Raised garden beds are ideal for vegetable gardens. With a raised garden bed you can control the quality of soil in your vegetable garden. For my raised garden bed, I usually create a blend of nutrient rich soil. I do this by mixing topsoil, compost and potting mix for my raised garden bed. Below, I built a soil calculator to help you compute how much topsoil vs. compost is needed in your raised garden bed. The soil calculator will calculate the total number of soil needed for your raised garden bed and then it will break it down by how much topsoil, how much compost and how much potting mix is needed to fill your raised garden bed. The soil calculator below will also calculate the number of bags of topsoil, compost and potting mix needed for your raised garden bed. I’ve made it easy for you. Just fill in the measurements of your raised garden bed and the soil calculator will do the math for you!
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How to Calculate Soil Needed for Raised Garden Bed?
You need the dimensions of your raised garden bed to calculate how much soil is needed to fill your raised garden bed. Measure the length in feet, measure the width in feet and measure the height in inches (important: inches not feet for height of raised garden bed), then simply multiply the LENGTH (ft) x WIDTH (ft) x HEIGHT (inches) of the raised garden bed to get the total cubic feet of soil needed to fill your raised garden bed.
How Many Bags of Soil Do You Need for a 4 x 8 raised garden bed? (Total Soil)
I have a 4×8 raised garden bed. For a 4×8 raised garden bed that is 8 inches high, you will need 21.44 cubic feet of soil or 15 bags of soil. 15 bags of soil is needed if each bag of soil contains 1.5 cubic feet of soil. This figure is for the total soil needed to fill your raised garden bed. But if you are making a blend of topsoil, compost and potting mix, this total number is not the right number to use, it has to be broken down into 3 parts.
Buy My Raised Garden Bed: Greenes Fence Raised Garden Bed 4×8
Soil vs Compost for Raised Garden Bed
For nutrient rich soil, I suggest making a blend of topsoil, compost and potting mix. How much soil do you need versus compost for raised garden beds? For my soil blend, I use the ratio of 60% topsoil, 30% compost and 10% potting mix. That’s the blend I use for my raised garden bed.
How Many Bags of Compost Do You Need for a 4 x 8 raised garden bed?
You will need 30% compost to make the soil blend for your 4×8 raised garden bed. That means for a 4×8 raised garden bed, you will need 8.57 cubic feet of compost. If your compost comes in 1 cubic feet bags, then you will need 9 bags of compost. I usually buy Black Cow compost, the 50 lb. bag is roughly 1 cubic feet. So for my 4×8 raised garden bed, I fill it with 9 bags of the Black Cow compost.
Buy It: Black Cow Compost
How Many Bags of Topsoil Do You Need for a 4 x 8 raised garden bed?
You will need 60% topsoil to make your soil blend for your 4×8 raised garden bed. That means for a 4×8 raised garden bed, you will need 12.86 cubic feet of compost. If the topsoil comes in 0.75 cubic feet per bag, then you will need 17 bags of topsoil.
How Many Bags of Potting Mix Do You Need for a 4 x 8 raised garden bed?
You will need 10% potting mix to make your soil blend for your 4×8 raised garden bed,. That means for a 4×8 raised garden bed, you will need 2.14 cubic feet of potting mix. If the potting mix comes in 1 cubic feet per bag, then you will need 2 bags of potting mix. I usually use the Miracle-Gro Potting Mix.
Buy It: Miracle-Gro Potting Mix
Raised Garden Bed Soil Calculator
Use the Raised Garden Bed Soil Calculator below to determine the number of bags of topsoil, compost and potting mix needed to fill your raised garden bed. You will need the dimensions of your raised garden bed and you need to know the size of the bag of compost, topsoil and potting mix. Bags of soil, compost and potting mix are commonly sold in 0.75 cubic feet bags, 1 cubic feet bags or 1.5 cubic feet bags, check how many cubic feet comes in the bag you are buying so you can accurately input it into the soil calculator.