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Concrete Calculator

Use this concrete calculator for slabs, patios, footings, and pads by entering length, width, depth, waste, and price per cubic yard or cubic meter.

Last reviewed June 6, 2026Source note includedFree tool

Live calculator

Concrete

Concrete to order1.63 yd³

Includes 10% extra; 1.63 yd³ / 1.25 m³.

80 lb bags74

Approximate bag count using about 0.6 cubic feet per 80 lb bag.

Estimated concrete cost$260.74

yd³ multiplied by price per cubic yard.

Volume breakdown

Concrete is usually ordered in cubic yards.

MeasureAmount
Cubic feet40 ft³
Base cubic yards1.48 yd³
Base cubic meters1.13 m³
Order amount1.63 yd³ / 1.25 m³

Material estimates need field measurements and a waste allowance. Supplier coverage, cuts, breakage, compaction, and local installation requirements can change the order quantity.

Quick answer

Concrete Calculator: what it calculates

Concrete Calculator calculates concrete volume from feet or meters, length, width, depth, waste percent, and price per volume. The visible formula is Concrete volume = length x width x depth after converting all dimensions to one base unit.

ResultConcrete volume
InputsFeet or meters, Length, Width, Depth, Waste percent, Price per volume
FormulaConcrete volume formula

Formula

Concrete volume formula

Concrete volume = length x width x depth after converting all dimensions to one base unit

Feet mode uses inches and cubic yards; meters mode uses centimeters and cubic meters.

How to use

Steps

  1. Choose feet or meters for the project measurements.
  2. Enter the concrete area's length, width, and depth.
  3. Add waste percent for uneven forms, spillage, and ordering buffer.
  4. Review cubic yards, cubic meters, bag estimate, and material cost.

Example

Sample calculation

12 ft x 10 ft x 4 in1.48 yd³ before waste
Metric equivalent3.66 m x 3.05 m x 10.16 cm
With 10% waste1.63 yd³ / 1.25 m³
80 lb bagsAbout 74

Calculator use

Best for

  • Estimating cubic yards for slabs, patios, footings, pads, walkways, and small pours.
  • Checking ready-mix volume before calling a supplier or comparing bagged concrete.
  • Estimating 80 lb bags for small jobs where a truck delivery would be too much.
  • Adding waste for uneven forms, spillage, over-excavation, and field adjustments.

Before relying on it

Check first

  • Using inches, feet, and yards inconsistently across length, width, and depth.
  • Ordering exactly the calculated volume with no waste allowance for real jobsite conditions.
  • Using the result for structural design, load-bearing engineering, permits, or code compliance.
  • Forgetting that bag yield, slump, reinforcement, subbase, and form accuracy can change the real quantity.

Details

What to know before using the result

These notes make the assumptions explicit, especially where the same search query can mean slightly different things.

Unit mathKeep dimensions aligned

The calculator supports feet/inches or meters/centimeters and converts both systems to the same volume base before estimating.

Cubic yards27 cubic feet per yard

Concrete is commonly ordered by cubic yard, so cubic feet are divided by 27 after volume is calculated.

Bag count80 lb bag yield estimate

The bag estimate uses about 0.6 cubic feet per 80 lb bag and rounds up. Check the specific product label before buying.

Source notes

References used for this calculator

QUIKRETEProvides concrete calculator guidance and bag estimates for common concrete mixes.

Benchmarks

How to read the result

The calculator is a decision aid, not a fixed rule. Use the output to compare scenarios and document your assumptions. Benchmark ranges are broad planning heuristics unless this page names a specific source for the range.

2 in: Light overlay.

Usually too thin for structural slabs unless specified by a pro.

4 in: Common slab.

Often used for patios and walkways, depending on soil and load.

6 in+: Heavier use.

Often considered for driveways, pads, or heavier loads.

Calculator accuracy

Methodology and assumptions

The formula, inputs, example, and limitations are shown so the result is checkable, not just a number in a box.

Formula

Concrete volume = length x width x depth after converting all dimensions to one base unit

Inputs used

Feet or meters, Length, Width, Depth, Waste percent, Price per volume

Limitations

Home-material calculators estimate quantity and cost from visible dimensions and coverage assumptions. They do not replace field measurement, installer guidance, structural design, permits, or code review.

Last reviewed

June 6, 2026

Cite this page

Toolkit Shelf. Concrete Calculator. Last reviewed June 6, 2026. https://toolkitshelf.com/tools/concrete-calculator

FAQ

Common questions

How do I calculate concrete yards?

Multiply length by width by depth in feet to get cubic feet, then divide by 27 to convert to cubic yards.

How many 80 lb bags are in a cubic yard?

An 80 lb bag often yields about 0.6 cubic feet, so one cubic yard takes about 45 bags.

Should I add extra concrete?

Many projects add 5% to 10% extra for waste, uneven subgrade, and measurement differences.

Does this calculate reinforcement or permits?

No. It estimates concrete volume, bag count, and material cost. Reinforcement, subbase, drainage, permits, and structural design need separate planning.

Can I use this for a driveway or structural slab?

Use it only for a rough volume estimate. Driveways, load-bearing slabs, and code-sensitive work should be checked by a qualified contractor or engineer.

Why should I add a material buffer?

Cuts, waste, damaged pieces, uneven surfaces, pattern matching, delivery limits, and field measurements can all make the exact calculated amount too low.