Raised Garden Bed Soil Calculator
Estimate the total volume of soil in cubic yards and cubic feet, along with the retail bag count, needed to fill a raised garden bed planter box.
Calculation Results
Total volume of soil needed to fill the raised bed in cubic feet.
Total volume of soil needed to fill the raised bed in cubic yards.
Estimated count of retail soil bags required.
How This Calculator Works
To use the Raised Garden Bed Soil Calculator:
- Enter the inside length and width of the raised bed planter box.
- Enter the vertical height/depth of the planter box.
- Choose the soil bag size you plan to purchase (1.5 cubic foot bags are the standard size in garden centers).
- The calculator immediately determines the total required soil volume and the number of bags to buy.
Formula & Calculations
Raised garden bed volume is calculated using the internal dimensions of the planter box:
Soil Volume (Cubic Feet) = Length × Width × Height
To convert from cubic feet to cubic yards, we divide by 27:
Soil Volume (Cubic Yards) = Soil Volume (Cubic Feet) / 27
Bagged soil is sold in standard volumes (typically 1.5 cubic feet). The bag count is calculated by dividing total cubic feet by the bag size and rounding up to the nearest whole bag:
Bags Required = ceil(Soil Volume in Cubic Feet / Bag Size)
Step-by-Step Calculation Examples
Typical 8x4 Raised Bed
A standard 8ft long by 4ft wide planter box that is 1.5ft deep, using standard 1.5 cu ft soil bags.
- bed_length: 8
- bed_width: 4
- bed_height: 1.5
- bag_size: 1.5
- soil_volume_cu_ft: 48.0 cu ft
- soil_volume_cu_yd: 1.78 cu yd
- bags_needed: 32
Frequently Asked Questions
Do I need to fill the entire raised bed with expensive soil?
For deep beds (over 18 inches), you can fill the bottom 30% with organic logs, branches, leaves, and cardboard (a method called Hugelkultur), and top it with 12 inches of high-quality soil. This saves money and improves drainage.
How deep should soil be for raised bed vegetables?
Most vegetables require at least 8 to 12 inches of soil depth. Large root vegetables (like carrots, parsnips, and daikon) and heavy-feeding tomatoes do best with 12 to 18 inches of soil.
How many bags of soil fill a standard 8x4 raised bed?
A standard 8x4 raised bed that is 1 foot deep requires 32 cubic feet of soil. If using 1.5 cubic foot bags, you will need 22 bags. If the bed is 1.5 feet deep, it requires 48 cubic feet (32 bags of 1.5 cu ft).
Is it cheaper to buy soil in bulk or in bags?
If you need more than 1 cubic yard (27 cubic feet) of soil, buying bulk soil from a local nursery is usually much cheaper than buying individual plastic bags at a home center, even factoring in delivery fees.
Should I put landscape fabric at the bottom of a raised bed?
If the raised bed is sitting on turf, laying cardboard at the bottom is preferred over fabric. Cardboard will suppress grass and weeds, but decompose over time to allow deep earthworms and roots to travel between soil layers.