Calculate how much soil or fill dirt you need in cubic yards, cubic feet or tons from bed length, width and depth, plus bag counts and bulk order size.
Soil Formula
Net soil volume is area multiplied by the final fill depth. You may enter an additional purchase allowance; blank means zero. This allowance does not predict actual compaction or settling. For identical beds, total area is one bed area times the whole number of beds.
Volume = Area * Depth * (1 + Waste)
When you already have a volume and want to know how many bags to buy, divide the volume by the size of one bag and round up.
BagsToBuy = ceil(Volume / BagSize)
When you have a fixed volume of soil and want to know how deep it will go over an area, divide the volume by the area.
Depth = Volume / Area
To estimate weight, convert the volume to cubic yards and multiply by the soil density.
Weight = CubicYards * Density
- Volume is the amount of soil, usually in cubic feet or cubic yards.
- Area is the surface you are filling, in square feet.
- Depth is how deep the soil will sit, converted to feet so it matches the area.
- Waste is your extra purchase fraction: divide an entered percentage by 100. Blank means zero; no universal compaction allowance is assumed.
- BagSize is the actual labelled package volume. The explicit default is 2 cubic feet; edit it to the product label, or leave it blank to omit bag counts. Whole bag purchases round upward.
- CubicYards is the volume divided by 27, since 27 cubic feet make one cubic yard.
- Density is measured mass per delivered volume, converted from your chosen unit. When using tons here, one US short ton is exactly 2,000 lb (907.18474 kg), distinct from a metric tonne of 1,000 kg.
Soil needed and known-volume purchase modes apply only your entered allowance, then report volume, bag purchases and a bulk order. The default supplier increment is 0.25 cubic yards: orders round upward, not to the nearest increment. Edit the increment or clear it to use exact volume. Bag cost uses whole bags; bulk cost uses the bulk order quantity. Weight uses planned volume and the entered density (default 1 US ton/yd³), separately from order rounding. Depth mode divides the available volume by total area without an allowance. Mix mode splits a total final volume into user-chosen relative parts; 5:3:2 and 50:30:20 are equivalent. The split is not a recommended soil recipe.
Soil Coverage and Weight Reference
One cubic yard of topsoil covers different areas depending on how deep you spread it. Use this to sanity-check the volume the calculator returns.
| Depth | Area covered by 1 cubic yard |
|---|---|
| 1 inch | 324 sq ft |
| 2 inches | 162 sq ft |
| 3 inches | 108 sq ft |
| 6 inches | 54 sq ft |
| 12 inches | 27 sq ft |
Soil bulk density varies with the material and its moisture and packing state. Enter a supplier measurement; a dry, compacted or wet label does not define a universal density. Until you enter a supplier measurement, weight uses a typical 1 US ton per cubic yard for dry topsoil. The following mass-unit definitions keep US short tons separate from metric tonnes.
| Mass unit | Definition |
|---|---|
| 1 US short ton | 2,000 lb = 907.18474 kg |
| 1 metric tonne | 1,000 kg |
Examples
Example 1. An 8 ft × 4 ft raised bed filled 12 inches deep has a net volume of 32 × 1 = 32 cubic feet. If you enter a 10% purchase allowance, planned volume becomes 35.2 cubic feet = 1.3037 cubic yards. At 2 cubic feet per bag, 17.6 equivalent bags requires 18 whole bags. With an explicitly chosen quarter-yard supplier increment, the bulk order rounds up to 1.5 cubic yards. Bag and bulk costs use those respective purchase quantities. The allowance is an arithmetic assumption, not a measured settling rate.
Example 2. You bought 1 cubic yard of soil and want to spread it over a 150 square foot bed. One cubic yard is 27 cubic feet. The depth is 27 divided by 150, which is 0.18 feet, or about 2.16 inches.
FAQ
How many bags of soil are in a cubic yard? One cubic yard is 27 cubic feet. Divide 27 by the bag size to get the count. That is 36 bags at 0.75 cubic feet, 27 bags at 1 cubic foot, 18 bags at 1.5 cubic feet, or about 14 bags at 2 cubic feet.
How should I choose an extra allowance? Use measurements and supplier or project guidance for uneven ground, handling losses and expected material behavior. Blank means zero; you can enter an allowance when justified. Buying extra does not establish the final compacted depth or mean that all purchased material must be applied.
Should I order bags or bulk soil? Compare actual package and bulk prices, supplier increments, delivery fees, access and handling needs. This tool reports whole bags and a bulk order rounded upward to the entered supplier increment; it does not assume which option costs less. Costs omit tax and delivery. Choose soil suitability and any mix proportions using local soil and plant guidance, such as university extension guidance for raised beds.
