📋 Table of Contents
- The Core Volume Formula
- Mulch: Depth and Coverage
- Gravel: Depth by Use Case
- Topsoil: Filling and Grading
- Weight vs Volume (Why It Matters When Ordering)
- Three Worked Examples
- Typical Cost Ranges
- Ordering Tips
- Common Ordering Mistakes
- Sustainability Considerations
- Delivery vs Pickup and Placement Labor
- FAQ
The Core Volume Formula
Every bulk landscaping material — mulch, gravel, topsoil, sand, compost — uses the same basic formula:
Then divide by 27 to convert cubic feet to cubic yards, since 1 cubic yard = 3 ft × 3 ft × 3 ft = 27 cubic feet.
The part people get wrong most often is depth — it has to be in feet, not inches, before you multiply. A 3-inch depth is 0.25 feet (3 ÷ 12); a 4-inch depth is 0.333 feet; a 6-inch depth (typical for a gravel base) is 0.5 feet. Skipping this conversion is the single most common ordering mistake, and it produces answers that are off by a factor of 12.
Mulch: Depth and Coverage
Standard mulch depth for garden beds is 2–3 inches — enough to suppress weeds and retain moisture without smothering roots or attracting pests. Piling mulch deeper than 4 inches, or against tree trunks and stems ("mulch volcanoes"), can actually trap moisture and cause rot.
| Depth | Coverage per Cubic Yard | Best For |
|---|---|---|
| 1 inch | ~324 sq ft | Light topdressing, decorative refresh |
| 2 inches | ~162 sq ft | Established beds, annual refresh |
| 3 inches | ~108 sq ft | Standard recommended depth for most beds |
| 4 inches | ~81 sq ft | New beds, weed-heavy areas, playgrounds |
Gravel: Depth by Use Case
Gravel depth depends entirely on what the gravel is doing — decorative gravel needs far less than a load-bearing driveway base:
| Use Case | Recommended Depth |
|---|---|
| Decorative ground cover / mulch alternative | 2 inches |
| Walkway / garden path | 2–3 inches |
| Patio base (under pavers) | 4–6 inches compacted |
| Driveway base layer | 4–8 inches (often in two compacted lifts) |
| French drain / drainage trench backfill | Fills full trench depth |
Topsoil: Filling and Grading
Topsoil is usually ordered for one of three purposes, each with a different depth guideline:
- New lawn establishment: 4–6 inches of quality topsoil over existing subsoil, especially if the existing soil is poor, compacted, or full of construction debris.
- Topdressing an existing lawn: ¼–½ inch spread thinly and raked in, used to level minor low spots and improve soil structure over time.
- Raised beds and planters: Full depth of the bed or container, often blended with compost (a common ratio is roughly 60% topsoil to 40% compost, though gardeners vary this).
Weight vs Volume: Why It Matters When Ordering
Some suppliers sell by the cubic yard (volume); others sell by the ton (weight). Because materials differ in density, a cubic yard of gravel weighs much more than a cubic yard of mulch:
| Material | Approx. Weight per Cubic Yard |
|---|---|
| Bark/wood mulch | ~400–800 lbs (0.2–0.4 tons) |
| Topsoil (dry-ish, loose) | ~2,000–2,600 lbs (1–1.3 tons) |
| Gravel / crushed stone | ~2,800–3,000 lbs (1.4–1.5 tons) |
| Sand | ~2,600–3,000 lbs (1.3–1.5 tons) |
These figures are approximate averages — actual weight varies with moisture content (wet topsoil and wet mulch are noticeably heavier than dry) and the specific stone or wood species. Always ask your supplier for their exact conversion factor if you need a precise tonnage figure for delivery-truck capacity planning.
Three Worked Examples
Example 1 — Mulch bed: A garden bed 20 ft × 10 ft, mulched 3 inches deep.
20 × 10 = 200 sq ft. 200 × 0.25 ft (3 in) = 50 cubic feet. 50 ÷ 27 = ~1.9 cubic yards of mulch.
Example 2 — Gravel path: A path 40 ft long × 3 ft wide, 2 inches deep.
