Soil Calculator

How to use this soil calculator

What this calculator does

This calculator estimates the volume of soil required to cover a rectangular space or a separately measured area at a chosen finished depth. It also estimates the material's weight from bulk density, rounds the result up to a purchasable number of bags, and calculates a bulk-volume cost. It is useful for raised beds, lawn topdressing, new planting beds, and filling planters. It does not determine soil quality, compaction behavior, drainage suitability, nutrient needs, or the safe payload of a vehicle; those require product information and site-specific judgment.

When to use it

Use it before requesting a bulk-soil quote, comparing bagged and bulk products, planning delivery access, or checking whether a project fits a material budget. For irregular areas, divide the site into simple shapes, total their areas, and select Known area.

How to calculate

1. Choose U.S. customary or Metric. A system change converts the values already entered rather than merely relabeling them.
2. Select Length × width for a rectangle, or Known area when you already have the combined surface area.
3. Enter the dimensions or area, then enter Soil depth. Use the intended finished layer thickness.
4. Enter Bulk density from the supplier or product data. Density affects weight but not volume.
5. Enter the labeled Bag size and the Price per volume. Results update immediately.
6. Read Volume needed, Area, Weight needed, Whole bags, and Estimated cost. Review the conversion table for ordering units.
7. Use Download Excel to save the current model, or Reset to restore the documented defaults.

Input guide

Measurement system is required and controls all displayed measurement units. Area method is required and determines whether the calculator multiplies Length by Width or uses Known area directly. Length and width accept positive decimal feet in U.S. customary mode or meters in metric mode; 10 ft by 10 ft is a realistic small-bed example. Known area accepts positive square feet or square meters. Do not type unit symbols, commas used as decimal separators, or scientific notation.

Soil depth is required and accepts positive inches or centimeters; 6 in is a common example for a new bed. Increasing depth increases volume, weight, bag count, and cost in direct proportion. Bulk density is required and accepts positive lb/ft³ or kg/m³; the default 75 lb/ft³ is only a planning assumption because moisture and composition can change real density substantially. Bag size is required and accepts positive ft³ or liters; a smaller bag increases the rounded bag count. Price per volume is required, accepts nonnegative U.S. dollars per cubic yard or per cubic meter, and affects only cost. A common mistake is entering a per-bag price into this bulk-price field.

Output guide

Volume needed is the exact geometric volume from area multiplied by depth, displayed in cubic yards or cubic meters. Area is either length multiplied by width or the known area entered. Weight needed is an estimate equal to volume multiplied by bulk density. Whole bags divides volume by bag size and rounds upward; zero is possible only when the entered volume is zero, which this calculator treats as invalid for a real project. Estimated cost multiplies bulk volume by the entered price and can be $0.00 when the price is zero. The summary pills repeat these core outputs, and the conversion table presents the same canonical model in commonly used ordering units.

Worked example

With a 10 ft length, 10 ft width, and 6 in depth, the area is 100 ft² and the depth is 0.5 ft. The required volume is 100 × 0.5 = 50 ft³, or 50 ÷ 27 = 1.85 yd³. At 75 lb/ft³, estimated weight is 50 × 75 = 3,750 lb. With 1.5 ft³ bags, 50 ÷ 1.5 = 33.33, so the purchasable result is 34 bags. At $40 per cubic yard, estimated bulk cost is 1.85185 × $40 = $74.07.

Learn more

The geometric method follows the standard volume relationship described in the NIST explanation of volume units. For soil-specific planning, the USDA Natural Resources Conservation Service soil facts explain why soil composition and pore space matter, while the University of Minnesota raised-bed guide provides practical bed-planning context.