The Formula
Topsoil is sold by the cubic yard. The calculation is always the same: area times depth, converted to cubic yards.
A lawn 30 ft × 20 ft getting a 4-inch (0.33 ft) layer of topsoil:
30 × 20 × 0.33 ÷ 27 = 7.3 cubic yards.
For irregular shapes or multiple areas, the topsoil calculator adds them together and includes a waste buffer automatically.
How Deep Should Topsoil Be?
Depth depends entirely on what you're doing. Too shallow and roots can't establish; too deep adds cost without benefit.
| Use case | Recommended depth |
|---|---|
| Top-dressing existing lawn | 2–3 inches |
| New lawn from seed | 4–6 inches |
| New lawn from sod | 4–6 inches |
| Raised vegetable beds | 8–12 inches |
| Flower and shrub beds | 6–8 inches |
| Filling low spots | As needed to level |
For raised vegetable beds, depth matters more than anywhere else — roots need room. Skimping on depth in a raised bed is the single most common reason vegetables underperform.
Types of Topsoil
Not all topsoil is the same. The right type depends on what you're growing and what's already in your ground.
Screened Topsoil
The most common bulk option. Passed through a screen to remove large rocks, roots, and debris. Good general-purpose soil for lawns and beds. Quality varies widely between suppliers — ask about the source and whether it's been tested. Dark colour and a loose, crumbly texture are good signs.
Blended / Garden Mix
Topsoil mixed with compost, aged manure, or other organic matter. Better structure, better drainage, and more nutrients than plain screened topsoil. Costs more but worth it for vegetable gardens and new beds where you want plants to establish quickly. Often sold as "garden mix" or "planting mix."
Sandy Loam
A blend of sand, silt, and clay that drains well without drying out too fast. Ideal for lawns and any situation where drainage is a concern. If your existing soil is heavy clay, sandy loam on top helps balance drainage over time.
Fill Dirt vs. Topsoil
Fill dirt is subsoil — it has little to no organic matter and won't support plant growth on its own. It's cheaper and fine for raising grade or filling large low spots, but always needs 4–6 inches of topsoil over it before planting or seeding. Never confuse the two when ordering.
Coverage Per Cubic Yard
Quick rule of thumb: one cubic yard covers 100 sq ft at 3 inches deep. Halve the coverage for every extra 3 inches of depth.
Cost Estimate
Bulk topsoil is almost always cheaper than bagged once you need more than 1–2 cubic yards.
A 40 lb bag covers roughly 6 sq ft at 3 inches deep — barely enough for a small bed. For anything larger than a few square feet, bulk delivery wins on both cost and convenience. Most suppliers have a delivery minimum of 2–3 cubic yards; if your project is smaller, bagged topsoil avoids the delivery fee.
Before You Order — Checklist
- Add 10–15% for waste. Topsoil settles after delivery and watering. Order a little extra so you're not short at the edges or in low spots.
- Test your existing soil first. A basic soil test (under $20 at most garden centers) tells you what's missing. Buying the wrong topsoil type can make a pH or drainage problem worse, not better.
- Know fill dirt vs. topsoil. If you're raising a grade significantly, use cheaper fill dirt for the bulk and top with 4–6 inches of topsoil. Ordering all topsoil for a large fill job is expensive and unnecessary.
- Check delivery access. A cubic yard of topsoil weighs roughly 1–1.5 tons. Confirm the truck can reach your drop point without damaging a lawn or driveway. Most suppliers will dump at the curb if access is tight.
- Plan to spread within 24–48 hours. A pile of topsoil left sitting compacts, can kill the grass underneath, and is a neighbourhood eyesore. Have your tools and time lined up before delivery.
- Don't bury existing grass too deep. Covering an established lawn with more than 2–3 inches of topsoil can suffocate it. For deeper applications, remove the existing turf first.
Common questions
How many bags of topsoil do I need?
A standard 40 lb bag covers about 6 sq ft at 3 inches deep. Divide your total square footage by 6 to get the number of bags. For anything over 20–25 bags, bulk delivery will be cheaper. The topsoil calculator gives you the bag count automatically.
How much does a cubic yard of topsoil weigh?
Roughly 1,000–1,500 lbs depending on moisture content and soil type. Wet topsoil after rain can be significantly heavier. This matters for delivery — most pickup trucks can safely carry about half a cubic yard; anything more needs a dedicated delivery truck.
Can I put topsoil over existing grass?
Yes, but depth matters. Up to 2–3 inches over an existing lawn is fine — grass can grow through it. More than that and you risk suffocating the turf. For deep applications (4+ inches), remove the existing grass first with a sod cutter or by tilling.
What's the difference between topsoil and compost?
Topsoil is the mineral-based upper layer of soil — it provides structure and holds roots. Compost is decomposed organic matter — it adds nutrients and improves drainage. They work together: topsoil for volume and structure, compost mixed in for fertility. Many garden mixes combine both.
How long does it take topsoil to settle?
Expect 10–20% settling over the first few weeks as air pockets compress and the soil compacts with rain and foot traffic. For a lawn, this means your first seeding might show low spots after a few weeks — a light top-dressing the following spring is normal and expected.