Calculation method
Multiply measured area by depth converted to feet, add the editable allowance, and divide cubic feet by 27 for cubic yards. Round bags up by entered bag volume. Round bulk volume up to the entered order increment; compare whole-bag cost with rounded bulk material plus delivery using quotes for the same material.
Worked example: input to purchase quantity
A 200 ft² area at 6 in depth needs 100 ft³ before allowance and 110 ft³ after 10% extra: 4.074 yd³. At 1.5 ft³ each, buy 74 bags. A 0.5 yd³ ordering increment rounds bulk to 4.5 yd³. At $4 per bag versus $45 per yd³ plus $50 delivery, the examples cost $296 and $252.50 respectively.
Estimate a garden soil layer by volume
This calculator is for topsoil, garden soil, sand or compost spread to a selected depth over a measured area. Choose the material label, then enter its area and depth. The material choice is a label for your worksheet; it does not secretly change the formula or imply that all four materials are interchangeable. A 6 in topsoil layer and a 6 in compost layer occupy the same geometric volume, but they may serve different purposes. Confirm the suitable material and depth from your project plan.
Measure the area that will actually receive the layer. For a rectangle, multiply length by width before entering square feet; for several beds, add their separate areas. Exclude paths, structures and beds using a different material. The calculation assumes one uniform depth. If a bed is deeper at one end or has a raised border, split it into sections or estimate the actual shape rather than averaging away a large difference.
Convert square feet and inches to cubic yards
Volume in cubic feet equals area in square feet times depth in inches divided by 12. Multiply by one plus the chosen handling or settlement percentage. Divide the adjusted cubic feet by 27 to obtain cubic yards. The metric result is displayed in cubic metres; a unit change converts the physical dimensions and package volumes so the estimate remains tied to the same project. The entered extra percentage is a planning assumption, not an automatic claim about soil compression.
With the starting values, 200 ft² at 6 in is 100 ft³, or 3.704 yd³. Ten percent extra makes 110 ft³, or 4.074 yd³. A 1.5 ft³ bag count is 110 ÷ 1.5 = 73.33, rounded up to 74 bags. For a supplier that sells in half-yard steps, enter 13.5 ft³ as the bulk increment; the same requirement rounds up to 4.5 yd³. These ceilings are applied separately because bags and bulk delivery are different purchasing formats.
Compare matching quotes
Enter the current price of one bag, the bulk quote per cubic yard, and any delivery charge. In metric mode the bulk quote is per cubic metre; switching units converts the existing quote to preserve its price per physical volume. With the example prices, 74 × $4 = $296 for bags. Bulk is 4.5 × $45 + $50 = $252.50. Those example inputs do not predict local market prices. Compare screened topsoil with screened topsoil, or the same specified sand with the same sand; bagged potting mix and raw fill soil are not equivalent products simply because both have a volume.
The comparison excludes sales tax, bag transport, unloading, wheelbarrow time, equipment, minimum order fees beyond the entered increment, and other project charges. If the supplier quotes a fixed truckload or a minimum order, adjust the order increment or compare the quote manually. For a small job, a lower material-only bulk rate can be offset by delivery. For a large job, individual bags can involve more packaging and handling. Let actual quotes settle the choice.
Check the material and site
Read the bag's stated cubic volume rather than inferring volume from weight. The same mass of dry sand and damp soil does not occupy a guaranteed equal volume. Ask a bulk seller how volume is measured and whether the delivered material meets the specification. The tool uses volume only; it deliberately does not calculate tons, gravel coverage, mulch depth, soil fertility or nutrient applications. Use an appropriate soil test or product guidance for suitability questions.
Before ordering, check access for a delivery truck, where the pile can be placed, and how the material will reach the beds. Confirm that the intended finished grade will not obstruct drainage or bury structures. The result is an auditable quantity and cost worksheet. It cannot inspect the site, establish soil quality or guarantee the delivered loose volume.
Product and method reference
Reference limits and default yields are identified separately from user-entered values; verify the adopted local code and current product label. Iowa State University Extension soil-volume guidance.
Calculation and editorial review: November 3, 2026. Arithmetic runs in your browser; project inputs are not submitted to TwoCut.