Construction & Materials
Concrete Calculator
Concrete: it computes concrete volume as length × width × thickness and converts it to cubic yards or cubic metres. Worked through below with real figures, and the calculator repeats the working on your own inputs — free, on-device, instant.
Concrete Calculator lets you estimate concrete volume in seconds: enter your slab length, slab width and slab thickness for the volume in cubic yards or metres, all worked out locally in your browser.
Estimate only — not engineering or structural advice. Volume and quantity depend on the dimensions you enter and the product's yield or density; allow for spillage and over-ordering and confirm the mix with your supplier.
About this calculator
It matters before you buy: a clean volume estimate plus a waste allowance beats a guess every time. The governing relationship: It computes concrete volume as length × width × thickness and converts it to cubic yards or cubic metres. See it on real numbers: For a slab measuring 5 m × 4 m × 0.10 m , the wet volume is 5 × 4 × 0.10 = 2.0 m³ . For a 1:2:4 nominal mix the dry volume is taken as wet × 1.54 ≈ 3.08 m³ , of which cement is about 3.08 ÷ 7 ≈ 0.44 m³ ≈ 12–13 bags (one 50 kg bag ≈ 0.0347 m³). The calculator above applies the same steps to whatever you enter — computed locally, nothing sent anywhere.
How to use
- Enter the slab length in feet.
- Enter the slab width in feet.
- Enter the slab depth in inches.
- Tap Calculate to see cubic feet, cubic yards, and bag counts.
Why use the Concrete Calculator
Instant
Every quantity is worked out on your device the moment you tap Calculate.
Private
The numbers you enter stay in your browser and are never uploaded or saved.
Free
No signup, no paywall, and no ads placed inside your results.
Works offline
Once the page has loaded it keeps working on a weak or dropped connection.
Mobile-first
Laid out for phones and tablets on site just as much as for desktops.
Planning estimates
Results are simplified planning estimates; real material needs vary by product size, waste, layout, local codes, and site conditions, so confirm before you buy or build.
Common uses
Use it when adding a waste margin
Use it for estimating concrete, cement or asphalt volume
Use it when planning a footing or path
Use it when budgeting a pour
Use it when ordering by cubic yard or metre or by bag
Use it for a quick volume estimate
Technical notes
Concrete Calculator computes concrete volume as length × width × thickness and converts it to cubic yards or cubic metres.
A volume estimate from the dimensions you enter; allow for settling, compaction or spillage and round up when ordering.
Results are rounded for display; the underlying calculation keeps full precision.
Worked example
For a slab measuring 5 m × 4 m × 0.10 m, the wet volume is 5 × 4 × 0.10 = 2.0 m³. For a 1:2:4 nominal mix the dry volume is taken as wet × 1.54 ≈ 3.08 m³, of which cement is about 3.08 ÷ 7 ≈ 0.44 m³ ≈ 12–13 bags (one 50 kg bag ≈ 0.0347 m³). Add roughly 5% for wastage. This is an example only — mix design, density and local practice vary.
FAQ
Is the depth entered in inches?
Yes. Enter the slab depth in inches; the tool divides it by 12 to convert to feet for the volume.
Does the Concrete Calculator send my numbers anywhere?
No. The Concrete Calculator runs in your browser and the values you enter are never uploaded.
How are the bag counts estimated?
Volume in cubic feet is divided by an approximate yield of 0.5 cubic feet for a 50-pound bag and 0.6 for an 80-pound bag.
Should I add extra for spillage?
Yes. Order a little more than the estimate to allow for spillage, uneven subgrade, and over-excavation.