Soil calculator for Minnesota

A 4 x 8 raised bed filled to 12 inches takes 32 cubic feet of soil, or 1.2 cubic yards. That is often more soil than a first bed builder expects when planning for a few bags. Use this calculator for beds, planters, and yard jobs in the three soil types available. Soil weight changes by blend: garden soil runs about 2,000 lb per cubic yard, screened topsoil 2,200, and fill dirt 2,400. Choose the material for your order to get the correct ton total.

Three steps for bed math

1. Use feet for each bed or planter measurement. Multiple-areas mode adds the beds into one total.
2. Choose depth by use: improve established beds with 4-6 inches, use 6 inches for a new ground-level bed, and allow 12 inches for an empty raised planter.
3. Divide cubic feet by 27 to get cubic yards. For tons, multiply yards x 1.0 to 1.2 based on the soil type.

Coverage and weights

Choose soil for the job

• For vegetable beds, flowers, and planters, use garden soil mixed with compost for planting.
• Screened topsoil works for lawn areas and finish grading. Find lawn-depth guidance and examples in the Topsoil Calculator.
• Put fill dirt below for grade changes and filled holes, then use good soil at the surface growing layer.
• When native ground is worn out, work 2-3 inches of garden soil through the upper 6 inches instead of swapping out the entire bed. It costs less, and plants adjust more easily.

Lower-cost ways to fill raised beds

A deep bed does not need garden blend from bottom to top. For beds taller than 18 inches, use a lower third of less costly material, either fill dirt or coarse organic matter that composts in place. Keep 8-12 inches of garden soil at the top for roots. Run the calculator twice for the two layers. In Minnesota, measure the full 12 inches instead of estimating before ordering for raised beds.

Example: three 4 x 8 beds

A bed measuring 96 square feet and filled 12 inches deep holds 96 cubic feet. That works out to 3.6 cubic yards, or 3.6 tons, of garden soil. Order 4 yards. In the first weeks, blended soil settles roughly 10% as its compost portion compacts. Use the extra material to refill the beds after that initial settling.

Improve clay and sand in place

Clay ground can stay wet, while sand lets water pass through before plants can use it. In either case, mix 2-3 inches of garden soil containing compost into the upper 6 inches and do it again for a couple of seasons. That uses a third of the material and lifting required to replace the full depth. Roots and worms gradually carry the improvement farther into the soil. Replace the full depth only when construction debris or contamination makes the native ground unsuitable.

Bulk soil or bagged soil

One cubic yard is about 36 bags at 40 lb. A raised bed can already mean 43 bags, and moving 43 bags twice is a lot of loading. Bulk soil has a lower cost per cubic foot and comes in one tipped load. Free delivery means no truck fee to make up. Bags make sense for topping off one planter. Have the load placed on a tarp because soil can mark concrete, then fold and pull the tarp away for cleanup.

Soil amounts for beds and bags

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