EstimatorKitFree area-to-volume converter
Square feet to cubic yards needs one more number
There is no conversion factor between square feet and cubic yards, because one counts a surface and the other counts a space — the missing term is how thick the layer is. Give the square footage you already have and name the job, and the depth is filled in for you: four inches for a slab, three for mulch, one for bedding sand, six for a driveway base. The answer comes back as bare cubic yards, as the larger figure that has to be placed where the material settles, and as the whole yards a supplier will put on the invoice.
- 100% free
- No signup
- 6 job depths
- Settling shown separately
- Whole yards out
There is no factor between the two units. Square feet counts surface and cubic yards counts space, so the conversion needs a thickness before it exists. Pick the job below and the missing number is filled in for you.
Four inches carries foot traffic, patio furniture and a parked car on a prepared base.
500 sq ft at 4 in
6.17 cu yd
- Whole yards to order
- 7
- One yard covers
- 81 sq ft
Nothing is added to this one. A concrete slab is placed at the thickness it finishes at, so the geometry is the order — the padding you may still want is for over-excavation and spillage, and that is a judgement about your site rather than a property of the material.
Worked the long way: 500 sq ft × 0.33 ft = 167 cu ft, then divided by 27.
What one cubic yard covers
Divide your square footage by the middle column to get cubic yards at that thickness. The pattern is worth memorizing: the coverage halves every time the depth doubles.
| Thickness | One cubic yard covers | Where that thickness turns up |
|---|---|---|
| 1 inch | 324 sq ft | Bedding sand screeded flat under pavers |
| 2 inches | 162 sq ft | Compost worked into the surface of a bed |
| 3 inches | 108 sq ft | Shredded bark in a planting bed |
| 4 inches | 81 sq ft | A slab on prepared ground, or topsoil over a new lawn |
| 6 inches | 54 sq ft | Base stone under a drive that takes delivery vans |
| 8 inches | 40.5 sq ft | Backfill in a trench, or a heavy approach build-up |
| 12 inches | 27 sq ft | Filling a raised bed a foot deep |
How to convert square feet to cubic yards
Two numbers in, and the second one is the whole point.
Put in the square footage you already have
This field takes the number, not the measurements — the figure off a plan, a deed, a quote or a tape you have already multiplied out. Commas and a trailing unit are ignored, so 1,250 and 1250 sq ft both land the same. If you do not have the area yet, that is a separate job and a separate page; this one assumes it is settled.
Say how thick the layer is by naming the job
This is the term the two units are missing, and it is the only reason there is no direct conversion. Choosing a job fills the thickness in with a figure that suits it — an inch of bedding sand behaves nothing like six inches of base stone — and the field stays editable for anything specified on a drawing. Nothing here can be calculated without it, so the tool asks rather than assuming.
Take the bare figure and, where it applies, the placed one
You get the volume the geometry produces and, for the two jobs that lose thickness after they go down, a second figure showing what has to be placed to finish at the depth you asked for. Both are shown because only the first can be checked against a quote and only the second will finish flush. Under it is the whole-yard figure a supplier will actually invoice.
Technical specifications
| What the conversion needs | A thickness — one unit counts surface, the other counts space |
|---|---|
| Job presets | Six: concrete slab 4 in, mulch 3 in, bedding sand 1 in, driveway base 6 in, lawn topsoil 4 in, compost 2 in |
| Area entry | A plain count of square feet; a thousands comma or a trailing sq ft is ignored |
| Thickness entry | Inches unless stated; 3/4, 1 1/2, 0.5 ft and 40 mm all read |
| Compaction allowance | 20% on base stone, added as a separate line and never into the first |
| Settling allowance | 15% on topsoil and compost, applied and shown the same way |
| Coverage at one inch | 324 sq ft per cubic yard, halving every time the thickness doubles |
| Sent anywhere | No — the square footage and the thickness stay in this browser |
Frequently asked questions
Can square feet be converted to cubic yards on their own?
