Concrete Calculator
Use this concrete calculator to find the amount you need for concrete slabs, walls, footers, columns, steps, curbs and gutters.
Calculate Volume of Round Slab
Enter the measurements of your planned concrete structure in US units like inches or feet, or metric units like centimeters or meters. The calculator tells you the cubic yards or volume of concrete needed for your structure or project.
You can also enter the unit price to see the total volume and cost of the concrete in price per cubic foot, price per cubic yard or price per cubic meter.
Example Project: Filling Round Concrete Tubes
You have 50 round concrete form tubes (like sonotubes) that you need to fill with ready mix. Each tube is 4 feet high and has a 10 inch diameter. Using the calculator:
- Choose Round Column (or Round Slab)
- Enter Height: 4 ft (or 48 in)
- Enter Diameter: 10 in
- Click Calculate. You need 0.08 cubic yards of ready mix for each of your concrete tubes.
- Since you have to fill 50 tubes multiply 0.08 × 50 = 4 total cubic yards of concrete. You can also change the Quantity in the calculator to 50 and click Calculate to see the total volume of concrete you need as 4 cu yd.
Note that this calculation gives the volume inside the tubes only. It does not include any extra concrete for overflow or loss at the bottom of your tubes. You can add 10-15% extra to account for spillage or other loss.
What is Concrete?
Concrete is a composite material made from a mixture of cement, water, and aggregates (sand, gravel, or stone). When mixed, the water and cement combine into a mixture that binds the sand and gravel into a dense structure which hardens like a rock.
Use a Concrete Calculator to Estimate Common Projects
A concrete calculator helps you quickly estimate how much concrete you need. Using a concrete calculator can help reduce waste, support accurate budgeting, simplify material estimates, and avoid errors that lead to delays and additional expenses.
While concrete is one of the most widely used construction materials, it has low tensile strength. This means it can crack when used in designs that involve heavy pulling or hanging without proper reinforcement.
| Residential and Outdoor | Foundations and Structural | Commercial, Site and Utility |
|---|---|---|
| Patios, sidewalks and driveways (slabs on grade) | Footings (continuous or strip) | Warehouse/shop slabs and machine pads |
| Garage, basement, shed, RV or hot-tub pads | Isolated pad footings and pier pads | Dock aprons and loading ramps |
| Stairs or steps | Grade beams | Light-pole, sign bases and bollards |
| Curbs and gutters | Stem walls and poured foundation walls | Equipment pads (AC units, generators or tanks) |
| Ramps (access/garage) | Monolithic slabs or turned down edges | Drainage channels and trenches |
| Fence, deck or pergola posts (Sonotubes) | Square or round columns | |
| Raised beds, planters or benches (cast concrete) | Retaining walls (cast-in-place or ICF) |
Recommended Thickness Guide
Always follow local building codes and engineering requirements. Values below are common starting points for planning and estimating.
| Project Type | Typical Thickness | Notes |
|---|---|---|
| Sidewalk or walkway | 4 in (100 mm) | Often with light reinforcement or fiber |
| Patio or terrace | 4 in (100 mm) | Use compacted base; consider 4–5 in for heavy grills/fire features |
| Driveway (passenger cars) | 4–5 in (100-125 mm) | Go to 5–6 in for frequent trucks/SUVs |
| Garage slab | 4–5 in (100-125 mm) | Thicken at edges or use turned-down perimeter where specified |
| Hot-tub or spa pad | 6 in (150 mm) | Confirm load with manufacturer; add reinforcement as specified |
| Shed or small outbuilding pad | 4 in (100 mm) | Consider thickened edge or piers for heavier sheds |
| Stairs or steps (treads) | 3–4 in tread thickness | Volume depends on Total Run × Width × Riser Count |
| Footings (strip, continuous) | Varies (e.g., 8–12 in deep) | Width and depth are code/soil dependent—always confirm local building code |
Tips for Accurate Estimates
Planning a new or replacement concrete structure or slab is a complex process involving measurements of area, overall size, and potential pitch. Consider these points as you plan your concrete order.
