Topsoil quantity in cubic yards = net area (sq ft) × added depth (in) / 324. A 20 × 10-foot area at a selected 4-inch added depth has 2.469136 cu yd of net geometric volume. Keep that measurement separate from a supplier’s loose-to-installed conversion, any chosen reserve and the final sales increment.
Measure the actual space to fill
- Use inside dimensions for a framed bed. Subtract areas that will not receive soil.
- Calculate added depth, not automatically the total desired soil/rooting depth. Existing usable soil can remain part of the finished profile.
- For a partly filled bed, measure the remaining depth to the intended level.
- Split variable-depth or irregular areas into non-overlapping sections and add unrounded volumes.
- Identify whether the target is loose fill or a firmed/settled layer before applying an order conversion.
Formula and unit conversions
Cu ft = area × depth (in) / 12.
Cu yd = area × depth (in) / 324.
Whole bags = round up (required cu ft / actual labeled cu ft per bag).
One cubic yard equals 27 cubic feet. A rectangular area is length × width; for a true circle, area is π × radius², where radius is half the diameter. Use full precision rather than replacing π with 3.14 before a package threshold.
Net cubic yards by area and selected added depth
| Area | 1 in | 2 in | 4 in | 6 in | 12 in |
|---|---|---|---|---|---|
| 100 sq ft | 0.309 | 0.617 | 1.235 | 1.852 | 3.704 |
| 200 sq ft | 0.617 | 1.235 | 2.469 | 3.704 | 7.407 |
| 500 sq ft | 1.543 | 3.086 | 6.173 | 9.259 | 18.519 |
| 1,000 sq ft | 3.086 | 6.173 | 12.346 | 18.519 | 37.037 |
Rounded display values only. No allowance, density or supplier increment is included. The depths are calculation inputs, not universal gardening or turf recommendations.
Three checked examples
1. A rectangular garden area
A selected 20 × 10-foot area with 4 inches of added material needs 200 × 4 / 12 = 66.666666… cu ft, or 2.469136 cu yd. A hypothetical chosen 10% handling reserve gives 73.333333… cu ft, or 2.716049 cu yd. This percentage is a selected arithmetic example, not a verified settling rate. If the supplier actually sells quarter-yard increments, rounding that selected quantity up gives 2.75 cu yd; otherwise use its actual increment.
2. A 4 × 8-foot framed bed
At a selected 12-inch fill depth, inside volume = 4 × 8 × 12 / 12 = 32 cu ft = 1.185185 cu yd. Stated 1-cu-ft bags: 32. Stated 0.75-cu-ft bags: round up 32 / 0.75 = 43. Stated 1.5-cu-ft bags: 22. Stated 2-cu-ft bags: 16. This estimates total fill space; it does not prescribe filling every raised bed with only topsoil.
3. A circular target
For a true circle with 10-foot diameter, radius is 5 ft. Area = π × 5² = 78.539816 sq ft. At a selected 2-inch added depth, volume = area × 2 / 12 = 13.089969 cu ft, or 0.484814 cu yd. Stated 1.5-cu-ft bags: round up 13.089969… / 1.5 = 9. Do not use the circle formula for a bed that only looks roughly round.
Choose suitable material and depth first
For new lawn establishment, Penn State describes typically at least 4–6 inches of good-quality topsoil at a firmed/settled depth and incorporating part into the subsoil for a gradual transition.1 That is not a loose-order conversion or permission to bury an existing lawn under the same depth. Assess existing soil and final grade; see the lawn-specific guide below.
For raised beds, University of Maryland Extension gives different mixes for compacted ground, existing garden soil and hard surfaces. For non-permeable hard surfaces, it recommends compost and soilless growing mix at 1:1 and permits up to 20% topsoil by volume only in beds at least 16 inches deep.2 The quantity of total bed fill is therefore not necessarily the quantity of topsoil. Calculate each selected ingredient separately and round its actual package/order increment.
UMD also warns that many bagged “organic soil” products contain organic materials rather than mineral topsoil.2 Read ingredients, intended use and volume. Soil testing and site conditions guide amendments; a volume calculator cannot choose them.
From net volume to an order
| Stage | Separate input |
|---|---|
| Net geometry | Area and actual additional depth |
| Volume basis | Loose delivered versus installed/firmed target |
| Conversion | Material-specific loose-to-installed relationship, if needed |
| Reserve | A separately chosen handling allowance, if any |
| Sales rounding | Actual bag volume or supplier bulk increment |
| Weight | Current product density on the matching moisture/volume basis |
Do not automatically add 5–10% for every soil. A conversion, reserve and rounded package surplus are different things. Penn State’s settled-depth statement does not establish a percentage for any supplied product.1
Yards versus US short tons
Short tons = ordered loose yards × matching pounds per loose yard / 2,000. If a supplier hypothetically quotes 2,400 lb per loose yard and the order is 2.75 loose yards, estimated soil weight is 6,600 lb, or 3.3 short tons. The 2,400 figure is an example input, not a universal topsoil density. Verify weight and vehicle limits separately; bed volume does not establish safe payload.
FAQ
How much does one yard cover?
Geometrically, 324 sq ft at 1 inch, 162 at 2 inches, 81 at 4 inches or 54 at 6 inches, before any material-specific loose-to-installed conversion. Coverage depends on the actual added depth.
Can I convert a 40-lb bag into cubic feet?
Not from weight alone. Use the actual labeled volume/yield or a verified matching density.
Should I round each small bed up?
When the same product serves several beds, add their unrounded volumes and round the final purchase quantity. For different ingredients/products, calculate and round each separately.
Are bags or bulk always cheaper?
Compare current delivered totals for the same suitable product and required quantity, including minimums, fees, taxes and unused surplus. This guide does not establish a universal bulk price advantage.
Related tools and guides
Topsoil volume calculator | Lawn topsoil quantities | Raised-bed fill quantities | Topsoil bags per yard | Topsoil weight guide
Sources
- Penn State Extension: Lawn Establishment (new-lawn firmed/settled topsoil depth and subsoil transition)
- University of Maryland Extension: Soil to Fill Raised Beds (site-specific mixes, hard-surface topsoil limit and bagged organic-soil ingredients)
Once you know your yardage, price it with our topsoil cost guide.