Soil Calculator
Work out how much topsoil, potting mix or garden soil a bed or raised planter needs.
Last updated · View algorithm, constants and default inputs (JSON)
About this calculator
Volume = length × width × depth, increased by the entered settling allowance. Bag count uses either volume per bag or estimated weight per bag and rounds up once.
Worked example
calculated with the default values below
Bed length 8 ft · Bed width 4 ft · Depth 12 in · Settling allowance 12 % · Bag size 1.5 cu ft · Price per bag 6 $ · Soil type Topsoil (1.1 tons/cu yd) · Custom density (US short tons/yd³) 1.1 · Bag specification Volume per bag · Weight per bag (lb) 40 · Price per cubic yard 40 $ · Bagged or bulk purchase Whole bags Soil volume 35.8 cu ft · Soil volume 1.33 cu yd · Bags needed 24 · Approximate weight 1.46 tons · Estimated cost 144.00 $ · Bagged purchase cost 144.00 $ · Bulk material cost 53.10 $
Method and assumptions
Volume = length × width × depth, increased by the entered settling allowance. Bag count uses either volume per bag or estimated weight per bag and rounds up once. Weight uses US short tons and editable, approximate material densities; moisture and blend matter. Bagged and bulk costs are separate alternatives and exclude delivery. Confirm actual product coverage and density with the supplier.
General background references
Disclaimer
These calculators provide planning estimates only. Building codes, wiring regulations and safety requirements differ by country and change over time, and nothing here replaces a licensed professional or a permit. For structural, electrical or gas work, follow local code and have the installation inspected.
Implementation source
This record describes the implementation used by this page. It is not independent validation. External references, when available, support only the stated formula or definition; estimates and custom rules retain their own assumptions.
Formula and variables
V_ft³ = L × W × D_in/12 × (1 + allowance/100); V_yd³ = V_ft³/27; mass = V_yd³ × density; bags = ceil(volume/bag volume) or ceil(mass/bag mass)
Bagged and bulk costs are separate alternatives and exclude delivery. Confirm actual product coverage and density with the supplier.
Frequently asked questions
How does the settling allowance affect the soil estimate?
Volume = length × width × depth, increased by the entered settling allowance. Bag count uses either volume per bag or estimated weight per bag and rounds up once. Weight uses US short tons and editable, approximate material densities; moisture and blend matter. Bagged and bulk costs are separate alternatives and exclude delivery. Confirm actual product coverage and density with the supplier.