How to Calculate Soil for Raised Beds

How Much Soil Do I Need for Raised Beds?

After installing over 300 raised bed kitchen gardens with my company, Rooted Garden, I have learned the hard way that doing the math correctly can make the difference in running out of soil or having way too much for your raised beds.

The main measurement you need to calculate for your raised beds is the cubic feet of your garden. To calculate cubic feet, you need to first determine the square feet of your garden. This is simply the length times the width of your garden bed.

Then, to get the total cubic feet of each raised bed, simply multiply the square feet of your garden's footprint by the height of your raised bed garden. This provides the total cubic feet of garden space that must be filled with soil.

Here's a simple soil calculator to add up exactly how much soil you need to fill up your raised bed garden:

STEP 1:

Calculate the total width of your garden in feet = W

STEP 2:

Calculate the total length of your garden in feet = L

STEP 3:

Calculate the total height of your garden in feet = H

STEP 4:

Multiply all three together: W x L x H

The answer for this equation is the TOTAL CUBIC FEET of soil you need for your raised beds.

How to Calculate Soil for Raised Beds

Now that you know the main calculation, you need to determine how much soil is required for your raised beds. Let's look at some example raised bed gardens so the soil calculation makes sense.

How to Calculate Soil for 2.5' x 7' x 2' Raised Garden Beds

First, let's consider my own kitchen garden that's made of six raised garden beds each measuring 2.5' x 7' x 2'.

This Double Garden Trio is the feature of my book, Kitchen Garden Revival.

To calculate the cubic feet of each bed, we'll use our soil calculator:

2.5 x 7 x 2 = 35 cubic feet for each bed

Because this setup includes six gardens that all have the same measurement, the total calculation for the full amount of soil needed for these raised beds is:

6 x (2.5 x 7 x 2) or 6 x (35) = 210 cubic feet

How to Calculate Soil for 4' x 4' x 1' Raised Garden Bed

In the case of the $100 bed, the calculation looks like this: 

4' x 4' x 1' = 16 cubic feet

How to Make Modifications to Your Raised Bed Soil Calculations

You may want to change the height of your 4' x 4' garden or you may want to have several raised beds that are all the same measurements.

Here's how to adjust the calculator based on those changes in your raised bed setup.

If you halved the height of that garden, it would be this instead:

4' x 4' x .5' = 8 cubic feet

And if you doubled the height of the garden, it would be this:

4' x 4' x 2' = 32 cubic feet

If you have more than one garden that's the same size, you'll just multiply the total cubic feet per bed by the number of beds.

Here's the Soil Calculator for two raised beds that are both 4' x 4' x 1'.

2 x (4' x 4' x 1') = 32 cubic feet

How to Calculate Soil for 4' x 4' x 2' Raised Garden Beds

Now, let's consider this Four Garden Classic set up for my Rooted Garden client in River Oaks, Houston, Texas.

This Four Garden Classic is created with four raised gardens that each measure 4' x 4' x 2'.

To calculate the cubic feet of each bed, we'll use our soil calculator:

4 x 4 x 2 = 32 cubic feet for each bed

Because this set up includes four gardens that all have the same measurement, the total calculation for the full amount of soil needed for these raised beds is:

4 x (4 x 4 x 2) or 4 x (32) = 128 cubic feet

When to Use Soil Bags to Fill Your Raised Beds

Once you know how much soil you need for your raised bed gardens, you need to decide if you'll use soil bags or get a truck delivery of soil.

Generally, soil bags come in one cubic foot measurements. Larger bags are sometimes available in two cubic foot measurements. Once you pass 27 cubic feet of soil needed for your raised beds, you are now talking about yards of soil, instead of cubic feet. 

If you need less than 27 cubic feet of soil for your raised bed garden, you'll want to purchase soil bags to fill your garden instead of ordering a truck delivery of soil. 

How to Know When You Need a Truck Delivery of Soil

As soon as you reach more than 27 cubic feet of soil needed for your raised beds, you'll have to decide between ordering a truckload of soil or purchasing individual bags.

When your soil need is between 27 and 54 cubic feet, it can be difficult to get a soil company to deliver soil to you, as their minimum order is generally 2 total yards of soil (or 54 cubic feet).

But it's likely better for you to order a truckload of soil instead of purchasing bags, especially if you pass 50 cubic feet of soil, which is about 2 yards of total soil.

In summary, if your total garden area is going to be less than 54 cubic feet, you'll probably need to go with bag soil. But if your total garden area is going to be greater than 54 cubic feet, it's much better to order a truck delivery of soil for your raised beds. 

Now, of course, if you have your own truck, you can put as little or as much soil as you need in the back of your truck. I've just got a minivan, but if you have a truck, you can likely get a load of the soil amount you need right into the bed of your truck. 

