A Soil Calculator for Raised Beds and Containers

My Garden Life
May 4, 2022
Table of Contents
A soil calculator for raised beds and potted plants can help you avoid frustrating mistakes when setting up your beds or containers. Have you ever gone to the garden center and guessed at how much potting soil or raised bed soil to buy? If so, you likely brought home too little or too much.
The good news is that you don’t need to be a math whiz to use a soil calculator formula and ensure that you get the right amount. We’ve answered some common soil volume questions here and provided the tools necessary for you to do your own calculations. We’ve also found a great online calculator you can use if you prefer.

Soil Calculator – How much soil do I need?

man scooping potting soil from a wheelbarrow and using it to fill two large pots
The calculations provided here will allow you to buy the right amounts to fill your containers or raised beds, but how much it takes to fill them initially is not the only factor to consider. High-quality potting and raised bed mixes are loamy, meaning they are aerated and will pack down to some degree with watering.
As you make your determinations on how much soil you’ll need using the information we’ve provided, err just a bit on the high side so that you’ll have a little left over to add after your soil has settled. Adding about 15 percent to your final calculations should provide you with an adequate buffer.

How much soil do I need for a raised bed?

woman dumping a wheelbarrow load of garden soil into a newly built raised garden bed
Most raised beds are square or rectangular in shape, which makes it easy to calculate how much soil is needed to initially fill them. Here’s the formula if you’d like to do it yourself:

How much soil for raised bed = length X width X depth

So, if your bed is 10 feet long, 6 feet wide, and two feet high, 10 X 6 X 2 = 120 cubic feet of soil. Larger bags of potting soil are often labeled according to cubic feet with most being offered in 2 cubic foot bags. If you’re filling a 120 cubic foot raised bed, you’ll need 60 bags (4.4 cubic yards) of soil.
That’s a lot of bags! It may be easier and cheaper to buy in bulk. Local landscaping supply stores sell by the cubic yard and many deliver if you don’t have a truck.

How much potting soil do I need?

lots of large terra cotta pots filled with a colorful variety of flowering plant combinations
If you’re filling round pots the calculations necessary to answer this question can be a bit involved, so we’ll avoid them and give you direct answers. Based on their top diameters, here are the soil amounts required to fill the most common sizes of round pots:
  • 8 inch (20 centimeter) – 1 gallon (4 quarts or 3.8 liters) – 0.15 cubic foot
  • 10 inch (25 centimeter) – 3 gallons (12 quarts or 11 liters) – 0.46 cubic foot
  • 12 inch (30 centimeter) – 5 gallons (20 quarts or 19 liters) – 0.77 cubic foot
  • 14 inch (36 centimeter) – 7 gallons (28 quarts or 26.5 liters) – 1 cubic foot
  • 16 inch (41 centimeter) – 10 gallons (40 quarts or 38 liters) – 1.5 cubic feet
  • 20 inch (51 centimeter) – 17 gallons (68 quarts or 64 liters) – 2.3 cubic feet
  • 24 inch (61 centimeter) – 25 gallons (100 quarts or 95 liters) – 3.3 cubic feet

How about an online garden soil calculator for raised beds and containers?

woman using a soil calculation app on her smart phone
If you really hate math, don’t worry. You can use an online tool to automatically calculate how much soil you need. You simply enter the length, width, and depth measurements for square or rectangular raised beds or containers, select how you want the results displayed (cubic feet, cubic yards, centimeters, or liters), and click a button.
Most square and rectangular containers taper inward toward the bottom so the calculation result using this tool will be a bit high, but remember that you’ll need some extra soil to account for compression after potting and watering.

The best soil for pots and raised beds

gloved hands putting potting mix in a small terra cotta pot to plant a primula flower
Whether plants are in containers or raised beds, their health will be affected by the quality of soil you use. If you’re unsure about which soil mix will produce the best results for your specific application, you’re in luck. We have tips that will help you make the right soil selection. And, if you’re looking for the right location for raised beds, make sure you select a spot that gets enough sun by measuring the sunlight in your landscape.
raised garden bed made from wood planks and filled with vegetable plants and marigolds

20 Comments

  1. Jacqui

    If I am buying a triple mix for my new elevated garden bed, how much do I need for a 43 long x 17 wide x 10 deep container? Do you have a favorite triple mix?

