Concrete Countertop Calculator
Calculate the exact number of bags needed to pour a custom countertop, plus estimate its total finished weight.
Countertop Dimensions
Concrete Required
For estimation purposes only. Verify structural calculations with a licensed engineer.
Calculate Concrete for Countertops
Pouring custom concrete countertops is an incredible way to upgrade a kitchen or outdoor BBQ island on a budget. However, because you are pouring the slab into highly customized melamine molds, estimating your materials can be difficult.
Running out of concrete halfway through a countertop pour will ruin the entire piece, as the resulting cold joint will be highly visible on the finished surface. Our concrete countertop calculator ensures you buy enough specialty countertop mix to fill your forms in a single, continuous pour.
Bags of Concrete for Countertop
When working with countertops, you don't order from a ready-mix truck. Instead, you purchase high-strength countertop bag mixes (which have finer aggregates than standard concrete to allow for a smooth polished finish).
To determine how much concrete for a countertop you need, measure your forms and calculate the cubic volume.
Length (in) Width (in) Thickness (in) = Cubic Inches
Cubic Inches 1728 = Total Cubic Feet
Total Cubic Feet 0.60 = Number of 80lb Bags Needed
Always round up to the nearest full bag. For complex kitchen layouts (like L-shapes), calculate each rectangular section separately and add the total bag counts together.
Concrete Countertop Weight Calculator
The most overlooked aspect of DIY concrete countertops is the sheer weight of the finished slab. Standard plywood kitchen cabinets are strong, but they have limits.
Our tool automatically functions as a concrete countertop weight calculator. A standard concrete mix weighs approximately 145 to 150 pounds per cubic foot. Therefore, a standard countertop poured at 2 inches thick will weigh approximately 24 pounds per square foot.
If your calculator indicates your island will weigh over 500 pounds, you may need to reinforce the interior of your cabinet bases with 2x4 framing to ensure they don't collapse under the massive weight of the concrete.