Everyday MathFree

Concrete Yardage Calculator

Estimate concrete volume for slabs in cubic feet and cubic yards, and approximate how many 80 lb premixed bags to buy. Enter length, width, and thickness in feet and inches.

Enter Values

Length

Width

Depth

Result

Enter values above and click Calculate to see your result.

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Formula

Core Formula

V = L \times W \times \frac{D_{\text{in}}}{12} \quad \text{yd}^3 = \frac{V}{27}

How it works: The slab is treated as a box: length and width in feet, depth in inches converted to feet. Bags assume about 0.6 cubic feet yield per 80 lb bag, which is a common planning estimate (confirm on the bag).

Worked Example

Patio 12 ft by 10 ft, 4 inches thick:

1Step 1: Depth = 4 / 12 = 0.333 ft

2Step 2: Volume = 12 x 10 x 0.333 = 40 cu ft

3Step 3: Cubic yards = 40 / 27 = 1.48 cu yd

4Step 4: 80 lb bags = ceil(40 / 0.6) = 67 bags

Frequently Asked Questions

Why does bag count differ from the store calculator?

Bag yield varies by product and slump. This tool uses a typical 0.6 cubic feet per 80 lb bag for rough ordering. Always check the label on your mix.

Should I order extra concrete?

Short loads are costly to fix. Many crews order 5 to 10 percent extra for spillage and uneven subgrade.

Can I enter depth in feet?

This version expects depth in inches because thin slabs are usually measured in inches. Convert feet to inches first (for example 0.5 ft = 6 in).

Can I use this Concrete Yardage Calculator on my own web page?

You can. Look for the "Embed" button near the top of this calculator. It lets you pick a size, border style, and color palette, then gives you an iframe tag to paste into any webpage. The widget is responsive, loads fast, and costs nothing. More details at calculory.com/services/embed-calculators.

AI Assistant

Ask about this calculator

I can help you understand the concrete yardage calculator formula, interpret your results, and answer follow-up questions.

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