How to use this calculator
- Choose an area mode. Rectangle for beds, lawn sections, and fills measured edge to edge; circle for round areas measured by diameter; multiple areas for several spots in one project — each area gets a name, a shape, and its own depth.
- Enter dimensions and depth. Depth accepts inches or feet (US) and millimetres, centimetres, or metres (metric), per area. The depth presets are conveniences for entering common values — the depth that suits your project depends on what you are doing and what is already there, so check your product's guidance.
- Set a waste allowance for uneven ground, low spots, and spreading. 10% is a starting point, not a rule — rough ground and deep fills justify more.
- Pick a purchasing method. Bagged: choose a bag-size preset or type any size from the label, and optionally a price per bag. Bulk: optionally set a purchase increment (e.g. whole cubic yards) and a price per yard. The two methods are alternatives — compare them, never add them.
The formulas
Circle: area = π × (diameter ÷ 2)²
Volume = area × depth
Required volume = base volume × (1 + waste %)
Bags = required volume ÷ volume per bag → round up to whole bags
Bulk order = required volume, rounded up to your purchase increment
Multiple areas each use their own depth, and their volumes are added before the waste allowance is applied. Bag quantities always round up to whole bags — partial bags cannot be bought. Bulk quantities keep the exact fractional figure unless you configure an increment.
Worked example
A 12 × 8 ft section of yard to level out, 4 inches deep, 10% waste, 1 cu ft bags at an assumed $3.50 each:
| Step | Result |
|---|---|
| Area: 12 × 8 | 96 sq ft |
| Volume: 96 × (4 ÷ 12) | 32 cu ft ≈ 1.19 cu yd |
| Required with waste: 32 × 1.10 | 35.2 cu ft |
| Bags: 35.2 ÷ 1 | 35.2 → round up |
| Purchase quantity | 36 bags |
| Cost at $3.50 per bag | 36 × $3.50 = $126.00 |
The bag price is an example, not a market claim — enter the price on the shelf tag, or leave it empty and the calculator shows quantities only.
Bagged vs bulk — comparing what suppliers actually quote
Bags quote a volume per bag (commonly 0.75–2 cu ft in the US, 25–60 L elsewhere); bulk suppliers quote a price per cubic yard or cubic metre. To compare, put both on the same basis: a 1 cu ft bag is 1 ÷ 27 ≈ 0.037 cubic yards, so a $3.50 bag works out to about $94.50 per yard at that assumption. Divide your own bag's price by its volume, compare against the bulk quote, and let the delivery fee and how far you are hauling bags decide. The calculator prices whichever method you select from your own numbers — it never mixes them.
Topsoil depth — what it depends on
The depth you need depends on the project: filling low spots takes whatever the grade requires, while the depth for planting areas depends on what is already there, what you are growing, and the product's own guidance. That is why the presets here are labeled as conveniences rather than advice, and why the calculator does not add extra depth for settling on its own — topsoil settles once spread and watered, especially in deep fills, so how much extra you budget is your call.
Waste allowance — what it actually covers
Uneven ground, low spots that swallow material, irregular edges, and how you spread all consume topsoil. How much extra you need depends on your site — rough terrain and deep fills need more than a smooth, shallow topdressing. There is no universal number, which is why the field is editable and the base, waste, and required volumes are all shown separately.
Common mistakes
- Measuring the surface but not the dips — walk the area and note low spots, since uneven ground needs more material than the flat footprint suggests.
- Comparing a per-bag price against a per-yard price without converting through bag volume — pick one basis and compare like with like.
- Adding the bagged total and the bulk total together — they are two ways to buy the same pile, never two piles.
- Forgetting that topsoil settles — a fill that reads perfectly level right after spreading will sit lower once watered and compacted, especially in deep fills.
- Assuming all "topsoil" is the same product — screened, blended, and enriched soils vary widely in composition and suitability, so check the product description for your use.
This is a material estimation tool only. Topsoil products vary widely in composition and suitability — check the product description for your use, and consult your local extension service or a landscape professional for soil-health or plant questions.
FAQ
How much topsoil do I need for a 12 × 8 ft area?
The area is 96 sq ft. At 4 inches deep: 96 × 4 ÷ 12 = 32 cubic feet, about 1.19 cubic yards (one cubic yard is 27 cubic feet). With a 10% waste allowance that becomes roughly 35.2 cubic feet — 36 one-cubic-foot bags or 18 two-cubic-foot bags. The Topsoil Calculator runs this same math for any shape and depth.
How many bags of topsoil are in a cubic yard?
A cubic yard is 27 cubic feet. That is 36 one-cubic-foot bags, 27 one-and-a-half-cubic-foot bags, or about 13.5 — so 14 — two-cubic-foot bags. To compare bag prices against a bulk quote per yard, divide the bag price by the bag's volume in cubic yards and compare the per-unit figures.
What depth of topsoil should I use?
It depends on the project and the site — whether you are filling low spots, leveling, topdressing, or creating new beds — plus what is already there and the product's own guidance. There is no single universal depth, which is why the presets in the calculator are conveniences for entering a value, not recommendations. For planting-specific depth questions, check your product's label or ask your local extension service.
Is bagged or bulk topsoil cheaper?
It depends entirely on local prices, which is why none are invented here. The comparison method is fixed: convert both quotes to the same unit. Divide a bag's price by its volume in cubic yards (or litres into cubic metres) and compare that per-unit figure against the bulk price. Bulk usually wins on large fills; bags usually win on small areas and convenience. Enter both in the calculator and compare the totals.
Does the estimate include delivery, spreading, or settling?
No. The estimate covers material quantity only — delivery, taxes, minimum-order charges, spreading labor, and site preparation are extra. Topsoil also settles after spreading and watering, especially in deep fills; the calculator does not silently add extra depth for that, so budget additional material if the grade matters.