Español

Concrete calculator

Choose what you’re pouring and type the sizes. Yards, bags and cost update as you type, next to a drawing of the pour to check your numbers against.

Figures checked October 1, 2026

%

Covers spillage, uneven ground and forms that bow. 5–10% is usual.

Prices (optional)
$
$ / yd³

Defaults: $6.47 per 80 lb bag (one store, Oct 2026); $180/yd³ ready-mix (2025 US average).

Drawn to scale from your sizes.
1.36 cubic yards

to order, including 10% extra · 36.7 ft³ · 1.04 m³

Volume before extra
1.23 yd³ (33.3 ft³)
80 lb bags
62 bags
or 40 lb bags
123
or 50 lb bags
98
or 60 lb bags
82
Weight in place
≈ 4,833 lb (2.4 tons)

Cost of materials

62 × 80 lb bags
$401
Ready-mix, 1.36 yd³
$244

Ready-mix prices exclude delivery and short-load fees, which suppliers add to small orders. Ask for a quote before you compare.

That’s more than 60 bags of hand mixing. Above roughly a cubic yard, compare a ready-mix quote — see bags vs ready-mix.

The formula, a worked example and every source are on the slab calculator page.

All calculators

Ten tools that share one method: published yields, assumptions you can see, and a source for every number.

Volume & bags

Footings & posts

Steel & masonry

Pour day

How the numbers are made

Every result can be checked by hand.

  1. Published yields, not guesses

    Bag counts use the manufacturers’ own yield figures — an 80 lb bag of Quikrete or Sakrete makes 0.60 cubic feet — and the formulas are tested against their published examples.

  2. Assumptions on the page

    Overage, density, lap lengths and prices sit next to every result and can be changed. Nothing is hidden in the arithmetic.

  3. Sources you can click

    Each number links to the data sheet, code section or association guide it came from, with the date it was last checked. See every source.

Guides

The reasoning behind the calculators.