Concrete Calculator

Estimate concrete for slabs, footings, and thin self-leveling or floor-leveler pours by area and thickness — with adjustable bag yield and cost.

Concrete Calculator

Estimate how much you need — and the cost.

Area shape
You need
1.23 cubic yards
≈ 56 bags
Also equals
  • cubic feet 33.33
  • cubic meters 0.944
  • tons (US) 2.5
  • tonnes 2.27

Self-leveling concrete and floor leveler calculator

Self-leveling underlayment is a thin, product-specific pour. Enter the floor dimensions and average fill thickness above, then replace the default concrete Bag yield with the yield or coverage stated by the manufacturer. For LevelQuik RS, the published coverage is equivalent to roughly 0.49 cu ft per 50 lb bag.

Use the calculated volume and adjusted bag count for planning. The tons estimate uses ordinary concrete density, so it is not the purchasing figure for a self-leveling product. Deep low spots should be measured separately because one average thickness can understate the material needed.

1/8 in thickness
46–48 sq ft per 50 lb bag
1/4 in thickness
23–24 sq ft per 50 lb bag
1/2 in thickness
11.5–12 sq ft per 50 lb bag
1 in thickness
5.75–6 sq ft per 50 lb bag

Source: CUSTOM LevelQuik RS technical data sheet

Quick coverage reference

1 cubic yard = 27 cu ft, covering about 81 sq ft at 4 in / 54 sq ft at 6 in; an 80 lb pre-mix bag yields about 0.6 cu ft (about 45 bags per cubic yard).

How it's calculated

  • Standard concrete density is about 150 lb/cu ft (= 4050 lb/cu yd); it varies slightly with mix and aggregate.
  • Sidewalks / slabs: 4 in; driveways or load-bearing areas: 5–6 in; footings per project spec.

Source: inchcalculator.com/concrete-calculator/ (density 150 lb/cu ft, 80 lb bag = 0.6 cu ft cross-checked); custombuildingproducts.com/TDS/TDS-108.pdf (LevelQuik RS coverage by thickness)

Common concrete uses

for Patios for Driveways for Sidewalks for Footings

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How much concrete do I need?

Concrete is ordered by the cubic yard for ready-mix, or mixed from bags for small jobs. The volume you need is the area of the slab multiplied by its thickness.

Use cubic yards = area (sq ft) × thickness (in) ÷ 324. One cubic yard fills about 81 sq ft at the typical 4-inch slab thickness. If you're mixing from bags, an 80 lb bag yields about 0.6 cu ft, so it takes roughly 45 bags to make one cubic yard — the calculator shows the bag count so you can decide between bags and ready-mix.

How to measure for concrete

Measure the slab

Length × width in feet. For footings or odd shapes, split into rectangles and total the volume.

Set the thickness

4 inches for patios, walkways, and shed bases; 5–6 inches for driveways and anything bearing vehicle loads.

Read yards and bags

Get cubic yards plus the number of 80 lb bags, so you can compare mixing it yourself against ordering ready-mix.

Add 5–10% extra

Uneven sub-grade and spillage eat into volume. Order a little over so you do not stop a pour halfway.

Concrete thickness & buying tips

Bags vs. ready-mix

Bagged mix suits small jobs up to roughly half a yard. Beyond that, bagging gets expensive and slow — ready-mix delivery is better.

Thickness by load

4 inches handles foot traffic and patios; step up to 5–6 inches wherever vehicles will park or drive.

Don't run short mid-pour

A cold joint forms if a pour is interrupted. Always order a margin over the exact figure so the slab goes in continuously.

Concrete calculator FAQ

How many 80 lb bags of concrete are in a cubic yard?

About 45 bags, since each 80 lb bag yields roughly 0.6 cubic feet and a cubic yard is 27 cubic feet. (60 lb bags ≈ 60 per yard.)

How much does a yard of concrete cover?

One cubic yard covers about 81 sq ft at 4 inches thick, 65 sq ft at 5 inches, or 54 sq ft at 6 inches.

How thick should a concrete slab be?

4 inches is standard for patios and walkways; use 5–6 inches for driveways or anything carrying vehicle weight.

When should I order ready-mix instead of bags?

Once you need more than about half a cubic yard. Beyond that, bags become costly and hard to mix fast enough.

How much does a cubic yard of concrete weigh?

About 4,050 lb (roughly 2 tons), based on standard concrete density of 150 lb per cubic foot.