Concrete Calculator
Convert slab or project dimensions into cubic feet and cubic yards. Add an explicit extra percentage and, if you are using bagged mix, enter the exact yield printed for that product.
Compare two product options using your calculated requirement
Compare two bagged-mix options with the same calculated concrete volume. Enter each bag's mixed yield and current price to see whole-bag quantity, excess mixed volume and estimated material total.
Mixed concrete volume to cover: Run or update the calculator above.
This comparison uses only the coverage/yield and price values you enter. It does not rank brands, fetch retailer data, include tax or delivery, or replace product specifications.
Continue your project estimate
Estimate concrete project cost →Concrete volume formula
For a worked slab example and the cubic-foot to cubic-yard conversion, see How Much Concrete Do I Need?.
For a rectangular slab or section, multiply length by width by thickness after converting thickness from inches to feet. Divide cubic feet by 27 to convert to cubic yards.
cubic feet = length ft × width ft × (thickness in ÷ 12)
cubic yards = cubic feet ÷ 27
Ready-mix yards and bagged concrete are different purchase models
Ready-mix is commonly planned by cubic yard. Bagged concrete is sold by package, and the actual mixed yield per bag varies by product and package size. The calculator therefore never hides a universal bags-per-yard assumption.
If you want a bag count, enter the product yield in cubic feet from the bag or manufacturer data. The result rounds upward to a whole bag.
Use separate sections for non-rectangular projects
Driveways, footings, pads and slabs often contain areas with different thicknesses or shapes. Calculate each simple section separately and add the resulting volumes. This is more transparent than forcing a complex project into one average thickness.
Quantity first, cost second
This page is intentionally a quantity calculator. Once the required cubic yards are known, use the Concrete Cost Calculator to apply your supplier price, labor rate and project-specific fixed costs. Keeping quantity and cost as separate intents avoids mixing geometry with local pricing assumptions.
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Concrete Cost Calculator · Concrete Driveway Cost Calculator · Paver Calculator · Gravel Calculator
Compare a uniform slab with a thickened edge
Imagine a 10 × 12 ft rectangular pad with a 4-inch nominal thickness. Its uniform slab volume is 120 × (4 ÷ 12) = 40 cubic feet, or about 1.48 cubic yards. Now suppose a project plan specifies an additional 12-inch-wide strip, 12 feet long, with 4 extra inches of thickness beneath the normal slab depth. The additional edge volume is 12 ft × 1 ft × (4 ÷ 12) ft = 4 cubic feet, bringing the combined geometric volume to 44 cubic feet, or about 1.63 cubic yards.
Only add the depth beyond the slab's base thickness in the edge section; counting the entire thickened strip again would double-count the standard slab. This is a quantity illustration, not a foundation design. The correct footing geometry, reinforcement and site requirements must come from the approved plan.
Concrete order: bags versus ready mix
Follow a complete same-volume comparison with whole bag rounding, a ready-mix order increment and a delivery charge. The costs are illustrative, so substitute actual supplier prices.
Setting and curing are not quantities
Read concrete setting versus curing to understand why visible hardness does not establish safe loading or strength; this calculator determines volume only.
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