Topsoil Calculator
A topsoil calculator turns length × width × depth into cubic feet, then bags at 0.75 ft³ each. A 15 × 8 ft bed at 6 in needs 60 ft³, or 80 bags.
What your order looks like
One bulk delivery is usually easier than hauling it yourself.
2.22 yd³ · 2.4 tons
30 wheelbarrow trips (2 cu ft each)
4 pickup loads (0.75 ton each)
1 small dump truck load (6 tons each)
5 car trips for 80 bags (700 lb each)
Rules of thumb: A wheelbarrow trip is 2 cubic feet of heavy material, about 200 lb, a load most people can push. A pickup load is 0.75 ton, the payload of a full-size half-ton pickup (1,500 lb). A small single-axle dump truck carries about 6 tons. A car or SUV carries about 700 lb of bags per trip, with the driver aboard.
Topsoil calculator: bags from bed size
A topsoil calculator starts with the volume of the bed: length × width × depth, in feet, gives cubic feet. Divide by the bag size, 0.75 ft³ here, and round up to whole bags. A 15 × 8 ft bed filled 6 inches deep holds 60 ft³ of soil, which is 80 bags.
Bags are sold whole, so the calculator always rounds up. When you tick the waste box it adds 10 percent first and then rounds.
The formula in plain words
Imagine the bed as a shallow box and each bag as a small crate. The question is how many crates fit in the box.
- Depth in feet = inches ÷ 12
- Cubic feet = length × width × depth in feet
- Cubic yards = cubic feet ÷ 27
- Bags = cubic feet ÷ 0.75, rounded up
- Cost = bags × price per bag
Worked examples
- Garden bed, 15 ft × 8 ft, 6 in deep, $4 per bag
- Depth: 6 ÷ 12 = 0.5 ft
- Volume: 15 × 8 × 0.5 = 60 ft³ (2.22 yd³)
- Bags: 60 ÷ 0.75 = 80 bags, which is $320
- With the 10% toggle: 80 × 1.10 = 88 bags, which is $352
- Lawn repair strip, 20 ft × 4 ft, 12 in deep
- Volume: 20 × 4 × 1 = 80 ft³ (2.96 yd³)
- Bags: 80 ÷ 0.75 = 106.7, rounded up to 107 bags
- With waste: 118 bags
In example 2 you are buying 107 bags for almost 3 cubic yards, a job a single bulk delivery could cover. Bulk topsoil is also sold by weight in some regions, and at about 1.1 tons per cubic yard that is roughly 3.3 tons.
Bags needed by bed size
| Bed size | Depth | Cubic feet | Bags (0.75 ft³) | With 10% waste |
|---|---|---|---|---|
| 4 × 4 ft | 6 in | 8 | 11 | 12 |
| 8 × 4 ft | 6 in | 16 | 22 | 24 |
| 10 × 10 ft | 4 in | 33.3 | 45 | 49 |
| 12 × 3 ft | 8 in | 24 | 32 | 36 |
| 15 × 8 ft | 6 in | 60 | 80 | 88 |
How to measure your bed
- Measure the soil surface, not the frame. A raised bed with sloped boards is narrower at the bottom than the top.
- Measure depth after clearing. Pull a ruler out of the existing soil to see how much room is left to fill.
- Curved beds. Average three widths along the bed and treat it as a rectangle.
- Split irregular areas. Break the space into rectangles, run each, and add the bag counts.
- Remember settling. Fresh soil sinks as it is watered. Fill slightly proud of your final height.
Common mistakes
- Using inches for depth in the length formula. Six inches is 0.5 ft. Using 6 gives an answer 12 times too big.
- Assuming every bag is the same. Check the printed volume, because bags run from small to over 1.5 ft³.
- Treating bagged soil like bulk. Bagged topsoil often costs far more per cubic foot, so compare both before buying.
- Skipping the base. Putting new soil over compacted subsoil can leave drainage poor. Loosen the existing surface first.
Bagged versus bulk: a break-even check
A cubic yard is 27 ft³, which is 27 ÷ 0.75 = 36 bags. At the default $4 per bag, a yard of bagged topsoil costs 36 × $4 = $144.
If a supplier quotes bulk topsoil below $144 per cubic yard, bulk is cheaper on material alone. Then add delivery, which is often a flat fee, and compare again. For the 15 × 8 ft bed at 2.22 yd³, a flat delivery fee gets spread over more than two yards, which helps bulk win.
Related calculators
For beds that mix soil and amendments, the garden soil calculator works from the same geometry. The raised bed soil calculator fits framed boxes, and the sand calculator helps if you are blending a lighter mix. To convert a cubic-foot answer into yards for a bulk order, use the cubic yard calculator.
Frequently asked questions
How many bags of topsoil do I need?
Multiply length × width × depth in feet to get cubic feet, then divide by 0.75, the size of a common 40 lb bag. A 15 × 8 ft bed at 6 inches is 60 ft³, which is 80 bags before waste and 88 with the 10% allowance.
What depth of topsoil should I use for a new garden bed?
About 6 inches is typical for a new bed built up from grade. Raised beds may need 8 to 12 inches depending on the frame height. Spreading a thin top-up layer over an existing lawn usually needs far less, around 1 to 2 inches.
Is it cheaper to buy topsoil in bulk or bags?
Bulk, sold by the cubic yard, is almost always cheaper per cubic foot once you need more than a yard or two, but it needs delivery or a truck and a place to dump it. A cubic yard is 27 ft³, which is 36 bags of 0.75 ft³. Bags win for small beds and patch jobs.
How much does a cubic yard of topsoil weigh?
This site uses about 1.1 tons per cubic yard for bulk topsoil. Real weight swings with moisture and organic content, and wet soil is much heavier, so confirm with your supplier before loading a trailer.
Do all bags hold 0.75 cubic feet?
No. This calculator assumes 0.75 ft³ because it is a common 40 lb bag size, but bags range from about 0.5 to 2 cubic feet. Read the volume printed on your bag and scale the result: a 1.5 ft³ bag needs half as many bags.
Estimates only. Verify quantities with your supplier before purchasing.