MyYardCalc
Construction · Material planning

Concrete Slab Calculator

Estimate concrete for a flat slab using area and specified thickness. Calculate cubic yards, mixed-yield bags and your material purchase costs.

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Your project

US & metric

Example values are filled in. Replace them with your measurements.

ft
ft
sq ft

Add other measured sections without counting overlaps twice.

sq ft
in
%

An editable purchasing margin, not a measured compaction rate.

cu ft

Use the labeled volume of the product you plan to buy.

lb / cu yd

Optional. Enter the density of this product to estimate weight.

$
$ / cu yd
$

Enter 0 if included. Bulk cost remains blank until delivery is specified.

Enter your measurements

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The calculation

Volume = net area × depth × (1 + extra ÷ 100). Weight = volume × supplier density.

  • Enter your supplier’s bulk density to show weight. Volume alone cannot determine tons.
  • 10% extra is included once. Confirm supplier minimums and delivery increments.

Saved on this device

Only estimates you choose to save are stored here.

    Measure with a little context

    How to use this concrete slab calculator

    Use the slab’s specified thickness and measure formed dimensions. Thickened edges or separate footings should be calculated as additional pours.

    This is a material estimate. Slab thickness, reinforcement and ground preparation need the project’s design specifications.

    Volume = net area × depth × (1 + extra ÷ 100). Weight = volume × supplier density.

    A worked example

    With the example values shown below, the calculated result is 1.304 cu yd. These are demonstration inputs, not installation specifications.

    View the example measurements
    • Length / circle diameter: 12 ft
    • Width: 8 ft
    • Material depth: 4 in
    • Extra allowance: 10 %
    • Volume per bag: 0.6 cu ft

    From estimate to order

    Whole packages and pieces round up; measured lengths, areas and volumes keep full precision during calculation. Match the product dimensions and units to your quote, and check cuts, minimum orders and delivery before purchasing.

    Read our formulas, rounding rules and limitations →

    Concrete slab planning questions

    How much concrete does a 10 × 10 slab need?

    At an example thickness of 4 inches, 100 × 4 ÷ 324 equals 1.235 cubic yards before allowance. Add thickened edges or separate footings as additional pours. Use the thickness from the actual design; the example does not determine structural adequacy.

    Is the concrete slab cost a complete installation quote?

    No. It compares material quantities using the prices and delivery charge you enter. Excavation, forms, reinforcement, finishing, labor, taxes and supplier minimums are separate. A whole-job installation cost needs those project-specific items.

    How do I estimate a slab with a thickened edge?

    Calculate the main slab at its regular thickness, then calculate only the additional depth of the thickened edge as separate rectangular sections. Avoid counting the edge footprint twice at full depth. Footings, steps and other separate pours need their own dimensions and quantities from the design.

    Calculation notes updated . Formulas, sources and limitations.

    Keep your project moving.

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