How this soil calculator works
Filling a raised bed or garden area comes down to one idea: volume = length × width × depth. Measure how long and how wide your bed is, decide how deep you want the soil to sit, and multiply the three together. The result is a volume, which bulk suppliers quote in cubic yards (US) or cubic meters (metric), and which bagged soil quotes in cubic feet or liters.
The key is keeping units consistent. This tool converts your depth into the same unit as the length and width before multiplying, so a depth entered in inches is turned into feet first (divide by 12), and a depth in centimeters is turned into meters (divide by 100). If you are filling several identical beds, set the number of beds and the volume is multiplied accordingly.
Once it has the volume, the calculator converts between cubic feet, cubic yards, cubic meters and liters (1 cubic yard = 27 cubic feet; 1 cubic foot ≈ 28.3 liters). It then divides the volume by common bag sizes — 1.5 cu ft, 2 cu ft and 40-liter bags — rounding up so you never come up short. Bag sizes vary by brand and region, so always check the label.
Reference note: conversions use 1 cubic yard = 27 cubic feet and 1 cubic foot = 28.3168 liters. Bag sizes vary between brands and countries, so the bag counts are estimates — round up and order a little extra to allow for settling and topping up after the soil compacts.
Frequently asked questions
- How much soil do I need for a raised bed?
- Multiply the bed's length by its width by the depth you want to fill. For example a 4 ft × 8 ft bed filled 12 inches deep needs 4 × 8 × 1 = 32 cubic feet of soil, which is about 1.19 cubic yards. This calculator does the conversions and also estimates how many bags you will need.
- How do I calculate soil volume?
- Soil volume is length × width × depth. Keep all three measurements in the same unit first — convert a depth in inches to feet by dividing by 12, or a depth in centimeters to meters by dividing by 100. The calculator handles that and reports the volume in cubic feet, cubic yards, cubic meters and liters.
- How many bags of soil do I need?
- Divide the total volume by the size of one bag and round up. A 1.5 cu ft bag holds about 42.5 liters and a 2 cu ft bag about 56.6 liters, while a 40-liter bag is about 1.41 cu ft. Bag sizes vary by brand and region, so check the label and round up to avoid coming up short.
- How deep should garden soil be?
- Most raised beds are filled 8 to 12 inches (about 20 to 30 cm) deep, which suits most vegetables and flowers. Deep-rooted crops such as carrots, parsnips or tomatoes prefer 18 inches (about 45 cm) or more. Deeper beds need more soil, so depth has a big effect on the total volume.
- How many cubic feet are in a cubic yard?
- There are 27 cubic feet in one cubic yard, because a cubic yard is 3 ft × 3 ft × 3 ft. To convert cubic feet to cubic yards, divide by 27. Bulk soil is usually sold by the cubic yard, while bagged soil is sold in cubic feet or liters.
- What is the difference between topsoil, garden soil and compost?
- Topsoil is the basic upper layer of earth used to fill volume and level ground. Garden soil is topsoil blended with organic matter and nutrients for planting. Compost is decomposed organic material used to enrich and lighten soil rather than fill a whole bed alone. A common raised-bed mix is roughly topsoil, compost and a drainage material such as coarse sand or perlite.