The square footage calculator and the topsoil calculator answer two halves of the same landscaping question: how big is the bed, and how much topsoil will that bed take? The square footage calculator measures the area of a rectangular, circular, or triangular space. The topsoil calculator starts from that area, applies a depth in inches, a waste allowance, a bulk density, and a package weight, and reports volume in cubic yards, scenario weight in tons, and whole bags to order. If you already know the area, skip straight to the topsoil calculator; if you only have tape measurements, the square footage calculator supplies the missing input.
What each calculator does
The square footage calculator computes area from entered dimensions: length times width for rectangles, π times the radius squared for circles, and base times height divided by 2 for triangles, with dimensions converted to a common unit first. It also shows perimeter for rectangles and an optional cost per square foot. It deliberately does not infer irregular boundaries, excluded areas, measurement tolerance, or installation waste — the article recommends breaking complex spaces into measured shapes.
The topsoil calculator computes base volume = area × depth, with depth in inches divided by 12 to reach cubic feet. The entered waste percentage scales that volume, and the adjusted volume is displayed in cubic yards using 1 cubic yard = 27 cubic feet. Scenario weight multiplies the adjusted volume by the entered bulk density in pounds per cubic foot and displays short tons using 2,000 pounds per ton; whole bags are the ceiling of scenario weight divided by the entered package weight. In the worked example, 300 square feet at 6 inches gives 150 cubic feet, or 5.56 cubic yards; at 75 pounds per cubic foot the scenario weight is 11,250 pounds, or 5.63 tons, which is 282 whole 40-pound bags.
Side-by-side
| Topsoil calculator | Square footage calculator | |
|---|---|---|
| Inputs | Area, depth, waste, bulk density, package weight | Dimensions for rectangle, circle, or triangle |
| Primary output | Cubic yards, cubic feet, tons, whole bags | Area (sq ft), perimeter for rectangles, optional cost |
| Formula basis | volume = area × depth ÷ 12; ÷ 27 for cubic yards; density × volume for tons | L×W, πr², or bh/2 after unit conversion |
| Waste handling | Applied once before weight and bag rounding | Not inferred |
| Density | User-supplied; the ton result is conditional on it | Not applicable |
| Typical uses | Buying topsoil for a measured bed or lawn | Measuring beds, rooms, or other regular areas |
| Output precision | Two decimals on volume and tons; whole-bag ceiling | Two decimals on area and perimeter |
When to use which
Use the square footage calculator when your question is “how big is the space”: you have a tape measure and a bed, room, or other surface with a regular shape. Its output feeds not only the topsoil calculator but also the tile, concrete, paint, and mulch calculators, which all take area as an input.
Use the topsoil calculator when your question is “how much topsoil do I need”: you know the area and want volume, scenario weight, and whole bags for the depth you plan to spread. It applies the depth, waste, density, and package weight itself, so you get a purchase count rather than an area. For a bed you have not measured yet, run the square footage calculator first and then carry the area over.
Limits and disclaimer
Both pages are planning tools for DIY estimation, not installed-cost or delivery guarantees. The square footage calculator does not infer waste, irregular boundaries, or measurement tolerance, and the topsoil calculator’s ton and bag results are conditional on the bulk density and package weight you enter — density, moisture, compaction, and package fill vary, so the article advises recording the density basis and rerunning across a plausible range. Zero area or depth can produce zero volume, but density and package weight must remain positive. Treat the result as a starting point and confirm with the supplier’s product data.