How Much Soil Do I Need?
Our handy soil calculator makes it quick and straightforward to calculate how much soil you’ll need for your garden.
From simple square or rectangular beds to more intricate designs consisting of circles, triangles, or even octagons, our soil calculator will help you determine the volume or weight of soil needed.
We’ve included a step-by-step user guide below the calculator that will answer any technical queries. You’ll also find several calculation guides showing you how to calculate the quantity of soil needed for several real-life examples if you’d prefer to calculate these manually.
How to Use the Soil Calculator
With our soil calculator, you can calculate the volume or quantity of soil required for various area shapes. You can choose the relevant profile for your calculation using the ‘Select a Soil Profile’ dropdown.
The following profile types are available via the dropdown:
Use the ‘Soil Type’ dropdown in box (2) to choose the type of soil for your calculation, with the following types being available:
- General Soil
- Chalk Soil
- Clay Soil
- Loam Soil
- Peat Soil
- Sandy Soil
- Silt Soil
You can find out more about the various types of soil later in the article, but if in doubt, we’d recommend sticking with the ‘General Soil’ option.
You can also choose ‘Custom Soil’ if there’s a specific type of soil that you’d prefer to use.
The ‘Density’ box will automatically be populated based on the type of soil you choose.
You can update the ‘Density’ figure if needed, although this is based on industry guidance for each material.
We would recommend using a custom density value, however, if you have a specific value available from the supplier of a type of soil you’re planning to use.
Depending on the soil profile chosen, you’ll need to enter various dimensions, for example, ‘Length’, ‘Width’, and ‘Diameter’. You’ll also need to enter the planned ‘Soil Depth’ value in the relevant input box.
The calculator will automatically reformat depending on the soil profile type chosen, meaning only the relevant dimensions will be shown.
You can select the relevant units (in both metric and imperial) for each measurement using the ‘Unit’ dropdowns.!
Note: If you choose ‘inch’ as a unit, you’ll need to use either whole or decimal numbers instead of fractions. For example, 0.50 instead of 1/2.
- Use the ‘Calculate’ button to complete the calculation, and the ‘Reset’ button to reset the soil calculator.
How to Calculate How Much Soil You Need
The easiest way to calculate how much soil you need is by using our handy calculator above.
If you’d prefer to calculate the volume or quantity required manually, though, you can do so via the following equations:
First, you’ll need to calculate the volume of soil you need using the following equation:
Once you’ve calculated the volume of soil required, you can then multiply this via the density of your chosen soil to work out the weight of soil required. For example:
We’ve provided sample densities for various soil types in the calculator above, but for the most accurate calculation, we’d recommend using the density value supplied by the manufacturer or supplier of your soil.
These equations remain the same whether you’re working with metric units like meters or imperial units like feet or yards.
Let’s look at some real-life example calculations to show you step-by-step how to work out how much soil you need:
- How Much Soil Do I Need per Square Foot?
- How Much Soil Do I Need for Pots?
- How Much Soil Do I Need for a Raised Bed?
How Much Soil Do I Need per Square Foot?
It’s relatively easy to calculate how much soil you require per square foot, although you will need to know how deep you want your soil layer to be.
It’s probably stating the obvious, but you’ll require more soil per square foot for a 4-inch deep than a 3-inch deep layer.
The calculation to work out the quantity or volume required is as follows:
When calculating the quantity of soil required per square foot, the equation consists of the following elements:
V = Volume
A = The area of soil
D = The depth of soil
Let’s work through an example of a 6-inch deep layer of soil.
The soil area for this example is a square foot, based on a profile that is one foot in both length and width.
Because we’re working on the basis of square feet, we’ll need to convert the soil depth (currently in inches) to feet, which you can do by dividing the inch dimension by 12 (6″ / 12 = 0.5 feet for this example).
Here’s how the calculation works:
Volume = 1 ft2 x 0.5 ft
Volume = 0.5 ft3
Therefore, you would need approximately 0.5 ft 3 to cover each square foot based on the required soil depth of 6-inches.
To summarise, the basic concept for finding the amount of soil required per square foot is to multiply the square foot area by the depth measurement converted to feet. Doing so will leave you with the amount needed in cubic feet for whatever soil application you need, from pots to raised beds to new lawns.
