Soil calculator guide

A soil calculation starts the same way as any other landscaping material: area in square feet times depth, converted to cubic yards or cubic feet. What makes soil specific is choosing the right type for the job, since garden soil, topsoil, and compost are often confused even though they serve different purposes and are priced and sold differently by most suppliers.

Garden soil versus topsoil versus compost

Topsoil is closer to natural mineral soil, sometimes screened to remove large rocks and debris, and is generally used to build up grade, fill low spots, or serve as a base layer before something else is planted. Garden soil is a blend, often topsoil enriched with compost or other organic matter, formulated to be planted into directly, which is why raised beds and new flower or vegetable beds typically call for garden soil rather than plain topsoil. Compost is different again: it is an amendment, usually worked into existing soil or applied as a thin top dressing rather than used as a bulk fill material on its own.

Typical depths for soil projects

Filling a raised bed usually calls for 8 to 12 inches of garden soil, matching the depth of the bed frame itself. Leveling a low spot in a lawn or preparing ground before seeding typically uses 2 to 4 inches of topsoil. A vegetable bed dug into existing ground might only need 4 to 6 inches of garden soil worked into the top of the native soil rather than a full depth replacement. Because these depths vary so much by project, checking the specific depth for your situation before calculating volume matters more for soil than for a more uniform material like mulch.

Worked example

A raised bed frame measuring 8 feet by 4 feet, filled 10 inches deep, is 32 square feet of area. At 10 inches deep, one cubic yard covers about 32 square feet, so this bed needs almost exactly one cubic yard of garden soil, and most gardeners round up slightly to account for settling once the soil is watered in and beds down over the following weeks.

Weight matters more for soil than you might expect

A cubic yard of topsoil or garden soil weighs roughly a ton, sometimes more when the soil is moist, which is worth knowing before ordering a delivery to a wooden deck, a trailer with a load limit, or any surface with a weight restriction. Moisture content changes this figure meaningfully: soil delivered right after rain can weigh noticeably more than the same soil delivered dry, so treat weight estimates as a starting point rather than an exact delivered figure.

Calculate your own numbers

The gravel and mulch calculator includes both topsoil and garden soil blend as separate material choices, each with its own density, so you can enter your bed dimensions and depth once and get cubic yards, cubic feet, and an estimated weight specific to the soil type you have chosen rather than a generic average.

Soil Coverage by Depth

Use this quick reference to estimate how much topsoil or garden soil one cubic yard covers at common project depths.

Depth	1 cu yd covers	Typical use
2 inches	162 sq ft	Lawn topsoil
3 inches	108 sq ft	Top dressing
4 inches	81 sq ft	Low spots
6 inches	54 sq ft	New bed
8 inches	40.5 sq ft	Raised bed
10 inches	32.4 sq ft	Deep bed
12 inches	27 sq ft	Full bed

Divide your project square feet by the coverage shown to estimate cubic yards, then round up for settling and uneven ground.