12x12 Concrete Slab Cost Worksheet by Thickness

A 12 by 12 foot slab has 144 square feet of area and needs about 1.78 cubic yards at 4 inches before allowance. Use the approved thickness and base details, then price concrete, reinforcement, preparation, delivery and finish from local quotes; the dollar table is illustrative only.

What a 12x12 concrete slab costs installed

State the 12x12 slab area, thickness, base, reinforcement, finish and access in each quote.

Illustrative calculation inputs only. Replace every price with a current, scope-matched local quote.
Job type	Per sq ft	12x12 total
Basic 4 in, broom finish	6 to 9 dollars	about 870 to 1,300 dollars
4 in with wire mesh or rebar	8 to 12 dollars	about 1,150 to 1,730 dollars
6 in, reinforced, light grading	10 to 15 dollars	about 1,440 to 2,160 dollars
Decorative example scope	13 to 18 dollars	about 1,870 to 2,600 dollars

To price your own dimensions, finish and thickness, enter them in the concrete slab calculator and it returns yards, bags and an estimated cost.

Cost breakdown: concrete, labor, and site prep

The total splits into three buckets that move independently. Knowing each one helps you read a contractor quote and spot anything out of line.

Site preparation covers excavation, the gravel base and forms. On flat, clear ground this is minor, but sloped lots, poor soil or tree roots add hours and can swing the overall cost by several hundred dollars.

How much concrete for a 12x12 slab in cubic yards

A 12x12 slab at 4 inches needs about 1.96 cubic yards of concrete with a 10% waste allowance, or close to 1.78 yards before waste. The math is the footprint times the thickness in feet, divided by 27 to convert cubic feet to cubic yards.

Cubic feet = 12 x 12 x (4 ÷ 12) = 48 ft3Cubic yards = 48 ÷ 27 = 1.78, then +10% = 1.96

Thickness drives the volume, so a 6-inch pad uses about 50% more concrete, near 2.93 cubic yards with waste. Always round a ready-mix order up to the nearest quarter yard, because you cannot top up a pour once the truck leaves.

12x12 slab	Cubic yards (+10%)	Cubic meters	80 lb bags
4 inches	1.96	1.50	88
5 inches	2.44	1.87	110
6 inches	2.93	2.24	132

How thick should a 12x12 concrete slab be

Use the slab thickness, edge detail, reinforcement and support required by the approved design and local conditions. Area alone cannot select the section.

Changing an entered thickness from 4 to 6 inches increases concrete volume by 50%, but this arithmetic does not predict cracking or service life.

Confirm the required section before ordering.

A concrete finisher floating the surface of a freshly poured 12 by 12 foot backyard slab with a bull float

Do you need gravel and rebar under the slab

Use the subgrade and base detail specified for the project loads, soil, drainage and local conditions. Aggregate type, compacted depth, vapor control and acceptance requirements cannot be selected from the 12x12 footprint.

If the approved detail contains a 4-inch layer, 144 square feet times 4/12 feet divided by 27 equals 1.78 cubic yards of compacted geometric volume. Convert that to the purchase quantity with supplier data.

Apply current rates only to the specified slab area, section, base, reinforcement, finish and access.

DIY versus hiring a contractor for a 12x12 pad

Mixing 88 bags by hand is impractical for most people, so DIYers usually order ready-mix and focus their effort on the forms, base and finishing. A slab that size sets fast and you cannot pause a pour, so line up help before the truck arrives.

Hiring a pro folds in the gravel base, forms, reinforcement, pour, finish and cleanup, and a crew finishes a 12x12 pad in a day. If you want to compare a hand-poured estimate against a hired quote, the breakdown in the cost to pour a concrete slab walks through both paths by size.

By Calcnaut

Formula and declared-case checks run during the build; sources are listed for readers to review. Read our method and editorial policy.

Published 2026-06-19 Updated 2026-09-13

Illustrative worksheet, not a quote. These dollar figures are illustrative assumptions, not market data. Replace every rate with a current local quote for the stated scope: All monetary tables and examples on this page; replace rates with current, scope-matched local quotes.

Frequently asked questions

How much would it cost to have a 12x12 concrete slab poured?

The page illustrates $6 to $18 per square foot for different assumed scopes, producing about $870 to $2,600 for 144 square feet. Those figures are not market quotes. Replace the relevant input with a current bid stating thickness, base, reinforcement, concrete, finish, access and delivery.

How much would a 10x10 concrete pad cost?

A 10 by 10 pad is 100 square feet. Multiply that area by a current local installed quote for one defined thickness, base, reinforcement and finish. If using the page's illustrative $6 to $12 input only to test arithmetic, the result is $600 to $1,200.

Do I need gravel under a concrete slab?

Use the subgrade and base specified for the site, loads and local conditions. Some slabs require a compacted aggregate base or drainage layer, while an approved detail may differ. The calculator can quantify a known layer thickness but cannot select the base material or prove that it will prevent cracking.

How thick should a 12x12 concrete slab be?

Area alone cannot determine thickness. Use the slab section specified for the intended loads, soil support, concrete properties, joints and local requirements. Once thickness is established, enter it in the calculator; moving from 4 to 6 inches increases volume by 50%.

How many bags of concrete for a 12x12 slab?

A 12x12 slab at 4 inches takes about 88 bags of 80 lb mix, 117 bags of 60 lb, or 176 bags of 40 lb, including a 10% waste allowance. That is a lot of hand mixing, so most people order ready-mix for a pad this size.

Sources and references

These references and structured source records support the method and material data used on this page.

12x12 Concrete Slab Cost Worksheet

Key takeaways