Garden Soil Calculator
Calculate soil needed for raised beds and gardens. Cubic feet and bags by bed dimensions. Free calculator.
Raised Bed Soil Depth Guide
Lettuce, herbs, radishes: 6-8 inches minimum. Tomatoes, peppers, beans, most vegetables: 12 inches. Carrots, potatoes, parsnips: 18-24 inches for full root development. For most home gardeners, 12 inches covers 90% of common plants. A 4x8 bed at 12 inches deep requires 32 cubic feet. Buying bulk soil from a landscape supply yard ($35-60 per cubic yard) saves 50-60% compared to bagged soil from hardware stores ($5-8 per cubic foot).
The Best Soil Mix
The Mel Mix from Square Foot Gardening: 1/3 compost, 1/3 peat moss (or coconut coir for an eco-friendly alternative), 1/3 coarse vermiculite. This creates a lightweight, well-draining, nutrient-rich medium that produces exceptional garden results. Do not use straight garden soil in raised beds — it compacts, drains poorly, and may contain weed seeds and pathogens. Do not use straight potting mix either — it dries out too quickly and is expensive in volume. The 1/3-1/3-1/3 blend is the proven sweet spot.
One 4x8 raised bed using the Mel Mix method (1/3 compost, 1/3 peat, 1/3 vermiculite) produces as much food as a 100 sq ft traditional row garden — using 80% less space and 90% less water.