- Irregular shapes: Break the area into simpler shapes (rectangles/circles/trapezoids) and add the totals
- Sloped slabs: Use Average Thickness = (min thickness + max thickness) ÷ 2
- Overage: Add 5–10% for waste, spillage, and uneven subgrade
- Unit consistency: Keep all inputs in the same system (US or metric) for accuracy
- Reinforcement and mix: Rebar, wire mesh, fibers and mix design do not change volume, but they affect performance—follow specs
Concrete Volume Formulas and Forms
Square Slab
Calculate concrete volume of a square slab
Measure in feet:
Volume in Cubic Feet (ft3) = Width × Length × Depth
Volume in Cubic Yards (yd3) = Volume in Cubic Feet (ft3) ÷ 27
Volume in Cubic Meters (m3) = Volume in Cubic Feet (ft3) × 0.0283
Round Slab
Calculate concrete volume of a round slab
Measure in feet:
Area of the Circle (ft2) = Pi × (Diameter ÷ 2)2
Volume in Cubic Feet (ft3) = Depth × Area
Volume in Cubic Yards (yd3) = Volume in Cubic Feet (ft3) ÷ 27
Volume in Cubic Meters (m3) = Volume in Cubic Feet (ft3) × 0.0283
Pi = 3.14
Wall
Calculate concrete volume of a wall
Measure in feet:
Volume in Cubic Feet (ft3) = Thickness × Length × Height
Volume in Cubic Yards (yd3) = Volume in Cubic Feet (ft3) ÷ 27
Volume in Cubic Meters (m3) = Volume in Cubic Feet (ft3) × 0.0283
Footer
Calculate concrete volume of a footer
Measure in feet:
Volume in Cubic Feet (ft3) = Width × Length × Depth
Volume in Cubic Yards (yd3) = Volume in Cubic Feet (ft3) ÷ 27
Volume in Cubic Meters (m3) = Volume in Cubic Feet (ft3) × 0.0283
Square Column
Calculate concrete volume of a square column
Measure in feet:
Volume in Cubic Feet (ft3) = Width × Length × Height
Volume in Cubic Yards (yd3) = Volume in Cubic Feet (ft3) ÷ 27
Volume in Cubic Meters (m3) = Volume in Cubic Feet (ft3) × 0.0283
Round Column
Calculate concrete volume of a round column
Measure in feet:
Area of the Circle (ft2) = Pi × (Diameter ÷ 2)2
Volume in Cubic Feet (ft3) = Height × Area
Volume in Cubic Yards (yd3) = Volume in Cubic Feet (ft3) ÷ 27
Volume in Cubic Meters (m3) = Volume in Cubic Feet (ft3) × 0.0283
Pi = 3.14
Steps
Calculate concrete volume of steps
Measure in feet:
Number of Steps is the total number of steps including the platform.
Calculate the volume in sections from the ground to the top of each section.
Think of the platform and each step as individual sections.
Volume in Cubic Feet Below Platform Surface =
Platform Depth × (Rise Height × Number of Steps) × Width
Counting steps starting at the bottom step and not including the platform there are Step Number 1, Step Number 2, Step Number 3, etc.
Volume in Cubic Feet Below Each Step =
Run Depth × (Rise Height × Step Number) × Width
Total up the step volumes then the total concrete you need is
Volume in Cubic Feet = Volume in Cubic Feet Below Platform + Volume in Cubic Feet Below Steps
Volume in Cubic Yards (yd3) = Volume in Cubic Feet (ft3) ÷ 27
Volume in Cubic Meters (m3) = Volume in Cubic Feet (ft3) × 0.0283
Curbs and Gutters
Calculate concrete volume of curbs and gutters
Measure in feet:
Calculate the volume in sections from the ground to the top of each section. The Curb and Gutter are each a section.
Volume in Cubic Feet Below Curb =
Curb Depth × (Curb Height + Flag Thickness) × Length
Volume in Cubic Feet Below Gutter =
Gutter Width × Flag Thickness × Length
Volume in Cubic Feet = Volume in Cubic Feet Below Curb + Volume in Cubic Feet Below Gutter
Volume in Cubic Yards (yd3) = Volume in Cubic Feet (ft3) ÷ 27
Volume in Cubic Meters (m3) = Volume in Cubic Feet (ft3) × 0.0283
Frequently Asked Questions
How many bags are in one cubic yard of concrete?
About 45 bags (80-lb), 60 bags (60-lb) or 90 bags (40-lb). Yields vary by brand so always be sure to check the bag.
How much does a cubic yard of concrete weigh?
Roughly 3,700-4,100 lb (about 2 tons) depending on mix and moisture.
How much extra concrete should I order?
Add 5-10% for waste, spillage, uneven subgrade and over-excavation.
How long does concrete take to cure?
You can usually walk on it in 24-48 hours, drive on it in about 7 days and it reaches full strength at around 28 days.
What weather is best for pouring concrete?
Aim for 50-70°F. Cold slows curing; heat speeds set and can cause cracking. Use proper curing methods and follow supplier advice.
How do I use the calculator for irregular shapes or slopes?
Break the area into simple shapes (rectangles/circles) and add the volumes. For slopes, use average thickness = (min + max) ÷ 2.
Should I use bagged concrete or ready mix?
Consider your project size and convenience needs. Bagged concrete is better for smaller projects and allows precise batching. It also offers ease of transport and storage, but it requires manual mixing. Ready-mix concrete saves time on larger projects. It arrives pre-mixed, ensuring consistency and quality. However, it requires careful planning for delivery and may cost more.
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Last updated: October 15, 2025