Choosing Between Bagged Soil and a Truck Delivery

Sometimes it can be difficult to choose whether you should purchase bags or get a truck to deliver the soil you need for your raised beds. 

The benefits of using soil bags for a smaller amount of soil is that they're easier to install and it's usually possible to pick them up in your own car. You won't have the big mess of a large soil delivery, and you'll be able to time the delivery of the soil just right because you'll be the one picking the soil bags up. Plus, you can make your own soil blend by choosing a wider variety of soil mixtures depending on which soil bags are available where you shop. 

A truckload of soil for your raised beds is typically needed for a larger amount of soil. Trucks make the soil much less expensive per unit, and delivery from the company is usually possible. You have the benefit of saving the wear and tear on your vehicle and the pain of hauling the soil bags yourself. Getting a truckload of soil can also make it possible for you to order more soil than you need in case you want to extend your garden project into other parts of the landscape. 

The Cons for Using Soil Bags for Your Raised Bed Garden

The cons for a bag is that it's much more expensive. In my area, good sandy loam soil can run as much as $14 per cubic foot for a bag. There's also a lot more waste. As you know, each one of those bags is a big piece of plastic that's going to be thrown away. Finally, the bags can be pretty heavy for your vehicle. I've loaded as many as 30 bags into my van before, and my van was definitely showing the wear and tear from the weight. You'll want to be sure that your car can carry that much weight depending on how many bags you'll need. 

The Cons for Using Truck Delivery for Soil for Your Raised Bed Garden

A truck delivery can be kind of messy because it’s going to dump soil all over your driveway or your yard before you can install it into your garden. It is also more difficult to install because you've got to do a lot of shoveling and there is also a chance of miscalculation. Because they are not taking it wheelbarrow by wheelbarrow into the truck to determine your yardage for the soil, I've had it happen quite a few times that I got way too much soil or way too little from a truck delivery. 

How to Prepare for Soil Delivery for Your Raised Beds

Once you've calculated how much soil you need for your raised beds and whether you will use soil bags or a truck delivery, it's time to prepare for the soil pick up and installation. 

First, you want to be sure that your garden is fully constructed and installed.

You also want to know that your irrigation is in place—you don't have to have your drip tubes down, but you do need to have the source for irrigation connected through a pipe.

Finally, you want the route for installation to be clear, especially if you're using wheelbarrows to get the soil from the place it's dumped to the garden. 

If you're using bags of soil for your raised beds, you want to have a good place to set up all those bags upon delivery. If you're picking up bags, you want to be sure and call ahead to make sure the store has an adequate supply. I can't tell you how many times I've gone to the nursery ready to grab my bags of soil only to discover they were out of the type I wanted. You also want to make sure your vehicle can hold the weight and put some kind of protection in your vehicle like a tarp or plastic bags, something to keep that dirt out of your car. 

If you're using a truck delivery, you want to make sure that your garden requires the minimum yardage for the truck delivery. Most truck deliveries need to be at least two yards, and some even require them to be three, so call ahead and be sure that you've got a need for as much soil as they're requiring you to get. 

You also want to make sure there's vertical clearance for your dump truck. These dump trucks generally are going to go up pretty high in the air to dump all that soil out. Make sure that you have a spot in your landscape where it can do so. 

Finally, you want to get approval to dump the soil. Depending on your neighborhood, you might have to get approval from an HOA or a club to be sure that it's okay to put soil on the street or somewhere in your landscape. 

How to Install Soil Into Your Raised Beds

Now, you're finally ready to install soil into your raised garden beds. 

The tools you will need are a box cutter or knife, a rake, trash bag, a blower or broom, and a water hose. 

For truck delivery, you might want to place a large tarp under the soil before it's dumped out to make cleanup on your driveway much easier.

A snow shovel is really helpful to get under that soil to put it into the garden. 

To install the soil, you want to slowly fill your raised beds, three to six inches at a time, being sure to protect your water source as you do. Put something like a piece of plastic or cloth on top of the pipe that's coming up to be sure you don't get dirt down into it. 

As you install every four to five inches of soil, you want to wet the soil thoroughly so that you can continue to fill it up.

Finally, you want to level your soil with a rake. 

Raised Beds Soil Mix

Now that you know how to calculate your soil for your raised beds, it's time to think about what that soil mix should be.

For years, I've used a sandy loam garden soil that's organic and natural and that doesn't include any peat moss products.

If you want more help how to create the soil blend, how to keep your soil healthy, and how to blend a variety of natural soil ingredients to get the best organic mix, all of that is inside of our gardening course, Kitchen Garden Academy.

If you're still unsure how deep you'd like your raised beds to be, check out our guide for choosing raised bed depth based on the types of plants you'd like to grow.

Happy growing!