How Much Soil Do I Need for Pots?
The above calculator functions well as a potting soil calculator or as a soil calculator for pots, but it is straightforward to work out how much soil you’ll need manually if preferred.
For cube-shaped pots, you’ll need to use the following equation to work out the internal volume of the pot:
It’s worth remembering that you might not want to fully fill the pot with soil, and so you’ll need to reduce the height measurement by one or two inches to leave a gap at the top of the pot.
For example, in the case of a pot that is 16-inches (i.e., 1.33 feet) in all dimensions (length, width, and height), where we want to leave a 2-inch gap (i.e., 0.17 feet) at the top of the pot:
Overall Soil Volume = Length x Width x Height
Overall Soil Volume = 1.33 x 1.33 x (1.33 – 0.17)
Overall Soil Volume = 2.05 ft3
Therefore, you would need just over 2 ft3 to fill a cube-shaped pot with an internal length, width and depth of 16-inches (assuming a gap of 2-inches at the top of the pot).
For cylindrical-shaped pots, you’ll need to use the following equation to calculate how much soil the pot can hold:
While it may look complicated, the above equation is relatively simple and consists of the following elements:
V = Volume
π = Pi, or 3.142
r = The internal radius of the pot, squared
d = The internal depth of the pot
Again, it’s worth remembering that you might not want to fill the entirety of the pot with soil, in other words, leaving a gap between the top of the soil and the pot’s rim.
For example, in the case of a pot that has an internal radius of 12-inches (i.e., 1 foot), an internal depth of 18-inches (i.e., 1.5 feet), and where we want to leave a 1-inch gap (i.e., 0.08 feet) at the top of the pot:
Overall Soil Volume = (Pi x (Radius x Radius)) x (Internal Depth – Top Gap)
Overall Soil Volume = (3.142 x (1 x 1)) x (1.5 – 0.08)
Overall Soil Volume = 4.46 ft3
Therefore, you would need just under 4.5 ft3 to fill a cylindrical pot with an internal radius of 12-inches, and an internal depth of 18-inches (assuming a 1-inch gap at the top of the pot).
How Much Soil Do I Need for a Raised Bed?
It’s straightforward to create your own raised bed soil calculator using a spreadsheet, or you can manually calculate the amount of soil required.
Regardless of your approach, there is only one equation needed to calculate the volume of soil required for a rectangular-shaped raised bed, for example.
The equation is as follows:
It’s worth remembering that you might not want to fill the raised bed fully, and so you’ll need to reduce the height measurement by the desired amount (for example, two or three inches) to leave a gap between the top of the soil and the edge of the raised bed.
For example, in the case of a raised bed that is 6-feet in internal length, 3-feet in internal width, and 2-feet in internal depth (assuming we want to leave a 3-inch, or 0.25 foot gap at the top):
Overall Soil Volume = Length x Width x Height
Overall Soil Volume = 6 x 3 x (2 – 0.25)
Overall Soil Volume = 31.5 ft3
Quick Reference Information
- What is Soil?
- Types of Soil
- Soil vs Dirt: What’s the Difference?
- How Deep Should Topsoil Be?
- How Much Soil Is in a Yard?
- How Heavy Is Soil?
What Is Soil?
Soil is the loose, brown layer of material that covers the Earth’s surface, and it consists of various minerals, air, water, and micro-organisms.
Soil provides the physical support needed by plants and the water and nutrients they require for growth, and it also provides a habitat for various animals. Without soil, Earth would not be able to sustain life.
Types of Soil
Soils not only consist of a complex and varied mixture of minerals, air, water, and micro-organisms, but external factors such as leaching and weathering can also alter their chemical and physical properties.
Because of this, various soil types exist, and each one has strengths and weaknesses depending on what you want to do with it.
Here’s a summary of some common soil types:
- Chalk Soil – Chalky soils usually contain more stones than other soil types, making them drain more freely. Usually found over chalk or limestone bedrocks, chalky soils are alkaline and may require a pH balancer to prevent growth issues for plants.
- Clay Soil – Clay soil consists of over 25% clay and is well known for poor drainage that causes it to dry out slowly. It is typically wet, cold, and sticky during the winter months and tends to crack during the warmer summer months. Clay soil is generally heavy and hard to dig, making it problematic for gardeners.