    Reply
    • My Garden Life

      Hi Jacqui,
      You’ll need from 87 to 109 quarts of soil (3.5 to 4 cubic feet) depending on how deep you want to fill the container. Keep in mind that you’ll want to leave a couple of inches between the soil line and the rim of the container to leave space for watering and to avoid washing the soil out of the container.

      There are many quality, pre-mixed, general-purpose soils on the market to eliminate the guesswork. Which you choose will depend on what is available at your garden center and what you plan on growing in your container. Look for bagged soils that are blended specifically for what you are trying to grow (for example, flowers vs. vegetables). If you want to mix your own soil for general purpose growing, a very basic blend would be 60% soil (top soil or garden soil), 30% compost or peat, and 10% perlite, vermiculite or sand.

      Reply
  2. Rick Rice

    I am using 40 gal containers how much soil do I need ??

    Reply
    • My Garden Life

      Hi Rick,
      For each 40 gallon container you will need approximately 160 quarts (152 liters) or 6 cubic feet of soil to fill.

      Reply
  3. Rachel

    How much soil would you use for a 5 gallon bucket? Thanks!

    Reply
    • My Garden Life

      Hi Rachel,
      Assuming that your five-gallon bucket measures around 12” in diameter and 15” in height, you will need 5 gallons of soil. That’s the equivalent of 20 quarts (19 liters), or 0.77 cubic foot of soil. We’re providing you with multiple measurement options because, unfortunately, there is no standard measurement for prepackaged, bagged soils. You may find product packages printed with measurements in quarts or cu feet. Hopefully this will help you interpret how much you need for whatever product you are considering.

      Reply
  4. Joyce Best

    How much soil do I need for a raised bed, 6 feet long by 2 feet wide and 16 inches tall?

    Reply
    • My Garden Life

      Hi Joyce,
      You’ll need 16 cubic feet of soil to fill your raised garden bed.

      Reply
  5. Jacquelyn Stapleton

    How much soil will I need to fill Mr Stacky vertical planter?

    Reply
    • My Garden Life

      Hi Jacquelyn,
      We’re not familiar with the Mr. Stacky planters and the sizing. We would suggest that you ask the folks at Mr. Stacky directly. Click here to go to their contact page.

      Reply
    • Connie Colestock

      How much soil is needed for a 4 foot long, 30 ” Wide and 8″ deep?
      Thank you

      Reply
      • My Garden Life

        Hi Jacquelyn,
        You will need 7 cubic feet of soil to fill this space. If you plan to use bagged garden soil, and assuming that each bag is around 2 cubic feet (sizes vary but most are close to this size) then 4 bags of soil should be adequate.

        Reply
  6. Maksud

    How much soil do I need for a raised bed, 4 feet long by 3 feet wide and 2 feet height?

    Reply
    • My Garden Life

      Hi Maksud,
      You will need 24 cubic feet of soil to fill your raised garden bed. So that’s around 12 bags if you’re planning to work with bagged soil (assuming each bag is 2 cubic feet), or .9 yards if you’re getting soil in bulk.

      Reply
  7. JD

    How much soil do I need for a rounded pot that is 17x17x19 (in terms of LxWxH) and 54 qt? Thank you

    Reply
    • My Garden Life

      Hi JD,
      If you know that the pot is 54 quart sized, that’s 1.8 cubic feet of soil to fill it. If you’re buying bagged soil it should have a measurement based on either quarts or cubic feet so from that you can determine how many bags you’ll need to fill your pot.

      Reply
  8. anne

    in an 8 inches pot how much soil to put?

    Reply
    • My Garden Life

      Hi Anne,
      As we mention in the article, the amount of soil needed for an 8″ (20cm) pot is: 1 gallon (4 quarts or 3.8 liters) which is also equivalent to 0.15 cubic foot. You will want to reference the weight printed on the bag of potting mix and compare to these numbers to determine which size bag will be appropriate to fill your pot.

      Reply
  9. Roy ans Betty Stevens

    i got a raised bed 1 foot deep 6 foot sq how much soil please

    Reply
    • My Garden Life

      Hi Roy and Betty,
      You will need 36 cubic feet of soil, or 1.3 cubic yards. That is if you were to fill the bed to the top edge, so you may need less soil if you want to leave an inch or so of space to capture water so it doesn’t just spill out over the edges. So, say you decide to just fill it to a depth of 11″ to leave a little space, then you would need 33 cubic feet of soil, or 1.2 cubic yards.

      Reply

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