width * length * height = 2 * 3 * 0.5 = 3 cubic meters, or 3 m3.
How to Calculate Cost of Mulch and Soil
Now that you know how much soil or mulch you will need based on the size of the area you want to fill or cover, the next step is to calculate how much the soil or mulch will cost. Here is how to make this calculation.
Overall, you calculate the volume of soil or mulch you need, and multiply that by the cost per cubic foot (or cubic meter). In some cases the mulch or soil you will want to get is in a bag, such as a 3 cubic foot bag of compost. If so, divide the volume of soil you need by the volume of the bag.
Here’s a few examples so you can ensure you’re doing it right. Let’s say you calculate you need 10 cubic feet of soil. But, the soil is sold in bags that are 2.5 cubic feet each.
Take 10 and divide it by 2.5. Which equals 4. So, you need 4 bags. Then multiply the cost per bag by the amount of bags you will need.
Let’s say you need 4 bags and each bag is $15. The total cost will be 4 * 15 = $60. Whereas, let’s say mulch is $2 per cubic foot. And you need 9 cubic feet.
Then the total cost will be $2 * 9 = $18. In some cases you may only need a very small amount of soil such as for potted plants. When you do the calculation you may end up with a decimal which can be a bit confusing.
Copyright protected content owner: ReadyToDIY.com and was initially posted on 2022-12-28.
For example, let’s say you need 2 cubic feet of compost for a few potted plants. But, the bags of compost you want to get are 2.5 cubic feet each. Doing the calculation you get 2 divided by 2.5 = 0.8, this is equal to just under 1 bag.
If you’re familiar with working with percentages you will know this is 80% of a bag. Often it involves 2 to 3 separate calculations to arrive at a total cost. There are also a few additional calculations that are required for areas that are circular or are not a regular square or rectangle.
Below are each of these calculations. Here is a helpful formula which most people don’t know off the top of their head for calculating the volume of a cylinder:
- Volume of a cylinder, for potted plants and circular shapes, such as mulch around a tree = π*r*r*h
How to Calculate Cost of Mulch and Soil Project
There are a few additional costs involved in a mulch or soil project such as the cost to get the mulch or soil to your property, and the cost of labor if you are having a few people or some landscape contractors help you with the project. Below, is how to calculate the total cost of a mulch or soil project, and all the associated costs you should include in your calculation.
In general, first calculate the cost of the mulch and/or soil, the cost of the tools you will need, the cost of labor, and the cost of haulage such as trailer hire, and petrol. Add these all together to give a total cost. Below is how to calculate each of these:
- Cost of a trailer – $75 to $150 per night
- Cost of labor – 30 minutes for every cubic foot
- Cost of tools (shovel, rake, wheelbarrow) – $100
- Cost of mulch or soil – Depends on area to be filled/covered
After that you will get a total. Mulch and soil are fairly easy to spread yourself, but can involve crouching down, and after using a shovel for half an hour or so you do get tired.
The cost to hire a landscaper. The lowest price for a landscape laborer is in the range of $17 per hour.
Other Things to Consider When Estimating Mulch and Soil Project
Adding soil or mulch to a garden or property is very common. The soil or mulch often needs to be hailed to the location using a trailer, or delivered by a truck. But, here is everything you need to consider when estimating the cost of a mulch or soil project.
Overall, provided you first find the volume of mulch or soil you need, estimating the cost of a soil or mulch project is very easy. The other considerations are whether you need to compact the soil. Typically, this is only required for soil installed before building foundations.
If you are adding additional soil for concrete footings, or building foundations, then talk to your local codes compliance office to see what pressure the soil needs to be. It’s widely known that if soil is not compacted it takes anywhere from 2 to 7 years to settle, and compact completely (source).
Copyright article owner is ReadyToDiy.com for this article. This post was first published on 2022-12-28.
In general, find the volume of the area you want to cover or fill with soil. Using the formula for volume, length * width* height. Take the volume of mulch or soil and multiply that by the cost per cubic ft of the mulch or soil.
ReadyToDIY is the owner of this article. This post was published on 2022-12-28.