Soil calculator for Delaware

At 12 inches deep, a 4 x 8 raised bed needs 32 cubic feet of soil. That comes to 1.2 cubic yards, which can catch new bed builders off guard when they planned for just a few bags. Use this calculator for beds, planters, or yard work and choose among the three soil types available. The blend changes the weight: garden soil runs about 2,000 lb per cubic yard, screened topsoil 2,200, and fill dirt 2,400. Select what you intend to order for an accurate ton total.

Three steps for bed math

1. Enter the length, width, and depth of every bed or planter in feet. Multiple-areas mode combines the quantities for all beds.
2. Choose depth by purpose: use 4-6 inches to amend a current bed, 6 inches for a new ground-level bed, or 12 inches in an empty raised planter.
3. To convert cubic feet to cubic yards, divide by 27. For tons, use yards x 1.0 to 1.2 according to the soil selected.

Coverage and soil weights

Choose soil for the work

• For flower beds, vegetable plots, and planters, use compost-blended garden soil that is ready for planting.
• Use screened topsoil on lawns and for final grading. Lawn depths and sample calculations are in the Topsoil Calculator.
• Use fill dirt as the lower layer when filling holes or building up grade, then save growing soil for the surface layer.
• Rather than replacing an entire worn-out bed, work 2-3 inches of garden soil into its upper 6 inches. It takes less material and gives roots an easier transition.

Fill deep raised beds for less

For tall beds, there is no need to use the costlier blend from bottom to top. Beds taller than 18 inches can use fill dirt or coarse organic matter that breaks down in place for the lower third, then 8-12 inches of garden soil at the surface for root growth. Run the calculator twice, once for each layer. Measure the full 12 inches rather than estimating it.

Example: three 4 x 8 beds

At 12 inches deep, a 96-square-foot bed holds 96 cubic feet, which comes to 3.6 cubic yards or around 3.6 tons of garden mix. Buy 4 yards so there is material left over. During the first weeks, the compost in a blended mix may compact by roughly 10%; spread the remaining soil over the beds once that settling occurs.

Improve clay and sand in place

Clay can hold water too long, while sand can shed it quickly and leave plants dry between watering. In Delaware, both can benefit from tilling 2-3 inches of compost-blended garden soil through the top 6 inches and repeating that work for a couple of seasons. This uses a third of the material and labor of replacing the full depth, while roots and worms continue mixing it lower. Consider full-depth replacement only where debris from construction or contamination makes the existing soil unsuitable.

Bulk soil or bagged soil

At 40 lb each, a cubic yard comes to about 36 bags. A raised bed can become a 43-bag job, which means handling 43 bags more than once. Bulk costs less by the cubic foot and arrives in one tip, with free delivery. Bags are useful for topping up one planter. Ask for the pile to be tipped onto a tarp, since soil may stain concrete and the tarp makes cleanup a drag-and-fold job.

Soil math for beds and bags

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