Raised Bed Soil Calculator

Introduction

Building a raised bed garden is exciting, but figuring out how much soil you need can be tricky. Our Raised Bed Soil Calculator takes the guesswork out of the process. Just enter the length, width, and depth of your raised bed, and the tool will tell you exactly how much soil to buy. This saves you time, money, and extra trips to the garden center. Whether you are filling a single bed or planning a whole garden, this calculator helps you get the right amount of soil every time. No more buying too much or too little — just the perfect fill for healthy plants and strong roots.

How to Use Our Raised Bed Soil Calculator

Enter the size of your raised bed below, and this calculator will tell you exactly how much soil you need to fill it.

Length: Enter the length of your raised bed in feet or inches. Measure from one end to the other along the longest side.

Width: Enter the width of your raised bed in feet or inches. This is the shorter side of your bed.

Depth: Enter how deep your raised bed is in feet or inches. This is the height of the walls from the bottom to the top. Most raised beds are between 6 and 12 inches deep.

Results: The calculator will show you the total amount of soil you need in cubic feet and cubic yards. Cubic yards is the unit most garden centers and soil suppliers use when selling soil in bulk, so this number helps you know exactly how much to order.

Raised Bed Soil Calculator

A raised bed is a garden built on top of the ground, usually held in place by a frame made of wood, stone, or metal. Raised beds are popular because they give you better control over your soil, drain water more easily, and keep weeds out. They also warm up faster in spring, which means you can start planting sooner.

How Much Soil Do You Need?

Figuring out the right amount of soil for your raised bed is one of the most important steps before planting. If you add too little soil, your plants won't have enough room for their roots to grow. Too much soil can be a waste of money. This calculator helps you find the exact volume of soil you need based on the size of your raised bed. If you're also planning the layout of your garden, our Plant Spacing Calculator can help you determine the ideal distance between each plant in your bed.

Understanding Soil Volume

Soil volume is measured in cubic feet or cubic yards. To find the volume, you multiply the length, width, and depth of your raised bed together. Most raised beds are between 6 and 12 inches deep. A depth of at least 6 inches works for herbs and lettuce, but deeper beds of 12 inches or more are better for tomatoes, carrots, and other plants with long roots. If you need help determining the area of your bed before calculating volume, our Square Footage Calculator is a handy companion tool.

What Kind of Soil Should You Use?

The best soil mix for raised beds is a blend of three things:

• Topsoil – makes up the bulk of your bed and gives structure. Use our Topsoil Calculator to figure out exactly how much topsoil to purchase for your mix.
• Compost – adds nutrients that feed your plants
• Perlite or coarse sand – helps with drainage so roots don't sit in water. Our Sand Calculator can help you estimate the right amount if you choose to use coarse sand.

A common and trusted recipe is 60% topsoil, 30% compost, and 10% perlite or sand. This mix gives your plants a rich, well-draining home to grow in. You may also want to add a layer of pea gravel at the bottom of deeper beds to improve drainage further.

Helpful Tips

Keep in mind that soil settles over time. After filling your raised bed, the soil level can drop by 10 to 20 percent within the first few weeks. It's a good idea to buy a little extra soil so you can top it off later. Also, adding a fresh layer of compost each season keeps the soil healthy and full of nutrients for your next round of plants. If you're building up around your raised beds with landscaping, tools like our Mulch Calculator and Sod Calculator can help you plan the surrounding area. For those building a retaining wall to support tiered raised beds on a slope, be sure to calculate materials for that project as well.

Frequently Asked Questions

What depth should I use for my raised bed?

It depends on what you want to grow. Use 6 inches for shallow-root plants like lettuce, herbs, and radishes. Use 12 inches for beans, peppers, and cucumbers. For tomatoes, squash, and root vegetables like carrots, go with 18 inches or more. Deeper beds give roots more room and produce healthier plants.

How does the calculator handle circular raised beds?

Select the Circular shape tab on any bed entry. Enter the diameter (the distance across the circle) and the depth. The calculator uses the formula π × radius² × depth to find the volume. This gives you an accurate soil amount for round beds, tubs, or barrel planters.

What is the L-shaped bed option for?

The L-shaped option lets you calculate soil for beds that are not a simple rectangle. You enter the outer rectangle dimensions and then a cutout rectangle that gets subtracted. The calculator figures out the remaining L-shaped area and multiplies it by the depth to get your soil volume.

Can I calculate soil for more than one raised bed at a time?

Yes. Click the "+ Add Another Bed" button to add as many beds as you need. Each bed can have its own shape, size, and depth. The calculator adds up all the beds and shows you the total soil needed plus a per-bed breakdown.

How do I switch between imperial and metric units?

Use the Unit System toggle at the top of the calculator. Choose Imperial for feet and inches or Metric for centimeters and meters. The calculator will update all fields and results to match the unit system you pick.

What does the soil mix ratio section do?

It lets you set custom percentages for topsoil, compost, and perlite/vermiculite. The three values must add up to 100%. After you calculate, the per-bed breakdown table shows exactly how much of each ingredient you need for every bed.

Why does the calculator show bags in two sizes?

Soil bags come in different sizes. In imperial mode, the calculator shows how many 1 cubic foot bags and 2 cubic foot bags you need. In metric mode, it shows 28-liter and 57-liter bags. This helps you compare options and pick the best size for your budget.

How much extra soil should I buy to account for settling?

Soil settles about 10 to 20 percent after you first fill a bed. A safe rule is to buy 10 to 15 percent more than the calculator shows. This way you will have enough to top off your bed after a few weeks.

What if my raised bed has an unusual shape that is not listed?

Break your bed into simpler shapes. For example, a U-shaped bed can be split into three rectangles. Add each section as a separate bed entry in the calculator. The tool will total them all up for you automatically.

How do I convert cubic feet to cubic yards?

Divide cubic feet by 27. There are 27 cubic feet in one cubic yard. The calculator does this math for you and shows the result in the Cubic Yards card so you can easily order bulk soil from a supplier.

Can I use this calculator for container gardens or pots?

Yes. If your container is round, use the Circular shape and enter the diameter and depth. If it is a square or rectangular planter, use the Rectangular shape. The volume calculation works the same way for any container.

What does the Quick Fill by Plant dropdown do?

It automatically sets the depth field to the recommended minimum depth for the plant type you choose. For example, selecting "Tomatoes, squash, broccoli" sets the depth to 18 inches (or 45 cm in metric). You can still change the depth manually afterward.

Why is my mix percentage warning showing up?

The warning appears when the topsoil, compost, and perlite/vermiculite percentages do not add up to 100%. Adjust the numbers so they total exactly 100. The calculator needs this to correctly split the soil volume into each ingredient.