Soil Calculator

Landscape Agronomy & Soil Volume Mechanics

Determining accurate soil volumes for flower beds, lawn grading, and vegetable gardens requires converting three-dimensional linear dimensions into volumetric cubic units.

Primary Volumetric Soil Equations

• Rectangular Volume: V_cu ft = Length (ft) × Width (ft) × (Depth (in)12)

• Circular Bed Volume: V_cu ft = π × (Diameter2)^2 × (Depth (in)12)

• Total Volume with Compaction: V_total = V_cu ft ×

• Cubic Yards: Cu Yds = V_total27

• 1.5 cu ft Bag Count: Bags = V_total1.5

• Total Weight: Tons = Cu Yds × Density2,000

Common Material Densities

• Screened Topsoil: ≈ 2,200 lbs per cu yd (1.1 tons)

• Raised Bed Garden Mix: ≈ 1,800 lbs per cu yd (0.9 tons)

• Organic Mushroom / Yard Compost: ≈ 1,400 lbs per cu yd (0.7 tons)

• Dense Clay / Unscreened Fill Dirt: ≈ 2,500 lbs per cu yd (1.25 tons)

How to Use This Calculator

Enter your Garden Bed Shape / Layout — choose from Rectangular / Square Bed, Circular / Round Bed, Custom Surface Area (Sq Ft), Bed Length or Diameter (Feet) (e.g. 20 in ft), Bed Width (Feet — for rectangular) (e.g. 10 in ft), Soil Layer Depth (Inches) (e.g. 6 in in), Soil Type & Material Density — choose from Screened Topsoil (2,200 lbs/cu yd), Garden Soil / Raised Bed Mix (1,800 lbs/cu yd), Organic Compost (1,400 lbs/cu yd), Settling & Compaction Allowance (%) (e.g. 15 in %), and Price Per Bulk Cubic Yard () (e.g. 42 in /cu yd). Measure twice before entering dimensions — small measurement errors scale up significantly in material estimates.

The Formula

Conversion factors (to SI base unit or reference unit):

topsoil_screened: 2200

garden_mix: 1800

compost_organic: 1400

clay_dense: 2500

Worked Example

Filling two 10 ft by 10 ft raised garden beds (200 sq ft total) with 6 inches of rich topsoil requires 115 cu ft with settling margin, equaling 4.26 bulk cubic yards (or 77 standard 1.5 cu ft bags).

Understanding Your Result

Soil swell (loose vs. bank): Clay soils expand 25–30% when excavated; sand and gravel 10–15%. Compact fills shrink 10–15% from loose volume. Haul truck capacities: standard dump truck 10–14 cubic yards. Cut-and-fill should be balanced on grading projects to minimize hauling costs. Compaction requirements: structural fills typically require 95% Standard Proctor density — verify with a geotechnical report for load-bearing applications.