No — the two units count different dimensions, so there is no number to multiply by. Square feet describes a surface with length and width; cubic yards describes a space with length, width and thickness. Any tool that answers without asking how deep the material goes has silently chosen a depth for you, and it is usually one inch or one foot, which are the two most likely to be wrong.
What is 1,200 square feet at 4 inches deep in cubic yards?
14.81 cubic yards, which a supplier will invoice as 15. The arithmetic is 1,200 × 0.3333 ft = 400 cubic feet, and 400 divided by 27 is 14.81. Change nothing but the depth and it moves hard: the same area at 2 inches is 7.4 yards and at 6 inches it is 22.2, which is the clearest demonstration of why the thickness is not a detail.
Is dividing square feet by 324 a valid shortcut?
Only for a layer exactly one inch thick. The 324 comes from 27 cubic feet spread an inch deep, and the divisor changes for every other depth — 108 at three inches, 81 at four, 27 at a foot. It circulates as a rule of thumb with the depth quietly stripped out of it, which is how people end up ordering four times what they need.
Does the shape of the area change the answer?
No. Once an area is expressed in square feet, its outline has stopped mattering — 400 square feet of kidney-shaped bed and 400 square feet of rectangle take exactly the same volume at the same thickness. What the shape does change is how much you waste at the edges, because curves and points are where material gets over-spread and where offcuts happen.
Why do base stone and topsoil need more than the calculation says?
Because they lose thickness after they are placed. Loose aggregate gives up roughly a fifth of its depth once it is plated or rolled to grade, and screened topsoil and compost settle by around fifteen percent after they are watered in. Both allowances appear here as a second, clearly labeled figure rather than being added into the first, so the quantity you check against a quote and the quantity that finishes flush are both visible.
The quote is per square foot and the yard sells by the cubic yard — how do I check it?
Convert the quoted area to a volume at the specified thickness, then price that volume at the yard's rate. A contractor quoting a square-foot price for a supply-and-lay job is bundling the material, the labor and the waste, so the material line you calculate here should come out below their number; if it comes out above, the specified depth in the quote is thinner than what you assumed.
About converting an area into a volume
This search is one of the few where the honest answer starts with a refusal. Square feet and cubic yards are not two scales of the same thing, the way inches and feet are; they have different dimensions, and a factor between them cannot exist. Check it the way an engineer would: feet squared multiplied by feet gives feet cubed, and there is no arrangement of the two units that produces the third without something of length dimension in the middle. Every working answer to this question therefore contains a thickness, and the only difference between tools is whether they tell you which one they used.
That is where the rules of thumb come from and why they misfire. Divide by 324 and you have assumed an inch. Divide by 27 and you have assumed a foot, which for a mulch bed is four times too much material and the reason someone ends up with a delivery they cannot spread. Those numbers are perfectly correct at their own depth — the table above is nothing but the same division at seven thicknesses — but they travel without the condition attached, and by the time they reach a forum post the depth has been stripped off entirely. If you have been given a divisor, ask what depth it assumes before you multiply anything by it.
The second thing this page does is keep the settling allowance out of the headline figure. Base stone loses about a fifth of its depth under a compactor and topsoil about fifteen percent once it is watered, so both need to be placed thicker than they finish; that adjustment is printed as its own line so you can check the bare volume against a supplier’s quote and still order enough. Once you have the yards, the delivery itself — minimum loads, short-load fees and how many trips it is — is the cubic yard calculator, and if the yard prices by weight instead, tons to cubic yards carries the density for each material. For land measured in acres rather than square feet, start at the acre calculator; for a drive being surfaced rather than based, the asphalt calculator works in the compacted thickness the paving crew will quote.
What this page does with your square footage
Every number on this page is worked out by JavaScript running in the tab you are reading it in. Nothing you type — measurements, quantities, the prices your supplier quoted you — is uploaded, logged or kept, which is also why the calculators carry on working on a site with no signal.
A square footage plus a job description is close to an address, which is a good enough reason not to collect either. The two numbers exist only in this tab, and the page has no form to submit them through.