Concrete Mix Calc

Free · No sign-up · Results as you type

Concrete Calculator

Enter the length, width and thickness of your pour — get cubic yards, bag counts and estimated cost instantly, right on this page.

ft
ft
in
$USD

Concrete needed

2.96 yd³

80.0 ft³

Estimated cost

$489

at $165 per yd³

Approx. weight

10,640 lb

≈ 5.3 tons

Bagged mix

134

80-lb bags

178

60-lb bags

267

40-lb bags

Before you order: add about 10% for uneven subgrade and spillage — that's 3.26 yd³ or 147 × 80-lb bags.

How to Use This Concrete Calculator

  1. Measure the length and width of your pour in feet.
  2. Enter the thickness in inches — 4 in. is standard for patios and walkways, 5–6 in. for driveways.
  3. Read the result as you type: cubic yards, bag counts, weight and estimated cost. Add about 10% before you order.

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What Is a Concrete Estimator?

A concrete estimator is any tool that predicts how much concrete a job needs before you buy it. This calculator estimates four things at once: volume in cubic yards, the number of 40, 60 or 80-lb bags that equals, the weight of the wet concrete, and what it should cost. It is the same math a contractor runs before calling the batch plant — you just see the answer on the spot instead of in an invoice.

Because the estimate updates as you type, you can compare scenarios in seconds: a 4-inch slab against a 6-inch one, bagged mix against ready-mix delivery, a slightly smaller footprint. Run the numbers before you order and you will never pay for a yard of concrete you don't need.

How Much Concrete Do I Need?

The quick answer: volume (ft³) = length (ft) × width (ft) × thickness (ft), then divide by 27 to get cubic yards. Thickness is usually measured in inches, so divide it by 12 first.

Example: a 12 × 20 ft patio at 4 inches thick is 12 × 20 × 0.333 = 80 ft³, which is 80 ÷ 27 ≈ 2.96 cubic yards — order about 3.3 yards with the 10% allowance. The calculators on this site run this math for every common project shape; for flat pours, concrete slab calculator does it in one step.

Frequently Asked Questions

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

45 bags. One 80-lb bag yields about 0.60 ft³ of mixed concrete and one cubic yard is 27 ft³, so 27 ÷ 0.60 = 45 bags. A 60-lb bag yields 0.45 ft³ (60 bags per yard) and a 40-lb bag yields 0.30 ft³ (90 bags per yard).

Does the estimated cost include delivery?

No — the default $165 per cubic yard is a typical delivered ready-mix price, but real prices vary by region and order size. Edit the price field to match your local quote. For small pours, bagged mix is usually cheaper because you avoid short-load delivery fees.

Should I order exactly what the calculator says?

No. Add about 10% to cover uneven subgrade, spillage and over-excavation, and remember most suppliers sell ready-mix in quarter-yard increments. The calculator shows the with-waste amount for you.

Is this concrete calculator free?

Yes. Every calculator on this site is free, runs entirely in your browser, requires no sign-up, and updates the result as you type.

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The plain answers behind the numbers — drying and curing times, real costs, and how-to walkthroughs.