Calcolatore calcestruzzo
Calcestruzzo per una soletta, una fondazione, un pilastro o un foro per palo — volume, sacchi e peso.
Scegli la forma che stai gettando, inserisci le misure, e questo dà il volume in metri cubi e iarde cube, i sacchi da comprare, e quanto consegnerebbe un'autobetoniera.
- Volume—
- In iarde cube—
- Con margine per lo sfrido—
- Sacchi da acquistare—
- Peso del getto—
- Come ordine di calcestruzzo preconfezionato—
- Costo approssimativo in sacchi—
Concrete Calculator: Estimate How Much Concrete You Need
Calculating the right amount of concrete before starting a project can save time, money, and unnecessary material waste. Whether you are building a concrete slab, driveway, patio, footing, foundation, or setting fence posts, knowing the exact concrete quantity required helps you order the correct amount.
A concrete calculator makes this process easier by estimating the volume of concrete needed based on your project's measurements. By entering the length, width, and depth of the area, you can quickly find the amount of concrete required in cubic feet, cubic yards, and concrete bags.
This tool is useful for homeowners, contractors, builders, and DIY enthusiasts who need a quick and reliable way to estimate concrete requirements before purchasing materials or ordering ready mix concrete.
What a concrete calculator does
A concrete calculator helps determine the amount of concrete required for different construction and home improvement projects. Instead of working through the measurements by hand, the calculator uses your project dimensions to estimate the total concrete volume.
To calculate your concrete requirements, enter:
- Length of the area
- Width of the area
- Depth or thickness of the concrete
- Diameter, for circular projects such as post holes or piers
The calculator gives you:
- Concrete volume in cubic feet
- Concrete volume in cubic yards
- Required bags of concrete mix
- Approximate concrete cost
That makes it easier to plan material purchases and avoid ordering too little or too much concrete.
How does a concrete calculator work?
A concrete calculator works by converting your project measurements into a volume. Since concrete is usually purchased by the cubic yard, the calculator first determines the total volume and then converts the result into the measurement suppliers use.
The basic calculation needs three measurements — length, width and depth:
Length × Width × Depth = Concrete Volume
Because concrete projects come in different shapes and sizes, the method changes with the structure. A rectangular slab, a circular footing and a cylindrical post hole each need a different formula to arrive at the correct quantity.
How to calculate concrete volume
Understanding the formula helps you sanity-check the result, even when a calculator is doing the arithmetic. Concrete volume is measured in cubic feet, cubic yards or cubic metres, and in construction it is commonly ordered in cubic yards.
Concrete volume formula
For a rectangular area:
Concrete Volume = Length × Width × Depth
Take a slab 20 feet long, 10 feet wide and 4 inches thick. First convert the depth into feet:
4 inches ÷ 12 = 0.33 feet
Then:
20 × 10 × 0.33 = 66 cubic feet
To convert cubic feet into cubic yards, divide by 27:
66 ÷ 27 = 2.44 cubic yards
The project would need roughly 2.44 cubic yards of concrete.
Cubic feet vs cubic yards of concrete
Ordering gets confusing because measurements appear in different units.
Cubic feet
A cubic foot is a volume one foot long, one foot wide and one foot deep. Small projects are sometimes worked out in cubic feet.
Cubic yards
A cubic yard is the standard measurement used by concrete suppliers. One cubic yard equals:
- 27 cubic feet
- 46,656 cubic inches
Ready mix companies sell by the cubic yard, which is why that figure matters on larger projects.
Concrete slab calculator
A slab calculation covers flat surfaces such as patios, garage floors, walkways, shed bases and basement floors.
Length and width
The surface area determines how much ground the concrete has to cover.
Slab thickness
Thickness matters more than people expect, because a thicker slab needs proportionally more concrete across the whole area. Common thicknesses:
- 4 inches for sidewalks and patios
- 5 to 6 inches for driveways
- More for heavy load areas
Slab volume
Length × Width × Thickness
Two slabs can look identical from above and still need very different amounts of concrete.
Concrete driveway calculator
Driveway calculations depend on the total length, the width, the thickness, and any extensions or curves.
Most standard residential driveways use a thickness between 4 and 6 inches. Driveways built for heavier vehicles may need more depth and reinforcement.
A driveway calculation gives you the total volume, the cubic yards needed and an approximate material cost. Measure the whole area before ordering, including the sections that are not a simple rectangle.
Concrete patio calculator
For an outdoor living space, seating area or garden extension, take into account the patio dimensions, the thickness, the shape and a waste allowance.
Most residential patios use a slab around 4 inches thick, though the right depth depends on use and on local practice.
Getting it right avoids running short mid-pour, paying for material you do not need, and delays on site.
Concrete footing calculator
Footings spread the weight of a structure and hold it stable. Common footing work includes house foundations, deck supports, columns, walls and structural posts.
Footings need length, width and depth. Because they carry structural load, accurate measurement matters more here than almost anywhere else on a job.
