How Much Topsoil, Mulch or Gravel Do I Need? Ordering Bulk in London
To figure out how much topsoil, mulch or gravel you need, measure the area in feet. Multiply length × width × depth (in inches) ÷ 12 to get cubic feet, then divide by 27 to get cubic yards. Typical depths are 2 to 4 inches for mulch, 4 to 6 inches of topsoil for new lawns and gardens, and several inches of gravel depending on use. Round up about 5 to 10%, because material settles and edges are never perfectly square.
Bulk landscape material is sold by the cubic yard, but most homeowners think in square feet. This guide closes that gap so you order the right amount the first time. Our online calculators can also do the math for you.
The cubic yard formula
One cubic yard equals 27 cubic feet (University of Minnesota Extension). Here's the formula step by step:
Measure length and width in feet.
Convert depth to feet: depth in inches ÷ 12.
Multiply length × width × depth (ft) = cubic feet.
Divide by 27 = cubic yards.
Worked examples
Mulch bed: 30 ft × 4 ft at 3 inches deep. 30 × 4 × 0.25 = 30 cubic feet ÷ 27 = 1.1 cubic yards.
Topsoil for sod: 25 ft × 40 ft at 4 inches deep. 25 × 40 × 0.333 = 333 cubic feet ÷ 27 = 12.3 cubic yards.
Gravel path: 40 ft × 3 ft at 4 inches deep. 40 × 3 × 0.333 = 40 cubic feet ÷ 27 = 1.5 cubic yards.
Odd shapes
Circles: area = 3.14 × radius × radius (radius in feet).
Triangles: area = base × height ÷ 2.
Curvy beds: break them into rough rectangles and circles, add the areas, then multiply by depth.
Recommended depths
Use this as a quick reference:
Mulch: 2 to 4 inches. University of Minnesota Extension recommends 2 to 4 inches, with a mulch-free gap around stems and trunks. Don't build a mulch "volcano" against trees.
Topsoil for new sod or seed: often 4 to 6 inches, depending on what's there now. Purdue University notes that about 19 cubic yards gives a 6-inch layer over 1,000 sq ft, and recommends mixing amendments into the native soil at least 6 to 8 inches deep.
Topdressing an existing lawn: a thin layer only, so you don't smother the grass.
Garden beds: enough to give roots a good, loose zone. In heavy London clay, mixing in quality soil and compost helps a lot.
Gravel: depends on use. A decorative layer is thin. Paths, pads and driveways need a compacted base sized for the load, so ask us about your project.
Which material do you need?
Topsoil is for levelling, filling low spots and building a base for new lawns. See our topsoil page.
Mulch goes on garden beds and around trees to hold moisture, moderate soil temperature and suppress weeds. See our mulch options.
Gravel is for driveways, paths, drainage and bases under sheds or patios. See our gravel and aggregate page.
You can browse everything on our landscape materials page from the Shop menu.
Planning the delivery
A good delivery saves hours of wheelbarrow work. Before your truck shows up:
Choose the drop spot. As close to the work area as possible, on a hard, level surface.
Protect the driveway. Lay a tarp or plywood under topsoil and mulch to make cleanup easier.
Check overhead clearance. Dump trucks need room to raise the box, so watch for wires and branches.
Keep the area clear. Move cars and bins out of the way.
Think about the boulevard. Don't block sidewalks, and check your municipality's rules before placing material on city property.
Plan for the weather. Topsoil is easier to spread when it's not soaked. Cover the pile if rain is coming.
Fall is a great time to order
Many people think of bulk materials only in spring, but fall works well too:
Mulch applied in fall insulates roots through freeze-thaw cycles.
Topsoil placed in fall settles over winter, ready for sod or seed in spring.
Gravel for paths and pads can go down any time the ground is workable.
Our fall yard prep checklist has more ideas for getting the yard ready before freeze-up.
Common ordering mistakes
Measuring in the wrong units. Make sure depth is converted from inches to feet.
Forgetting settling. Loose topsoil settles noticeably after watering and rain.
Ordering too deep. Thick mulch or heavy topdressing can hurt plants and lawns.
No plan for leftovers. A small extra pile is handy, but a big one sits on the driveway for weeks.
Splitting orders. Two small deliveries usually cost more than one right-sized one.
Bags vs. bulk: when does bulk make sense?
Garden centres sell mulch and soil in bags, often around 2 cubic feet each. Since a cubic yard is 27 cubic feet, one yard equals about 13 to 14 of those bags. A 3-yard mulch job would mean roughly 40 bags to buy, haul, open and throw away.
As a rough rule of thumb:
Under about half a yard: bags are convenient for touch-ups and small planters.
One yard or more: bulk delivery is usually easier, creates no plastic waste, and is often better value per yard.
Big projects like new lawns, long driveways and large beds: bulk is the only practical way.
Bulk material also tends to be more consistent from one end of the project to the other, since it all comes from the same load.
Quick order checklist
Measure each area and note the depth needed.
Calculate cubic yards for each material.
Add 5 to 10%.
Pick the drop spot and protect the surface.
Call or order with your address, material and quantity.
Local delivery in London and area
SPM has been delivering topsoil, mulch and gravel across London and surrounding communities since 2006, including St. Thomas, Strathroy, Komoka, Ilderton and Dorchester. Prices and availability change by season and material, so check our product pages or call for a current quote.
FAQ
How do I calculate cubic yards?
Multiply length (ft) × width (ft) × depth (in) ÷ 12 to get cubic feet, then divide by 27, because one cubic yard equals 27 cubic feet. For example, a 20 × 10 ft bed at 3 inches deep is 20 × 10 × 0.25 = 50 cubic feet, or about 1.9 cubic yards.
How deep should mulch be?
University extension guidance recommends 2 to 4 inches of mulch, with a mulch-free gap around plant stems and tree trunks. Deeper mulch can starve roots of oxygen, and mulch piled against a trunk can cause rot.
How much topsoil do I need for new sod?
It depends on your existing soil. Purdue University's sod guide notes that about 19 cubic yards of topsoil makes a 6-inch layer over 1,000 sq ft. Many projects need less where the existing soil is decent and only levelling is needed. We can help you size it.
Should I order extra?
A little. Topsoil settles and compacts, mulch beds are rarely perfectly rectangular, and gravel compacts when it's packed down. Rounding up by about 5 to 10% saves a second delivery charge.
Can you deliver to St. Thomas, Strathroy or Ilderton?
SPM delivers topsoil, mulch and gravel across London and surrounding communities. Call (519) 474-0008 to confirm delivery to your address and current pricing.
Talk to SPM Landscape & Excavation
Not sure how much to order? Send us your measurements and we'll help you work out the right amount of topsoil, mulch or gravel for delivery. SPM has served London and southwestern Ontario since 2006, is WSIB covered and carries $1M in liability insurance. Call (519) 474-0008, email spmlandscape@gmail.com, or visit us at 791 Manchester Rd, London, ON.
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