ToolMix Lab Find a tool
Menu

Garden & groundwork

Topsoil & raised bed calculator

Calculate new soil for raised beds or surface layers, allowing for headroom, existing material, bags and bulk increments. Review the method, a worked example and the limits before using your result.

Free · No account needed

GARDEN PLANNING · SOIL ESTIMATOR

Topsoil & raised bed calculator

Estimate soil for raised beds or a new surface layer. Use inside dimensions and compare bags with bulk delivery.

JavaScript is required. If this message remains visible, the calculator script has not loaded.

—
Soil project inputs
1Beds & surface areas

Choose individual units

US dry qt is a dry-volume unit, not a liquid quart. Mass-only bags (kg/lb) need the supplier’s volume; weight alone is not enough.

For raised beds, enter inside dimensions and internal height above the bed bottom. Existing soil and bottom filler are separate deductions. For a surface layer, do not count the underlying natural ground as retained material.

Use separate rectangles for an L-shape. Different rows may have different tasks and depths; all share one soil product. Positions between beds are not inferred.

2Order quantities

Editable allowance for handling or uneven spreading. No automatic settling factor.

Use the labelled volume of soil in one bag. No bag size is assumed. kg/lb are mass and cannot be used as volume.

0 = exact volume. Otherwise round up to your supplier’s order increment, e.g. 0.25 yd³.

3 · Compare prices (optional)

One charge for the whole order. Enter 0 if none.

One charge for the whole order. Enter 0 if none.

Blank means unknown; 0 means free. Currency changes the label, not an exchange rate. Enter current quotes; no prices are assumed.

How to use

  1. Choose raised-bed fill or a surface layer. Enter internal dimensions and the shape of each non-overlapping zone.
  2. For beds, specify inside height, headroom, lower filler and suitable existing soil. For surface layers, enter the target added layer and the usable existing part within it.
  3. Add exclusions where supported, choose an allowance and select bulk or a bag volume from your product label.
  4. Compare geometric need, target order and purchase rounding. Use the correct volume unit when entering a bulk price or increment.

Calculation method

Raised-bed new depth is the internal height minus headroom, lower filler and existing soil depth above that filler. Surface-layer depth is the target layer minus the existing suitable portion within that layer. Area × new depth × quantity gives volume. The allowance is applied once. Bags round target volume up by bag volume; bulk ordering rounds to the chosen increment when nonzero. Mass is not inferred from an assumed soil density.

Worked example

A bed with internal dimensions 2 × 1 m, internal height 40 cm and 5 cm headroom needs 2 × 1 × 0.35 = 0.7 m³, or fourteen 50 L bags. With a 10 cm lower filler and 5 cm existing soil above it, new soil depth is 20 cm and volume 0.4 m³. A 10% allowance makes 0.44 m³: nine 50 L bags or 0.5 m³ at a 0.25 m³ bulk increment.

Assumptions and limits

The starting geometry is an example, not a recommendation for root depth, filler composition or soil suitability. Measurements must be internal. Do not count lower filler again as existing soil. Separate rows do not detect overlap with one another. US dry quarts, litres and cubic feet describe distinct volume units; check the label.

Continue your plan

Plan a separate surface covering with the mulch calculator, check general solids with the volume calculator, or verify a footprint with the area calculator.

Copy, download or print a valid result to keep the inputs with the estimate. Currency selections label your prices; they do not apply an exchange rate. Product-dependent examples should be replaced with data for the material or equipment you actually use.

For the measurement and planning details, read measuring raised-bed fill, headroom and existing soil.