About
About Us
ConcreteCals is a free, browser-based concrete calculator built to make material estimating faster, clearer, and easier to check. No account, no sign-up, and no project data sent to a server.
Why we built ConcreteCals
Concrete math is not complicated, but it is easy to get wrong. A thickness entered in inches, a diameter confused with a radius, or a missing waste allowance can turn a one-truck pour into a short load and a second delivery fee.
Plenty of calculators will give you a number. Fewer show the assumptions behind it. We built ConcreteCals to put the working figures in one place — cubic yards, cubic metres, cubic feet, bag counts, and cost — with the units visible at every step.
The goal is not to replace your supplier or your engineer. It is to help you ask better questions, compare quotes with confidence, and order the right amount of material the first time.
What you can calculate
The calculator covers the shapes and outputs most concrete projects need. Every result comes from the same dimensions, so you can compare bags against ready-mix without re-entering anything.
Volume
Cubic yards, cubic metres, and cubic feet from one set of measurements.
Bags
Counts for 50 lb, 60 lb, and 80 lb concrete mix, rounded up so you do not run short.
Cost
An optional material estimate based on the price per cubic yard you enter.
Shapes and units
Slabs, circles, footings, walls, curbs, and steps in feet, inches, metres, or centimetres.
How the calculator works
Every calculation starts with volume. A rectangular slab is length × width × thickness; a round footing is π × radius² × height; steps multiply run × rise × width by the number of steps. The calculator converts each dimension to feet, multiplies, then divides by 27 for cubic yards.
Bag counts use standard yields — about 0.60 cubic feet for an 80 lb bag, 0.45 for 60 lb, and 0.37 for 50 lb. Those are planning figures, not a guarantee. Always check the yield printed on the bag you buy. The waste slider applies your chosen allowance before the final numbers are shown.
Cost is optional. Enter a price per cubic yard and the calculator multiplies it by the adjusted volume. It does not add delivery, short-load, tax, or finishing costs, because those vary by supplier and location.
Who it is for
ConcreteCals is designed for anyone who needs a dependable cross-check before ordering material:
- DIY homeowners planning a patio, shed base, driveway apron, or fence post.
- Contractors checking a supplier quote or confirming a takeoff.
- Landscapers, deck builders, and remodelers estimating small pours.
- Students and apprentices learning how concrete volume and bag counts work.
You do not need an account, and you do not need to install anything. Open the calculator, enter your dimensions, and read the result.
How we approach accuracy
ConcreteCals uses standard geometry and widely published concrete densities. Results are estimates, not engineering advice. Bag yields vary by brand and mix, subgrade conditions change how much concrete a form takes, and suppliers round orders differently.
Where we round, we round in the direction that helps you avoid a short pour. Bag counts are rounded up; volume is shown to two decimal places. For structural work, always confirm the mix, reinforcement, and volume with a qualified professional and your ready-mix supplier.
Privacy by design
Your measurements are processed by JavaScript in your browser. They are not posted to a server, stored in an account, or tied to your identity. The only setting ConcreteCals remembers is your light or dark theme, kept in local storage on your device.
You can read the details in our Privacy Policy.
Help us improve
Found a bug, a confusing label, or a result that does not match your supplier? Tell us. Feedback is how the calculator gets better, and specific examples are especially useful.
Send a note through the Contact Us page, or email hello@concretecals.com.