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Ready to fill a new raised bed or container? Our Soil Calculator makes it easy to get started! Just plug in your raised bed or pot dimensions, and we’ll tell you exactly how much soil you need—and the perfect mix to help your plants thrive. We've taken the guesswork out, so you can stop digging for answers and start digging in.
Soil Calculator
Area 1
Raised Bed
Pot (circular)
Area
Raised Bed
Pot (circular)
How to Use the Soil Calculator
For Raised Beds
Simply enter your raised bed’s inner length and width, as well as its depth. (Example: 8 feet long × 4 feet wide × 12 inches deep.)
Add multiple beds if needed.
The calculator will provide the total volume in cubic feet, plus a soil mix breakdown of how many bags of topsoil, compost, and sand to buy (based on standard bag sizes).
You can also view the volume in cubic yards if you're having soil delivered by the truckload.
Enter the diameter (measured across the top of the pot) and depth.
Add multiple pots if needed.
The calculator will tell you how much potting soil you need and suggest the number of bags (usually sold in 1.5 cubic foot sizes).
Why Soil Matters in Raised Beds and Containers
Raised beds allow you to control soil quality—especially helpful if your native soil is compacted, nutrient-poor, or drains poorly. A proper mix ensures your vegetables and herbs get the ideal balance of structure, moisture, drainage, and root support.
20% coarse sand (or perlite) – for drainage and airflow
You can buy ready-mixed “raised bed soil” at garden centers, but it’s often more cost-effective to mix your own using local topsoil, quality compost, and coarse sand.
Best Soil for Containers
Containers are even more constrained, so your soil needs to work harder. A lightweight, well-draining potting mix is essential. You can buy pre-mixed bags or make your own potting mix using compost, peat or coconut coir, and perlite.
FAQs: Raised Bed Soil 101
What’s the Best Size for a Raised Bed?
A popular size is 4 feet wide Ă— 8 feet long Ă— 12 inches deep, offering 32 square feet of growing space.
Keep the width at 4 feet or less so you don’t step on the soil. Length is flexible, though beds longer than 12 feet can become inconvenient to walk around and water. Heights vary: 6 to 12 inches is common when using the ground below, but raised or above-ground beds require more soil (and cost more). Learn more about the best height for you.
How Deep Should Soil Be In a Raised Bed?
For most vegetables, aim for 12 to 18 inches of soil depth to accommodate root systems. Shallow-rooted crops like lettuce can grow in 6 inches, but deeper-rooted crops like carrots or tomatoes need more. Without enough depth, your carrots may grow sideways! See how to build a raised bed!
Shallow Rooting 12" - 18"
Medium Rooting 18" - 24"
Deep Rooting 24" - 36"+
Arugula
Beans, dry
Artichokes
Broccoli
Beans, pole
Asparagus
Brussels sprouts
Beans, snap
Beans, lima
Cabbage
Beets
Okra
Cauliflower
Canteloupe
Parsnips
Celery
Carrots
Pumpkins
Chinese cabbage
Chard
Rhubarb
Corn
Cucumber
Squash, winter
Endive
Eggplant
Sweet potatoes
Garlic
Kale
Tomatoes
Kohlrabi, Bok Choy
Peas
Watermelon
Lettuce
Peppers
Onions, Leeks, Chives
Rutabagas
Potatoes
Squash, summer
Radishes
Turnips
Spinach
Strawberries
What’s the Difference Between Raised Bed Soil and Potting Soil?
Raised bed soil includes topsoil for structure and is heavier. Potting soil is lighter and fluffier, designed for containers. It often lacks nutrients or the volume needed for raised beds unless amended. (Learn more about how potting soil is different than topsoil.)
Can I Use In-Ground Soil for Raised Beds?
Not recommended. Native soil is often too dense or lacks nutrients. If you must use it, amend heavily with compost and sand to improve texture and fertility.
What Should I Put at the Bottom of a Raised Bed?
If your bed is deep, consider layering sticks, leaves, or other coarse organic material at the bottom to save on soil. Otherwise, line the bottom with cardboard or newspaper to suppress weeds, then fill with your soil mix.
Whether you’re planting herbs, root veggies, or a salad garden, starting with the right soil—and the right amount—sets you up for success.
Catherine Boeckmann loves nature, stargazing, and gardening so it’s not surprising that she and The Old Farmer’s Almanac found each other. She leads digital content for the Almanac website, and is also a certified master gardener in the state of Indiana. Read More from Catherine Boeckmann
A mix that is 40% top soil, 40% Compost and 20% course sand is really great. But this mix is very "fluffy" (try lifting a 1cuft bag of sand and a 1 cuft bag of compost to notice the difference in density). Using the LxWxH calculation (4x8x2) bed requires 2.37 cubic yards of the mix. I install many beds. If I ordered this amount of bulk soil or purchased the 87 bags suggested I'd have a significant amount left over. I would reduce it by 15%-25% based on how how much I water-in the soil which adds to the compaction of the compost and topsoil (if I'm a little off I can top off the bed with a few more bags of compost which I prefer over returning 20+ bags). I prefer to not overly water in the soil so that I get more natural compaction and deal with the settling the 2nd year.
The soil calculator uses loose fill volume to help ensure beds start full. Over time, rain and watering cause the soil to settle and compact. Since settling reduces volume, it’s usually best to begin with a full (or slightly overfilled) bed to maintain your desired soil level. That said, some gardeners prefer to start with a little less and treat it as a multi-year project, topping off later as needed. It’s all about personal preference and how you like to manage your beds.
Thanks for the great information, Catherine! Just starting with raised beds this summer (albeit a bit late) and was so happy to see this info from you! Still teaching me great skills all these years later :)
Aw, thank you, Kelli! That means so much—I’m thrilled you’re diving into raised beds this summer! It’s never too late to get growing. Let me know how it goes (and what you’re planting!). Glad to hear from you. :-)
