Soil calculator for New Mexico

A 4 x 8 raised bed with a 12 inches fill depth takes 32 cubic feet of soil. That works out to 1.2 cubic yards, which can be more material than new bed builders expect when planning for a few bags. Use this calculator for beds, planters, or yard work and select from the three soil types available. Material weight changes by blend: garden soil is about 2,000 lb per cubic yard, screened topsoil is 2,200, and fill dirt is 2,400. Choose the soil you plan to order for an accurate ton total.

Three steps for bed math

1. List the dimensions of every bed or planter in feet. Multiple-areas mode combines the entries as you go.
2. Plan for 4-6 inches when improving an existing bed, 6 inches for a new ground-level bed, or 12 inches in an empty raised planter.
3. Divide cubic feet by 27 for cubic yards. Multiply yards by 1.0 to 1.2 for tons based on the soil selected.

Coverage and weight

Choose soil for the job

• Use compost-blended garden soil for vegetable gardens, flower beds, and planters. It is ready for planting.
• Choose screened topsoil for lawn work and final grade shaping. The Topsoil Calculator includes lawn depth guidance and examples.
• Use fill dirt as the lower layer for hole filling and grade changes, then place growing soil on top.
• Instead of replacing an entire worn bed, work 2-3 inches of garden soil into its upper 6 inches. You use less material, and roots meet a gradual change in soil.

Fill deep raised beds for less

For a bed taller than 18 inches, you do not need planting blend at the full depth. Put fill dirt or coarse organic matter that composts in place in the lower third, then reserve 8-12 inches of garden soil for the root zone. Calculate each layer separately with two quick entries. In New Mexico, measure the full 12 inches rather than estimating, especially where dry ground can make a bed look fuller than it is.

Example: three 4 x 8 beds

At 12 inches deep, Ninety-six square feet of bed space equals 96 cubic feet. That is 3.6 cubic yards, or about 3.6 tons of garden soil. Order 4 yards. Compost in blended soil consolidates during the first weeks, causing roughly 10% settling, so the extra can be used to refill the beds.

Improve clay and sand in place

Clay can hold water too long, while sandy ground can dry out between watering. Address either condition by mixing 2-3 inches of compost-blended garden soil into the upper 6 inches, then repeat over a couple of seasons. This uses a third of the material and lifting compared with replacing soil at full depth. Consider full replacement only when construction debris or contamination makes the native ground unusable.

Bulk soil or bags

One cubic yard is about 36 bags at 40 lb each. A raised bed can already require 43 bags, so buying bulk avoids loading 43 bags twice. Bulk costs less per cubic foot and arrives as one tipped load with free delivery. Bags make sense for topping off a single planter. Have the pile placed on a tarp because soil can stain concrete, and the tarp makes cleanup easier to drag and fold.

Soil amounts for beds and bags

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