Soil volume
The calculator converts measurements to a consistent unit and applies the rectangular-prism formula: length × width × soil depth × number of beds. Results are converted between cubic feet, cubic yards, litres and cubic metres. Bag count divides the volume plus the selected reserve by the volume of one bag, then rounds upward.
Visual grid
The layout rounds bed length and width to an approximately one-square-foot grid, limited to a practical on-screen size. The soil volume always uses the exact measurements, so rounding the visual grid does not alter the shopping calculation.
Plant density
Crop densities translate common final plant spacing into a square grid. For example, a three-inch spacing produces a four-by-four arrangement, or sixteen positions per square foot. The values are deliberately presented as starting points because cultivar, climate, soil fertility, training method and disease pressure affect suitable spacing.
Reference material
- Colorado State University Extension — Block Style Layout in Raised Bed Vegetable Gardens
- University of Florida IFAS Extension — Square-Foot Garden
- Utah State University Extension — Raised Bed Gardening
- University of New Hampshire Extension — Intensive Vegetable Gardening
Limitations
The tool does not select crops for a climate, calculate frost dates, diagnose soil or determine structural safety. Seed packets and local extension recommendations should override generic spacing.