Topsoil Calculator
Ordering soil is guesswork until you convert your area and depth into cubic yards, which is how bulk suppliers sell it. This topsoil calculator takes your length, width, and target depth, then converts the volume into cubic yards, tons, pounds, and 40-lb bag equivalents. It also accounts for three common soil types, because screened topsoil, garden mix, and fill dirt each weigh differently per yard.
Longest side of the bed or area to fill.
Shortest side of the bed or area to fill.
Target settled depth. Garden beds: 6 in; raised beds: 8–12 in.
Bulk density differs by soil type and moisture.
Topsoil needed
3.7yd³
- Weight
- 4.44ton
- Weight
- 8,889lb
- 40-lb bagsRounded up — bulk delivery is cheaper beyond ~1 yd³.
- 223
How it was calculated
- Area = 20 ft × 10 ft = 200.0 ft²
- Volume = 200.0 ft² × 0.500 ft = 100.00 ft³
- Cubic yards = 100.00 ÷ 27 = 3.70 yd³
- Weight = 3.70 yd³ × 1.2 tons/yd³ = 4.44 tons
How it works
Topsoil is sold by the cubic yard — a 3 ft × 3 ft × 3 ft cube — so the core math is a volume conversion: length × width × depth, all in feet, divided by 27.
Weight comes from multiplying cubic yards by the soil type’s bulk density. Screened topsoil runs about 1.2 tons per yard, garden mix is lighter at 1.1, and compacted fill dirt is heaviest at 1.4.
Bag equivalents simply convert total pounds into 40-lb bags and round up, since you can’t buy a fraction of a bag. Because a single cubic yard weighs over a ton, bagged soil only makes sense for small beds; anything above roughly one yard is far cheaper as a bulk delivery.
The depth you enter should be your target settled depth. Loose soil fluffs up when dumped and compacts as it settles, so the calculator’s 10% extra warning guards against coming up short.
Worked examples
Vegetable garden bed
A 20 ft × 10 ft garden bed at 6 in (0.5 ft) deep: area = 200 ft², volume = 100 ft³ = 3.70 yd³. With screened topsoil at 1.2 tons/yd³ that is 4.44 tons (8,889 lb), or 223 forty-pound bags rounded up.
Backyard leveling with fill dirt
A 30 ft × 12 ft area needing 12 in (1 ft) of fill: area = 360 ft², volume = 360 ft³ = 13.33 yd³. Fill dirt at 1.4 tons/yd³ weighs 18.67 tons (37,333 lb) — a job for a dump truck, not bags.
How to measure
- Measure the longest and shortest sides of the area with a tape, walking the perimeter twice for large yards.
- For irregular beds, sketch the shape on paper and break it into rectangles; sum the rectangles for total area.
- Set your target depth with a ruler or a notched stick — push it into loose soil and read the settled depth, not the fluffy top.
- Subtract anything that displaces soil: existing root balls, buried rocks, or the footprint of raised-bed walls.
- If part of the area is already partially filled, measure the depth you still need, not the total bed height.
- Re-check depth in at least four spots per bed; dips and mounds are the biggest cause of under-ordering.
Assumptions & limitations
Planning estimate
- Bulk densities (1.2 / 1.1 / 1.4 tons per yd³) are industry rule-of-thumb averages; wet soil can weigh 10–25% more.
- The volume assumes a rectangular prism — irregular areas measured by splitting into rectangles stay close, but curved beds are estimates.
- Results are planning estimates for ordering, not engineered fill quantities; structural fills may need compaction specifications from a geotechnical professional.
- Bag counts assume the stated soil type is representative of bagged products, which vary by brand and moisture.
Frequently asked questions
Multiply length × width × depth in feet, then divide by 27. A typical 4 ft × 8 ft raised bed filled 12 in deep needs 32 ft³ ÷ 27 = 1.19 yd³. For most home beds the answer lands between half a yard and two yards, which is exactly the range where bulk delivery beats bagged soil on price.
A cubic yard is a fixed volume, but soil density varies. Screened topsoil averages about 1.2 tons per yard, garden mix with compost is lighter at roughly 1.1, and dense fill dirt runs about 1.4. Wet soil after rain can be heavier still, which is why the calculator treats density as a disclosed rule of thumb rather than a guarantee.
Yes — plan for about 10% extra. Loose soil is fluffy when delivered and settles noticeably after the first few waterings. It is much easier to spread a small leftover pile around the yard than to pay a second delivery fee for half a yard.
Bags make sense below roughly one cubic yard — a car trunk handles that easily. Above that, the bag count climbs into the dozens and the cost per yard is typically double or triple the bulk price, so a bulk delivery or a pickup-truck load from a landscape yard wins.
Not for planting. Fill dirt is subsoil with little organic matter and poor structure for roots; it is meant for raising grades and filling holes. Use screened topsoil or garden mix wherever plants will grow, and reserve fill dirt for the bottom of deep beds or non-planted areas.
Six inches of quality topsoil over native ground is the common minimum, and 10–12 inches gives roots real room in a raised bed. Shallower than 4 inches and plants compete with the compacted native soil underneath; deeper than 12 inches mostly adds cost without much benefit for annual vegetables.