Free Calculator · Published November 2026
Soil Calculator for a Raised Bed
A soil calculator multiplies length by width by depth in feet, then divides by 27. A 4 by 8 foot bed at 12 inches deep is 32 cubic feet, which is 1.185 cubic yards. USDA says agricultural bulk density normally runs from 1.0 to 1.6 grams per cubic centimeter. This page does not turn that range into tons.
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Book a DemoHow a Soil Calculator Gets Yards
Measure the inside of the bed. Depth is the soil you want, not the height of the board if the board stands above the fill. Cubic yards = (length × width × depth in feet) ÷ 27.
1 is an example. Use the cubic feet printed on the bag.
Type a supplier or lab figure. The USDA gram range is not filled in here.
32.000 cubic feet = 1.185 cubic yards.
32.00 bags at 1.00 cubic feet each.
Weight is blank until you type pounds per cubic foot.
All calculations are estimates based on historical information and should be verified by the user.
Important: this is a volume
All calculations are estimates based on historical information and should be verified by the user. This tool is provided as a free service for planning purposes only and is not a substitute for a professional assessment, a supplier quote, or applicable local code requirements.
What the Soil Calculator Is Measuring
The number a yard wants for a raised bed is volume. Weight changes when the mix is wet, when it has compost, and when it settles. This soil calculator keeps those apart. The dirt calculator is the page for topsoil and fill tons. Driveway stone stays on the gravel calculator.
The cubic-yard step
A cubic yard is a cube 3 feet on a side. That cube holds 27 cubic feet. The division by 27 is that definition. It is not a density. A cubic yard calculator does the same division for shapes that are not one rectangle.
Worked example
Length 4 feet. Width 8 feet. Depth 12 inches, which is 1 foot. 4 × 8 × 1 = 32 cubic feet. 32 ÷ 27 = 1.185 cubic yards at three decimals. One-cubic-foot bags, the example size, are 32 bags. Bags marked 2 cubic feet are 16 bags of the same 32.
| Step | Figure |
|---|---|
| Cubic feet | 32 |
| Cubic yards at three decimals | 1.185 |
| Bags at 1 cu ft | 32 |
| Bags at 2 cu ft | 16 |
The USDA figures, left in grams
The NRCS soil-health glossary says the bulk density of agricultural soils normally ranges from 1.0 to 1.6 grams per cubic centimeter. The May 2019 bulk-density guide says an ideal silt loam with 50 percent pore space has a bulk density of 1.33 grams per cubic centimeter. The same guide uses 2.65 grams per cubic centimeter as a rule of thumb for the average bulk density of rock, inside a porosity formula. That rock figure is not bagged mix.
This soil calculator does not multiply 1.33 or 1.6 by a pounds factor. Type pounds per cubic foot only when a bag, a lab, or a supplier gives you that number. Compost-heavy bed mix is often lighter than mineral soil. The guide says soils high in organic matter generally have lower bulk density. It does not print a bag weight.
How should you write the order?
- Inside length, inside width, and soil depth, with the unit on each.
- Cubic feet, then cubic yards as cubic feet divided by 27.
- The bag size you used, copied from the bag, and the bag count.
- Whether weight was left blank.
- If you typed pounds per cubic foot, the source of that figure.
- A note that the dirt-calculator ton chart was not applied.
What stays off this bed
Settling after watering is real, and this page does not invent a percent for it. If you want extra volume, add it yourself and write the percent on the note. The dirt page has its own settling allowances. Do not paste those onto a bagged bed mix without checking the product.
Several beds are several rectangles. Add the cubic feet, then divide once by 27. Do not average the depths first. A landscape bed that is actually sand belongs on the sand calculator. Mulch is a different material on the mulch calculator.
Frequently Asked Questions
How does a soil calculator get cubic yards?
Multiply length in feet by width in feet by depth in feet. Depth in inches is divided by 12 first. Divide the cubic feet by 27. A 4 by 8 foot bed at 12 inches is 32 cubic feet, and 32 divided by 27 is 1.185 cubic yards at three decimals.
Does this soil calculator use the dirt calculator densities?
No. The dirt calculator carries its own tons-per-yard chart for topsoil and fill. This soil calculator stops at cubic yards unless you type a pounds-per-cubic-foot figure. It does not copy that chart.
What bulk density does USDA print for soil?
The North Dakota NRCS glossary says agricultural bulk density normally ranges from 1.0 to 1.6 grams per cubic centimeter. The May 2019 bulk-density guide says an ideal silt loam with 50 percent pore space has a bulk density of 1.33 grams per cubic centimeter. Those figures are not converted to tons on this page.
How many bags does the soil calculator count?
Divide cubic feet by the cubic feet printed on the bag. The box starts at 1, which is an example, not a rule that every bag holds one cubic foot. A 2 cubic foot bag of the same 32 cubic feet is 16 bags.
Save the Soil Calculator Yards on the Job
The cubic yards, the bag size, and a blank weight line belong on the customer record.
Get a Free DemoAll calculations are estimates based on historical information and should be verified by the user. This tool is provided as a free service for planning purposes only and is not a substitute for a professional assessment, a supplier quote, or applicable local code requirements.