Concrete Calculator Hub

Concrete Volume Calculator

Estimate concrete for slabs, pads, footings, round holes, and columns. Get cubic yards, cubic feet, cubic meters, bag count, waste, and material cost in one place.

Rectangular
Slabs, pads, floors, walkways, and simple footings.
Round
Post holes, columns, piers, and cylindrical pours.
Bags
Converts volume into whole concrete bags and cost.

Enter Measurements

Raw volume before waste

33.33 ft3 / 1.23 yd3

Results

Concrete Volume

1.358 yd³

36.6667 ft³ / 1.0383 m³

Bags Needed

62 bags

Rounded up to whole bags

Estimated Cost

$310.00

Based on bag price

Waste Factor

10%

Included in total volume

Formula

Rectangular slab or pad

Volume = length x width x thicknessVolume = 10 x 10 x 0.333

Waste and bags

Final volume = 33.3333 x (1 + 10%/100)Bags = ceil(final volume / 0.6)

Example Estimates

10 ft x 10 ft slab

Small patio, shed base, or pad at 4 inches thick.

Result: 1.358 yd3 / 36.6667 ft3 / 62 bags

20 ft x 12 ft driveway pad

Rectangular flatwork at 5 inches thick.

Result: 4.0741 yd3 / 110 ft3 / 184 bags

12 in round post hole

Round hole, 3 feet deep, with 10% waste.

Result: 0.096 yd3 / 2.5918 ft3 / 5 bags

When To Use This Page

  • Start here when you only know the shape and dimensions.
  • Use it for broad cubic yard estimates before choosing bags or ready-mix.
  • Move to a project-specific calculator when you need extra assumptions, such as stair landing volume or driveway waste.

Assumptions

  • Rectangular mode assumes a flat, uniform-thickness pour.
  • Round mode assumes a solid cylinder with no voids.
  • Bag yield and ready-mix ordering rules vary by product.
  • This is a material estimator, not structural advice.

Frequently Asked Questions

How do I calculate concrete volume?
For a rectangular pour, multiply length by width by thickness after converting all measurements to the same unit. For a round column or post hole, use pi times radius squared times height. Then add a waste factor before ordering material.
Should I use cubic yards or cubic feet?
In the United States, ready-mix concrete is usually ordered by cubic yard, while bagged concrete yield is usually printed in cubic feet. This calculator shows both so you can compare bagged concrete with delivery options.
How much waste should I add?
A 10% waste factor is a practical default for many small concrete projects. Use a higher percentage for uneven excavation, irregular forms, first-time DIY work, or pours where running short would be expensive.
Can this calculator estimate bags of concrete?
Yes. Choose the bag size and enter a bag price to estimate whole bags and material cost. Bag yield is approximate, so always check the yield printed on the product you plan to buy.
Is this calculator enough for structural work?
No. This page estimates material volume only. Structural slabs, footings, stairs, retaining walls, and code-regulated work may require a contractor, engineer, permit, or local building-code review.

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