- Loam Soil – The ‘goldilocks’ of soils, loams consist of a mixture of sand, silt, and clay to provide high-quality, free-draining, and nutrient-rich soil that is easy to work. It’s possible to further categorize loams as sandy or clay, depending on their consistency.
- Peat Soil – Rarely found in gardens, peat soil is darker in color and tends to become waterlogged, often requiring additional drainage. It is acidic in nature, and although it is high in organic matter, it tends to be low in nutrients as the soil’s acidity slows down decomposition.
- Sandy Soil – Sandy soil feels gritty to the touch. It is worked easily and drains quickly, although this can lead to vital nutrients leaching away. Sandy soils often require large amounts of organic matter to be added to help retain moisture and feed plants.
- Silt Soil – Silty soils consist of relatively fine particles, and they feel smooth to the touch and are easily compacted. Silty soils drain well but hold more moisture than sands, making them higher in nutrients than sandy soils.
Soil vs Dirt: What’s the Difference?
While soil and dirt may look similar, there is a distinct difference between the two.
Soil is classed as ‘alive’ due to the various living organisms it contains, including insects and microorganisms, and different nutrients and minerals that support life and plant growth.
Dirt, however, mainly consists of inorganic matter such as sand, silt, clay, and rocks. Dirt can be classed as ‘dead’ as it doesn’t have the insects, microorganisms, nutrients, or minerals found in soil that are needed to support life or plant growth.
How Deep Should Topsoil Be?
Generally, the deeper the layer of topsoil, the better when it comes to providing the best environment for plant growth. A deeper layer of topsoil will allow plants and trees to develop a stronger and more stable root system, which will keep them supported and with a good supply of moisture, air, and nutrients as they grow.
When filling a planter or garden bed, we’d recommend a minimum layer of 10-inches for your topsoil.
If you’re installing a new lawn, we’d recommend spreading a 4-6 inch layer of topsoil over the existing soil before sowing seed or laying sod.
In general, the better the quality of the sublayer of soil, the shallower your topsoil layer can ultimately be.
How Much Soil Is in a Yard?
Here’s an approximate guide to how much coverage you can expect from one cubic yard of soil:
1 Cubic Yard Soil Coverage
|Soil Depth||Approximate Coverage|
How Heavy Is Soil?
The weight of soil per cubic yard will vary depending on several factors, including the type of soil, how compressed it is, and the moisture content of the soil.
The weight per cubic yard will be higher for more compressed (i.e., packed more tightly) or wetter soil.
Here is a summary of the average weight of a variety of soil types:
Weight of Soil per Cubic Foot
|Soil Type||Average Soil Weight Per Cubic Foot|
|Chalk Soil||83.87 lbs (38.04 kg)|
|Clay Soil||82.62 lbs (37.48 kg)|
|Loam Soil||88.83 lbs (40.29 kg)|
|Peat Soil||86.97 lbs (39.45 kg)|
|Sandy Soil||88.83 lbs (40.29 kg)|
|Silt Soil||85.73 lbs (38.89 kg)|
Weight of Soil per Cubic Yard
|Soil Type||Average Soil Weight Per Cubic Yard|
|Chalk Soil||3,892.85 lbs (1,765.72 kg)|
|Clay Soil||3,835.11 lbs (1,739.56 kg)|
|Loam Soil||4,123.33 lbs (1,870.35 kg)|
|Peat Soil||4,036.96 lbs (1,831.11 kg)|
|Sandy Soil||4,123.33 lbs (1,870.35 kg)|
|Silt Soil||3,979.22 lbs (1,804.96 kg)|
Weight of Soil per Cubic Meter
|Soil Type||Average Soil Weight Per Cubic Meter|
|Chalk Soil||1,350 kg (2,976.32 lbs)|
|Clay Soil||1,330 kg (2,932.18 lbs)|
|Loam Soil||1,430 kg (3,152.54 lbs)|
|Peat Soil||1,400 kg (3,086.50 lbs)|
|Sandy Soil||1,430 kg (3,152.54 lbs)|
|Silt Soil||1,380 kg (3,042.36 lbs)|