40 × 3 = 120 sq ft. 120 × 0.167 ft (2 in) = 20 cubic feet. 20 ÷ 27 = ~0.74 cubic yards, roughly 1 ton of gravel at ~1.4–1.5 tons/cubic yard.
Example 3 — Topsoil for a raised bed: A raised bed 8 ft × 4 ft, filled 1 ft (12 in) deep.
8 × 4 = 32 sq ft. 32 × 1 ft = 32 cubic feet. 32 ÷ 27 = ~1.2 cubic yards of topsoil (before any compost blend-in).
Typical Cost Ranges
| Material | Typical Bulk Price per Cubic Yard |
|---|---|
| Basic bark mulch | $25–$45 |
| Dyed/premium mulch | $40–$65 |
| Screened topsoil | $20–$40 |
| Crushed gravel/stone | $35–$60 |
| Delivery fee (typical flat rate) | $50–$150 depending on distance and load size |
Prices vary significantly by region, supplier, and how far the load has to travel — treat these as a rough planning range and get a local quote before budgeting a project.
Ordering Tips
- Round up, not down. Suppliers sell in practical increments (often by the ¼ or ½ cubic yard), and running short mid-project usually costs more than a small surplus.
- Measure the actual shape, not a rough guess. Irregular beds should be broken into rectangles and triangles and summed, or measured with an area calculator.
- Ask whether the quoted price includes delivery — bulk material is heavy, and delivery fees can be a significant fraction of small orders.
- For gravel bases, ask your supplier about their specific compaction factor rather than guessing — it varies by gravel type and how you plan to compact it.
Common Ordering Mistakes
- Forgetting to convert inches to feet before multiplying. This is the single most common error — a 3-inch depth is 0.25 feet, not 3. Skipping this step inflates the answer by a factor of 12.
- Measuring only the "visible" bed shape and forgetting curves or borders. Break irregular shapes into simple rectangles and triangles, measure each separately, and add them together rather than eyeballing one combined estimate.
- Not accounting for compaction on base-layer gravel. A loose delivered pile settles significantly once compacted — ordering exactly the "finished depth" volume in loose material will leave you short once it's compacted down.
- Assuming all suppliers price identically by volume. Some sell strictly by the cubic yard, others by the ton — always confirm which unit you're being quoted before comparing prices between suppliers.
- Ignoring delivery minimums. Many bulk suppliers have a minimum order size (often around 2-3 cubic yards) below which delivery isn't offered or carries a disproportionate flat fee — small projects may be cheaper with bagged material despite the higher per-unit cost.
Sustainability Considerations
A few landscaping-material choices have meaningful environmental trade-offs worth factoring into your decision, beyond pure cost:
- Dyed mulch is often made from recycled wood (including reclaimed pallets), which is a positive reuse of waste material, but the dyes themselves vary in composition — look for suppliers who disclose using non-toxic, water-based colorants if this matters to you.
- Cypress and cedar mulch break down more slowly than hardwood mulch, meaning fewer reapplications over time, but sourcing concerns exist around old-growth harvesting for some cypress products — ask suppliers about their sourcing practices.
- Local sourcing reduces transportation emissions for heavy bulk materials and often costs less, since gravel and topsoil are expensive to ship long distances relative to their value.
- Permeable gravel bases (as opposed to solid poured surfaces) allow rainwater to infiltrate rather than run off, which can reduce local stormwater burden — a factor increasingly considered in residential landscaping design.
Delivery vs Pickup and Placement Labor
Bulk material cost isn't just the price per cubic yard — how it gets from the supplier to its final spot in your yard matters for both cost and physical effort. Delivery drops a pile at your driveway or curb, leaving you to wheelbarrow and spread it yourself; many suppliers also offer "spreading" or full installation as an add-on service, typically at a per-cubic-yard labor rate on top of the material cost. For a small bed, self-pickup in a pickup truck bed (rented if needed) and DIY spreading is usually the cheapest option; for anything beyond a couple of cubic yards, or a physically demanding installation like a compacted gravel base, professional delivery and placement often becomes worth the added cost simply in time and physical strain saved.