Topsoil Calculator

How this is calculated

Volume is length times width times depth, with the depth converted from inches to feet. Cubic feet become cubic yards by dividing by 27. ⚠️ TOPSOIL SETTLES, AND THE ALLOWANCE IS LARGER THAN PEOPLE EXPECT. Soil delivered loose is full of air. Once it is spread, watered and walked on it compacts, and a bed filled level on the day sits noticeably low within a few weeks. A 20 to 25 percent allowance is normal, which is why the settling input defaults to 20 rather than to a token 5. That means the depth you order for and the depth you want are different numbers. Enter the FINISHED depth you are after and let the allowance do its work. DEPTH DEPENDS ENTIRELY ON THE JOB, and this is where most of the error lives: Topdressing an existing lawn - a quarter to half an inch, no more. Burying grass kills it. Seeding a new lawn - 4 to 6 inches of decent soil over the subsoil. General planting beds - 8 to 12 inches. Vegetable beds and deep-rooted planting - 12 inches or more. A quarter inch and twelve inches differ by a factor of forty-eight, so the depth input matters far more than getting the area exactly right. TONS OR CUBIC YARDS: suppliers are split, exactly as they are for gravel, and the numbers are not close. Topsoil density varies enormously with moisture - dry screened soil runs lighter and wet soil substantially heavier - so the density is an input rather than a constant. A commonly used figure is around 1.1 tons per cubic yard for screened topsoil, and wet soil can be well over that. ASK your supplier which unit they price in and what density they use. ⚠️ TOPSOIL IS NOT A GRADED PRODUCT in the way sand or gravel is. Quality varies wildly between suppliers - screened, unscreened, sandy, clay-heavy, full of stones or weed seed. Cheap topsoil that is mostly subsoil and builders' rubble is a common and expensive disappointment, because you pay to have it delivered and then pay again to remove it. Ask what it is, where it came from, and whether it is screened. BUYING BAGGED IS FOR SMALL JOBS ONLY. Bags are convenient and cost several times what bulk does per cubic yard. The crossover is usually somewhere around one cubic yard, which is about 27 bags of one cubic foot - at which point a bulk delivery is cheaper and one trip rather than several. Not included: the weight, which for anything beyond a small bed is the real constraint on doing it yourself, and where the lorry can tip.

Common questions

Why is the settling allowance so large?

Because soil delivered loose is full of air. Once it has been spread, watered and walked on it compacts substantially, and a bed filled level on the day will sit noticeably low within a few weeks. Twenty to twenty-five percent is normal, which is why the default is 20 rather than a token 5. The practical consequence is that the depth you ORDER for and the depth you WANT are different numbers - so enter the finished depth and let the allowance handle the rest.

How deep should it be?

It depends entirely on the job, and this input matters far more than measuring the area precisely. Topdressing an existing lawn wants a quarter to half an inch and no more, because burying grass kills it. Seeding a new lawn wants 4 to 6 inches of decent soil over the subsoil. General planting beds want 8 to 12, and vegetable beds or deep-rooted planting 12 or more. A quarter inch and twelve inches differ by a factor of forty-eight - get this wrong and nothing else on the page can save the order.

Tons or cubic yards?

Whichever your supplier prices in, and you must ask, because the two numbers are not close - exactly the same trap as buying gravel. Topsoil density also varies enormously with moisture: dry screened soil runs lighter and wet soil substantially heavier, so it is an input here rather than a fixed constant. A commonly used figure is around 1.1 tons per cubic yard for screened topsoil. Ask your supplier both which unit they sell by and what density they are using.

Is cheap topsoil a false economy?

Very often, and this is the biggest risk on the whole purchase. Topsoil is not a graded product the way sand and gravel are - quality varies wildly between suppliers, and cheap loads can be largely subsoil, builders' rubble, stones or weed seed. That is expensive twice over, because you pay to have it delivered and then pay again to remove it, plus whatever it costs you in a bed that will not grow anything. Ask what it is, where it came from, and whether it has been screened.

Should I buy bags or bulk?

Bags are for small jobs only. They are convenient and cost several times what bulk does per cubic yard, and the crossover comes sooner than people think - roughly one cubic yard, which is about 27 one-cubic-foot bags. Beyond that a bulk delivery is cheaper and it is one trip instead of several. The bag count output exists mainly so you can see the number before deciding bags are the easy option.

What about the weight?

For anything beyond a small bed it is the real constraint, and it is why the pounds figure is on the page. Topsoil is heavy, wheelbarrows hold less than you think, and the distance from where a lorry can tip to where the soil needs to go is what decides whether this is an afternoon or a weekend. Work that out before the delivery arrives rather than while it is sitting on your driveway.

Take it further with AI

Copy this into ChatGPT or Claude with your own numbers filled in. It hands over the figures this calculator worked out, so the answer is built on real arithmetic instead of a guess.

I used the Topsoil Calculator at https://www.bfcbrilliance.com/tools/topsoil-calculator.

What I entered:
- Length (ft): ___
- Width (ft): ___
- FINISHED depth you want (in): ___
- Settling allowance (%): ___
- Density (tons/cu yd): ___

What it calculated:
- Topsoil to order: ___
- In tons: ___
- In cubic feet: ___
- If you bought 1 cu ft bags: ___
- Loose depth you must spread: ___

Use those figures as given — they are already worked out, so please don't recalculate or estimate your own. Help me turn them into a plan: what to buy or do, in what order, roughly what it should cost, and the mistakes people most often make with this job.

Where the job touches structure, gas, or electrics, tell me to check local building code and whether a permit or a licensed trade is required.

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