Concrete Calculator & Cost Estimator
Use this concrete calculator and concrete cost estimator to calculate cubic yards, cubic feet, bag count, and ready-mix cost for slabs, patios, driveways, footings, sonotubes, walls, and stairs. It is designed for U.S. measurements and helps you estimate how much concrete you need before you order.
- Concrete calculator
- Concrete cost estimator
- Concrete slab calculator
- Concrete bags calculator
- Sonotube calculator
How to Calculate Concrete
Concrete is usually measured by volume. For most projects, the first step is to calculate the total cubic feet, then convert that result into cubic yards because ready-mix concrete is commonly ordered by the cubic yard.
For a slab, patio, driveway, sidewalk, or footing, use length × width × depth. If your measurements are in feet, the result gives cubic feet. Divide cubic feet by 27 to get cubic yards.
For a sonotube or round column, use the cylinder formula based on radius and height. For bagged concrete, divide the total cubic feet by the yield per bag to estimate how many bags you need.
It is also smart to add extra concrete for waste. Small variations in grade, formwork, and spillage can increase the amount you actually need on site.
Concrete formulas
- Cubic feet = Length × Width × Depth
- Cubic yards = Cubic feet ÷ 27
- Sonotube volume = \( \pi \times r^2 \times h \)
- Bag count = Total cubic feet ÷ bag yield
- Concrete cost = Ordered yards × price per yard + extra fees
Concrete Cost Estimator
A concrete cost estimator helps you move beyond volume and understand the likely project cost before you place an order. For many homeowners and contractors, cost is the most important part of the concrete planning process.
The cost of concrete usually starts with the price per cubic yard for ready-mix concrete. After that, the final total can increase because of delivery charges, short-load fees, additives, fiber, pump rental, and waste.
Standard ready-mix concrete often falls in a common market range for basic residential strengths, but local pricing can vary by region, supplier, travel distance, order size, and PSI level. Smaller orders often have a higher cost per yard because short-load charges can raise the total quickly.
That is why a practical concrete cost estimator should let you enter:
- Concrete price per cubic yard
- Waste percentage
- Delivery fee
- Short-load fee
- Optional additive cost
Concrete Slab Calculator
A concrete slab calculator is useful for patios, driveways, garage floors, shed pads, sidewalks, and small residential foundations. These projects are usually measured with a simple rectangular volume formula.
The most important input for a slab is thickness. A 10 × 10 slab at 4 inches thick needs much less concrete than a 10 × 10 slab at 6 inches thick, which is why thickness should always be entered carefully.
If you are pouring a driveway or patio, it also helps to add a waste factor so your final order better matches actual field conditions.
Concrete Footing Calculator
A concrete footing calculator is used for foundation footings, strip footings, and other structural base pours where width and depth are often measured in inches while the total length is measured in feet.
For a footing, calculate the length, width, and depth, convert them into the same unit, and then convert the result into cubic yards if you plan to order ready-mix concrete.
Footings are one of the most important areas to measure correctly because underestimating the volume can delay a pour and increase the total job cost.
Sonotube Calculator
A sonotube calculator helps estimate concrete for deck footings, pergola posts, fence posts, and round concrete columns. This type of project needs a cylinder volume formula instead of a rectangular slab formula.
To calculate concrete for a sonotube, enter the tube diameter, the height or depth, and the number of tubes. The calculator then converts that shape into cubic feet and cubic yards and can also show how many concrete bags are needed.
This is especially helpful for small post and footing jobs where bagged concrete may be more practical than ordering a ready-mix truck.
Concrete Bags Calculator
A concrete bags calculator is useful when you are working on a small pour and want to know how many bags of concrete mix to buy instead of ordering ready-mix.
Common bag sizes include 40 lb, 50 lb, 60 lb, and 80 lb. Each bag produces a different amount of cured concrete, so the bag count depends on both the project volume and the selected bag size.
For very small pours, bags can be the easier option because there is no delivery charge and no minimum order. For larger pours, ready-mix is often the better option in both time and total material cost.
Ready-Mix Concrete Cost Per Yard
Ready-mix concrete cost per yard is one of the most important numbers in a concrete estimate. The final cost per yard can change based on PSI strength, travel distance, order size, local market pricing, and whether the order is below the supplier’s minimum load.
When the order is small, short-load fees can increase the real cost per yard significantly. That is why it is helpful to compare the total delivered price, not just the advertised base price per cubic yard.
A realistic concrete cost estimate should look at the full order total and not just the raw yardage.
Common Concrete Projects
Concrete is used in many everyday residential and light construction projects. A useful calculator should help you estimate the amount of concrete needed for the shape and type of job you are planning.
Slabs
Concrete slabs are common for patios, garage floors, shed pads, sidewalks, and driveways.
Footings
Footings are used to support foundations, walls, and structural elements that need a solid base.
Sonotubes
Sonotubes are often used for deck posts, pergolas, fences, and round support columns.
Walls and Stairs
Concrete walls and stairs need shape-specific measurements so the total pour is estimated correctly.
Why Waste Factor Matters in a Concrete Estimate
Concrete calculations on paper may be exact, but real projects usually need a little extra material. Waste factor covers small overages caused by uneven grade, spillage, form variations, and jobsite conditions.
Adding a waste percentage can help reduce the risk of running short during a pour. That is especially important for slabs, footings, and other continuous pours where stopping to reorder can create delays and extra expense.
Ready-Mix vs Bagged Concrete
Choosing between ready-mix and bagged concrete depends mainly on project size. Bags can work well for post holes, small footings, repairs, and isolated pours. Ready-mix is usually the better choice for slabs, patios, sidewalks, and larger foundation work.
Bagged concrete is easy to buy in small quantities, but the cost per cubic yard is usually much higher than ready-mix. Ready-mix saves time on larger pours, but delivery fees and short-load charges can make it less economical for very small jobs.
For ready-mix concrete information in the U.S., visit CEMEX USA Ready Mix Concrete.
Concrete Calculator FAQ
These answers cover the most common questions people have when estimating concrete volume, bag count, and cost.
How much concrete do I need?
How many cubic yards of concrete do I need?
How many 80 lb bags of concrete make a yard?
What is a concrete cost estimator?
How do I calculate concrete for a sonotube?
Should I add extra concrete for waste?
Is ready-mix cheaper than bagged concrete?
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