Soil Calculator
Calculate how much soil you need for raised beds, new lawns, garden beds, and grading projects. Get cubic yards with settlement factor and soil type guidance for your application.
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Enter your values above to see the results.
Tips & Notes
- ✓For raised beds taller than 12 inches, fill the bottom third with logs, branches, and rough compost (hugelkultur base) — this reduces the expensive soil volume needed while creating a moisture-retaining substrate that improves over time.
- ✓Mix delivered topsoil with 20–30% compost before planting — most delivered topsoil has low organic content and compacts quickly without amendment.
- ✓Order soil to arrive after you have prepared the area — loose soil left in a pile for more than 3–4 days can develop a crust, and heavy rain can cause significant erosion of an uncontained pile.
- ✓For lawn repair, use a lawn topdressing mix (fine screened topsoil with some sand) rather than garden mix — coarser garden mixes create visible surface irregularities that take seasons to level.
- ✓Request a soil test before importing topsoil for vegetable gardens — soil pH and nutrient levels from delivered topsoil vary widely, and planting into uncorrected soil requires months of amendment to fix.
Common Mistakes
- ✗Using fill dirt instead of topsoil for gardens and lawns — fill dirt is subsoil with no organic matter, poor drainage, and often high clay content. Plants placed in fill dirt fail unless the fill is deeply amended.
- ✗Not accounting for 10–15% soil settlement after watering — freshly placed loose soil always compacts, leaving raised beds and lawn areas lower than intended if the settlement factor is not included in the order.
- ✗Ordering soil by weight (tons) when you need volume (cubic yards) without confirming the weight-to-volume conversion — different soil types have different densities, and a ton of clay fill is much less volume than a ton of light raised bed mix.
- ✗Placing soil directly against a house foundation — soil graded against a foundation holds moisture against the foundation wall, causing water intrusion and eventually structural damage. Soil must slope away from the foundation.
- ✗Skipping a weed barrier when filling raised beds in areas with aggressive rhizomatous weeds (quackgrass, bermudagrass, bindweed) — these weeds grow up through 18+ inches of new soil and are nearly impossible to remove once established.
Soil Calculator Overview
Soil quantity calculation determines how many cubic yards of topsoil, fill dirt, or growing medium you need for raised beds, lawn repairs, grading projects, or garden installations. The calculation is straightforward but frequently results in under-ordering because people forget that loose soil settles 10–15% after watering and compaction, and that delivery minimums often force purchasing slightly more than the precise calculation requires.
Soil volume formula:
Cubic Yards = (Length ft × Width ft × Depth ft) ÷ 27
EX: Raised bed 8 ft × 4 ft × 1.5 ft deep → Volume = 8 × 4 × 1.5 ÷ 27 = 1.78 yd³ → Add 15% settlement = 2.04 yd³ → Order 2 yd³ or 2.25 yd³ depending on supplier minimumSoil types and their applications:
| Soil Type | Weight per yd³ | Best Application | Drainage | Organic Content |
|---|---|---|---|---|
| Premium topsoil | ~1.1 tons | Lawn repair, topdressing | Moderate | Low to moderate |
| Garden mix (topsoil + compost) | ~0.9 tons | Garden beds, planting areas | Good | High |
| Raised bed mix | ~0.7 tons | Raised beds, containers | Excellent | Very high |
| Sandy loam | ~1.2 tons | Drainage improvement, sports fields | Very good | Low |
| Fill dirt (clay) | ~1.5 tons | Grading, filling depressions | Poor | None |
| Compost (finished) | ~0.8 tons | Soil amendment, topdressing | Good | Very high |
| Application | Minimum Depth | Recommended Depth | Notes |
|---|---|---|---|
| Lawn repair / overseeding | ¼ in | ½–1 in topdressing | Spread and rake level with existing grade |
| New lawn installation | 4 in | 6 in | Rototill into existing soil for best results |
| Annual flower bed | 6 in | 8–10 in | Shallow-rooted annuals; compost-rich mix |
| Perennial garden | 12 in | 18 in | Deep roots require substantial soil depth |
| Raised vegetable bed | 12 in | 18–24 in | Deeper beds allow taproot vegetables |
| Grade correction | Varies | Slope away from foundation at 6 in/10 ft | Use fill dirt, not topsoil, for structural grading |
Frequently Asked Questions
Calculate: Length × Width × Height ÷ 27. For an 8×4 ft bed at 12 inches deep: 8 × 4 × 1 ÷ 27 = 1.19 yd³. Add 15% for settlement: 1.37 yd³ — order 1.5 yd³. For an 8×4 ft bed at 18 inches: 8 × 4 × 1.5 ÷ 27 = 1.78 yd³ + 15% = 2.05 yd³ — order 2 yd³. Most soil suppliers have a 1 cubic yard minimum for delivery.
Topsoil is the upper 4–12 inches of native soil, containing organic matter and soil structure suitable for plant growth. It is used for lawns and general planting areas. Fill dirt is subsoil — deeper material with no organic content, used strictly for structural grading, filling depressions, or building up grade. Never plant in fill dirt without deep amendment. Garden mix (also called planting mix) is a blend of topsoil and compost, with higher organic content specifically formulated for vegetable and ornamental gardening.
Aim for 6 inches of quality topsoil for a new lawn. For a 1,000 sq ft lawn at 6-inch depth: 1,000 × 0.5 ÷ 27 = 18.5 yd³. At 4-inch depth (minimum): 12.3 yd³. Add 15% for settlement: 14–21 yd³ depending on target depth. For comparison, 1 cubic yard of topsoil covers approximately 108 sq ft at 3 inches, 81 sq ft at 4 inches, or 54 sq ft at 6 inches.
Neither alone — the best vegetable garden soil is a mix of both. A common professional blend is 60% quality topsoil + 30% compost + 10% perlite or coarse sand for drainage. This creates a nutrient-rich, well-draining, moisture-retaining medium that most vegetables thrive in. Pure topsoil compacts and drains poorly. Pure compost dries out quickly and is too light for some root vegetables. The blend provides the structure of soil with the nutrition and drainage of compost.
Break the irregular shape into rectangles and triangles. Calculate each section separately: rectangles = length × width, triangles = 0.5 × base × height. Sum all sections for total square footage. Multiply by desired depth in feet (inches ÷ 12) and divide by 27 for cubic yards. For very irregular shapes, overestimate by 10% — it is always easier to return a partial cubic yard than to order a second delivery.
The Mel Bartholomew Square Foot Gardening mix (popularized in mainstream gardening) is one-third each of: blended compost, coarse vermiculite (for drainage and water retention), and peat moss (for acidity and water retention). For larger quantities, a more economical version is 50% quality topsoil + 25% finished compost + 25% perlite or coarse sand. Avoid mixes with more than 30% peat moss — very high peat content creates soil that compacts into a difficult-to-rewet brick when dry.