Concrete post hole calculator
Post holes are cylindrical, so they are calculated differently. The formula uses the hole diameter and the hole depth to find the volume of the space being filled.
The same approach covers fence posts, deck posts, sign supports, poles, concrete piers, sonotubes and round foundations.
Concrete bag calculator: how many bags do I need?
For smaller projects, concrete comes in bags. Common sizes are 40, 50, 60 and 80 pound bags.
The number of bags depends on the total volume, the bag size, and the coverage the manufacturer states. Different mixes cover different amounts, so check the label before buying.
For larger projects, ready mix is usually more practical than mixing bags one at a time.
Concrete cubic yard calculator
Most suppliers measure in cubic yards, and one cubic yard is 27 cubic feet.
Length × Width × Depth ÷ 27 = Cubic Yards
A project needing 81 cubic feet:
81 ÷ 27 = 3 cubic yards
Most suppliers suggest ordering slightly more than the calculated figure, because small measurement errors, uneven ground and waste all move the final number.
Concrete cost calculator
Concrete cost depends on the quantity, the price per yard, delivery fees, your location, the size of the project and any additional materials.
The average cost is normally worked out per cubic yard, but prices vary by supplier and by market. Beyond the concrete itself, budget for labour, excavation, reinforcement, formwork and finishing.
How much concrete do I need?
It depends on the size and type of the project, and you need accurate length, width and depth for all of them.
| Project type | Main measurements |
|---|---|
| Concrete slab | Length, width, thickness |
| Driveway | Length, width, depth |
| Patio | Area size and thickness |
| Footing | Length, width, depth |
| Post hole | Diameter and depth |
Concrete mix calculator: understanding the materials
A mix calculation estimates the ingredients when you are making concrete yourself rather than ordering ready mix. Concrete combines cement, sand, gravel or aggregate, and water, in proportions that depend on the strength required and the type of work.
Cemento
The binder. Mixed with water it forms a paste that holds the sand and aggregate together.
Sabbia
Fills the smaller gaps between aggregate particles and makes the mix easier to work.
Gravel and aggregate
Provides strength and stability, and makes up a large share of the volume.
Acqua
Activates the cement and drives the reaction that hardens the concrete. Too much water weakens the result; too little makes the mix unworkable.
Concrete mix ratio
A common traditional ratio is:
1 part cement : 2 parts sand : 3 parts aggregate
The right mix depends on the strength required, the conditions, the structure and the type of project. On professional work, follow local building standards and engineering advice.
What changes the amount of concrete you need
Slab thickness
Thickness is the single biggest factor. Going from 4 inches to 6 inches does not add a little material — it adds half as much again across the entire area.
Shape and design
Rectangles are easy. Curved patios, circular foundations, angled driveways and multiple connected sections are not. Breaking a complicated job into simple sections and adding the results is more accurate than trying to average it.
Ground conditions
Uneven ground takes more concrete, because the low spots still have to reach the finished thickness. Preparing the site properly keeps the estimate honest.
Sfrido
Most people order slightly more than the calculation to cover measurement errors, spillage, uneven surfaces and material lost during the pour. Most contractors build this in as a matter of course.
Ready mix concrete vs bagged concrete
Ready mix
Mixed by the supplier and delivered to site. Faster, consistent, less manual work, and the sensible choice on anything large. Sold by the cubic yard.
Bagged mix
Convenient for DIY work, easy to store, and well suited to repairs and small structures. Mixing enough bags for a large pour, though, takes a long time.
Common concrete calculation mistakes
Using square feet instead of cubic feet
Square feet measure area; concrete is bought by volume. Without a thickness, the number is not an estimate of anything.
Forgetting to convert measurements
Everything has to be in the same units before you multiply. Inches become feet; feet become yards where needed. A missed conversion changes the answer by a factor, not by a rounding error.
Ignoring thickness
A driveway and a patio with the same surface area need different amounts of concrete when their depths differ.
Ordering exactly the calculated amount
A calculator gives a clean estimate; a building site does not behave cleanly. A small extra covers uneven excavation, spillage and minor differences in measurement.
Getting an accurate estimate
Measure carefully
Take the length, width and depth more than once. Two matching readings are worth more than one confident one.
Use consistent units
Pick one system — feet and inches, yards, or metric — and convert everything before you calculate.
Divide complex areas
Work out each section separately and add them up: the main patio, the walkway, the steps, any extensions.
Confirm what the supplier needs
Check the concrete types available, the delivery fees, any minimum cubic yard order, and the waste allowance they recommend.
Worked examples
Example 1: a concrete slab
15 feet long, 10 feet wide, 4 inches thick.
4 ÷ 12 = 0.33 feet
15 × 10 × 0.33 = 49.5 cubic feet
49.5 ÷ 27 = about 1.83 cubic yards
Example 2: a concrete footing
20 feet long, 1 foot wide, 1 foot deep.
20 × 1 × 1 = 20 cubic feet
20 ÷ 27 = about 0.74 cubic yards