Topsoil Calculator
Work out how much topsoil your project needs: in cubic yards, bags and tons.
Topsoil is sold by the cubic yard in bulk and by the bag for small jobs, and both are heavy. Order too little and you pay a second delivery fee; order too much and you own a muddy pile for a year. This calculator turns a length, a width and a depth into cubic yards, bags and an approximate weight, so you can order once and order right.
Measure the area first, then decide the depth: 2 in to top up an existing bed, 4 to 6 in for a new bed on poor ground, 6 to 8 in over compacted subsoil. If the bed itself is raised, the Raised Bed Soil Calculator works out the fill mix instead.
How this is worked out
Cubic feet = length (ft) x width (ft) x depth (in) / 12. Cubic yards = cubic feet / 27. Bags = cubic feet / bag size, rounded up. Weight uses the common planning figure of about 2,200 lb per cubic yard for screened topsoil; wet soil can weigh 2,400 lb or more, dry soil nearer 2,000 lb.
Assumptions:
- The area is a rectangle. For an L-shaped bed, split it into two rectangles and add the results.
- Depth is the settled depth. Loose topsoil compacts roughly 10-20% in the first weeks.
- Bag sizes are as printed; a 40 lb bag is about 0.6 to 0.75 cu ft depending on moisture.
Worked examples
1. A 12 x 4 ft raised bed, 4 in of topsoil on top. 48 sq ft x 4 / 12 = 16 cu ft = 0.59 cubic yards, or 11 bags of 1.5 cu ft. Bags are the sensible buy here.
2. Levelling a 20 x 15 ft lawn area at 2 in. 300 sq ft x 2 / 12 = 50 cu ft = 1.85 cubic yards, about 2 tons. Bulk delivery wins.
3. A new 30 x 10 ft border at 6 in over subsoil. 300 x 6 / 12 = 150 cu ft = 5.6 cubic yards. Order 6 yards and spread the spare on thin spots.
How much one cubic yard covers
| Depth | Sq ft per cubic yard | Weight per 100 sq ft |
|---|---|---|
| 2 in | 162 sq ft | about 1,360 lb |
| 4 in | 81 sq ft | about 2,720 lb |
| 6 in | 54 sq ft | about 4,070 lb |
| 8 in | 40 sq ft | about 5,430 lb |
That weight matters: a cubic yard is more than a ton. A standard pickup bed carries about half a yard safely, which is why delivery exists.
Common mistakes
- Measuring the outline, not the area. Paths, stepping stones and the compost bin footprint do not need soil. Subtract them or the order grows.
- Forgetting settlement. A bed filled level today is an inch low in a month. The 10-20% settling allowance is not supplier padding.
- Putting topsoil straight on compacted subsoil. Fork or till the surface first so roots and water cross the boundary; a clean layer on a pan behaves like a bathtub.
- Ordering bags for a yard-plus job. Past about 27 cu ft, bags cost several times the bulk price and fill your car with plastic.
Putting the result to work
Get the delivery dropped as close to the bed as the truck can reach; every wheelbarrow yard is about 3 cubic feet, so a 5 yard order is roughly 45 barrow loads. Spread in two passes with a rain gap between them if the ground is soft. For the beds themselves, the Garden Bed Calculator works out area and edging, and the Mulch Calculator finishes the surface once the soil is in.
How much topsoil do I need?
- Measure the bed: length x width in feet = area in square feet.
- Pick a depth: 2 in to top up, 4 to 6 in for a new bed, 6 to 8 in over compacted subsoil.
- Cubic feet = area x depth in inches / 12. Cubic yards = cubic feet / 27.
- Add 10-20% for settling if the soil will be rained on before planting.
- Choose bulk over bags once the job passes about 1 cubic yard.
How deep should topsoil be?
Two inches refreshes an existing bed. New beds on decent ground do well with 4 to 6 inches. Over compacted subsoil or rubble, 6 to 8 inches gives roots a real layer to grow in. Deeper than that, use the Raised Bed Soil Calculator and build up with a proper soil mix instead of plain topsoil.
How much does a cubic yard of topsoil weigh?
About 2,200 lb (just over a ton) for typical screened topsoil. Wet soil can reach 2,400 to 2,700 lb per yard, dry soil can be nearer 2,000 lb. That is why a pickup truck is usually limited to half a yard per trip.
Is bulk or bagged topsoil cheaper?
Bulk, by a wide margin, once you need a cubic yard or more. A cubic yard is 27 one-cubic-foot bags; at garden centre prices that is often three to five times the delivered bulk price. For a wheelbarrow-sized top-up, bags win on convenience.
How many bags are in a cubic yard?
Twenty-seven 1 cu ft bags, eighteen 1.5 cu ft bags, or about forty 40 lb bags (a 40 lb bag holds roughly 0.6 to 0.75 cu ft depending on moisture). Always check the volume printed on the bag, not just the weight.
Should I mix anything into topsoil?
Plain topsoil is low in organic matter. For vegetable beds, blend in 20-30% compost by volume, which is what the Raised Bed Soil Calculator assumes. For lawns and general levelling, topsoil alone is fine.
Volume formulas are standard geometry. Weight planning figure (about 2,200 lb per cubic yard) follows common landscape supply guidance; actual weight varies with moisture and soil type.
