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Concrete yardage calculator

Enter the length, width, and thickness of the pour and a waste allowance, and the calculator returns the cubic yards to order. Running short mid-pour means a cold joint, so most crews add 5 to 10 percent. Confirm the final number and the mix with the ready-mix supplier.

Worked example

You are pouring a 40 ft × 30 ft slab at 4 in thick and want a 10% waste allowance.

  • Area40 ft × 30 ft
  • Thickness4 in
  • Waste10%
  1. Volume = length × width × thickness (in feet) = 40 × 30 × (4 ÷ 12) = 400 cu ft.
  2. Cubic yards = 400 ÷ 27 = 14.8 cu yd.
  3. Add 10% waste: 14.8 × 1.10 = 16.3 cu yd to order.

Order about 16.3 cu yd. Ordering short mid-pour risks a cold joint, so most crews round up to the next quarter-yard.

Change the numbers in the calculator above to run your own.

anvilfield.com/calculators/concrete-yardage-calculator · Free field calculators and FieldOS. A planning estimate, verify against the code, the manufacturer, and the engineer of record.

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Comparing your options?

PT slab vs rebar slabPost-tensioning buys longer spans, thinner sections, and fewer joints; rebar is simpler to build and cut into later.

Concrete yardage FAQ

What is a concrete mix design?

A concrete mix design is the approved set of proportions, cement, water, aggregate, and admixtures per cubic yard, chosen to hit a specified strength, durability, and workability at once. The ready-mix supplier proportions and submits it from the project spec, and the engineer approves it. The field crew protects those proportions rather than redesigning them.

What is the water-cement ratio?

The water-cement ratio is the mass of free water divided by the mass of cementitious material in the mix, written w/c or w/cm. It is the master variable: a lower ratio gives higher strength and lower permeability, a higher ratio gives weaker, more permeable concrete. Most structural mixes run between about 0.40 and 0.55.

Why can't you add water to concrete on site?

Adding water beyond the design raises the water-cement ratio above the approved maximum, which lowers strength and raises permeability even though the slump improves. The mix looks better going in and breaks low later. Only the plant-withheld design water may be added, once, within the w/c limit. Raise flow with a water reducer instead.

What is f'cr in concrete mix design?

f'cr is the required average strength the mix is proportioned to, set higher than the specified strength f'c. Because strength scatters batch to batch, targeting exactly f'c would fail acceptance half the time. ACI 318 sets the overdesign margin from the producer's standard deviation, so the normal scatter still passes the acceptance criteria.

How does exposure class set the maximum water-cement ratio?

ACI 318 sorts service conditions into freeze-thaw (F), sulfate (S), water (W), and corrosion (C) classes, and the strictest assigned class sets a code maximum w/cm and minimum f'c. Severe classes like F3 and C2 drive the w/cm to 0.40 and 5000 psi. Confirm the limits against the adopted edition.

More in the Mix design and water-cement ratio field guide.