How Much Soil For Raised Bed: Tips On How To Calculate Soil Needed For A Raised Garden Bed


How does someone knows exactly how much soil for raised bed, they need to purchase to avoid waste?

Many of us possess extra garden soil cluttering our backyards, which means that a lot of us require to buy more before it can be used in raised beds.

There are, however, soil volume formulas to assist you to determine actually what you require based on the size and form of your bed. So, we have shared several formulas to calculate the amount of soil required for various shapes of soil.

How to measure that how much soil for raised bed is required

Here is the simple formula to calculate how much soil for a raised bed in rectangular or square beds is. It requires just three side measurements: the width, length, and height of your bed.

The formula is as follows:

Volume = Length x Width x Height

V = the volume of the soil

L = the length of the bed

W = the width of the bed

H = the height of the bed


  1. Measure the width, length, and height of the bed. (Don’t worry about inside/outside measurements unless the boards are really thick.) Convert the measurements to a single unit. If the length of your bed is 6 feet, the width is 3 feet broad, and the height is 16.5 inches, for example, convert the inches to feet so that you have 6 x 3
  2. Multiply all of the measurements: 25.2 cubic feet = 6 x 3 x 1.4
  3. The answer to this problem is 29, which you can divide by 27 to obtain the total number of cubic yards. As it is clear from the above example, your bed would require 0.9 cubic yards of dirt.

L-shaped beds require a special formula to calculate soil volume.

Now, let’s see how to find how much soil for a raised bed for an L-shaped bed entails yet another procedure, but it’s not hard. Begin by dividing the bed into two figures that have four sides each using pencil and paper. For instance, to find out how much dirt you’ll need for an L-shaped yard:

To calculate each of these two estimates, use the equation above for the rectangular bed to compute them separately. Combine the results.

V = (L x W x H) + (L x W x H)

V = (6 x 3 x 1.4) + (3 x 3 x 1.4)

V = 25.2 + 12.6

V = 37.8 ft3

Divide by 27 to convert from cubic meters to cubic yards.

There are 1.4 cubic yards of dirt in the entire yard.

The amount of how much soil for raised bed you need for beds that are U-shaped

Create three individuals out of your U-shaped bed and compute each one using the square and rectangular formula. For example:

V = (L x W x H) + (L x W x H) + (L x W x H)

V = (9 x 4 x 1.4) + (3 x 4 x 1.4) + (3 x 4 x 1.4)

V = 50.4 + 16.8 + 16.8

V = 84 ft 3

To convert to cubic yards, multiply by 27.

The final measurement is 3.1 cubic yards.

Calculating the amount of soil required for hexagon-shaped beds

A hexagonal prism is a shape formed by six rectangular raised beds. There are two types of hexagonal prisms: regular and irregular. To determine how much soil for raised bed is required to fill how much soil for raised bed in a regular hexagonal bed, use the following calculation.

V= 3/2 (√3) s2h

V = total soil volume

S = length of the one side of a regular hexagon

H = height of the bed

Here is an example

V= 3/2 (√3)(32)(2)

V = 46.77 ft3

You can use the formula below to determine how much debris you need in terms of cubic yards.

For a quick way to estimate the volume of any triangle, try this online calculator for standard hexagonal prisms.

Calculating the volume of how much soil for raised bed of octagonal shape

An octagonal prism is a form produced by octagonal raised beds. As with the previous example, these beds come in standard irregular octagons (where all of the sides are identical). To calculate how much soil for raised bed is required to fill a regular octagonal bed, use this equation.

V = 2 (1 + √2) S2H

V = total soil volume

S = length of one side of the regular octagon

H = height of the bed

Here is an example

V = 2 (1 + √2)(32)(1.4)

V = 60.84 ft3

To figure out how much space there is in the garage, divide the total amount by 27.

You can also use online calculators for calculations too.

Finding how much soil for raised bed is required for on-rectangular shapes

If you’re familiar with a volume estimation, you can consider your long octagon (or hexagon) to be a rectangle and use the above-mentioned formula to gauge how much soil for raised bed you’ll need to calculate the volume for the corresponding four-sided figure.

If you want to be even more precise, there is another alternative. To discover the volume of any bed that has an irregular, first, determine the area of the bed and then multiply that figure by the height. You may break down your large hexagon or octagon into rectangular and obtain each area. To calculate that how much soil for raised bed is required, add the total of all three bases together for the foundation area, then divide by the height. This will provide you with the cubic measurement you’ll need for soil volume. (To determine the area of a triangle using half of the base and height, multiply.

Accurately measuring odd-shaped beds

Some beds, however, differ considerably from one another in terms of inside and outside dimensions. In these cases, it’s preferable to take your measurements from within rather than risking having too much garden soil.

A mortise and tenon method is used to make Farmstead beds. The board’s extremities are considerably larger than the interior measurements due to this construction.

It’s all about getting it right.

So, you can use any of the above formulas to calculate how much soil for raised bed. Knowing the correct soil volume can help you save time and money. You’ll not only make the greatest use of your area by filling your beds properly, but you’ll also give your plants the room they require to thrive.

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