Raised Bed Soil Calculator
Calculate how many bags of soil you need for your raised garden bed.
Use decimals when needed. This estimate updates live and is safe to tweak before you buy materials.
Raised Bed Soil Buying Guide
This guide helps you turn your raised bed soil calculator result into a cleaner purchase plan. Use it when you want fewer return trips, better waste assumptions, and a more realistic cart.
Step 1: Calculate the internal volume
Measure the length, width, and depth of your raised bed in inches, multiply them together, and divide by 1728 to find the exact cubic feet needed.
Step 2: Never use straight topsoil
Topsoil is too dense for raised beds and will turn to concrete. Use a 'Mel's Mix' ratio: 1/3 compost, 1/3 peat moss or coco coir, and 1/3 vermiculite.
Step 3: Fill the bottom with organic matter
If the bed is deeper than 12 inches, fill the bottom half with old logs, branches, and leaves (Hugelkultur). This saves money on expensive bagged soil.
Recommended for this job
Commonly paired tools and accessories
These are the practical extras people often forget until the last minute, especially when turning a rough estimate into a real purchase list.
Raised bed kitWhy this helps: Common add-on that reduces last-minute store runs once the estimate is final.
Organic potting soilWhy this helps: Common add-on that reduces last-minute store runs once the estimate is final.
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Raised bed cost planning rule of thumb
Buying individual bags of premium raised bed soil is very expensive. For multiple beds, have a local nursery deliver a blended 'garden mix' in bulk.
Understanding the Math
Formula: The basic formula for Raised Bed Soil Calculator typically involves calculating the total area or volume (Length × Width × Depth) and dividing by the coverage of a single unit or package, then adding a waste factor (usually 10%).
Example: For example, if you have a 10x10 area and your material covers 10 square feet per unit, you need 10 units. With a 10% waste factor, you should purchase 11 units to ensure you don't run short.
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Raised Bed Soil Calculator FAQ
Should I measure the inside or outside of the bed?
Always measure the interior dimensions. Measuring the outside includes the thickness of the wood or metal, which can cause you to over-calculate and buy too much soil.
Do I need to account for settling?
Yes! Soil and compost usually settle by 5-10% after the first heavy watering. It is highly recommended to buy a little extra to top off the bed.