Concrete Calculator

Calculate Concrete Volume

Concrete Calculator Comparison

How our calculator compares to alternatives across key features.

How to Calculate Concrete

Getting an accurate concrete estimate is critical for any construction project. Ordering too little means costly delays and cold joints, while ordering too much wastes money and creates disposal challenges. This calculator handles the math for five common shapes.

Slab Calculations

Slabs are the most common concrete pour. Enter the length and width of the area, then specify the depth (typically 4 inches for walkways, 5-6 inches for driveways). The calculator multiplies these dimensions and converts to cubic yards, the standard ordering unit for ready-mix concrete.

Footing Calculations

Footings support walls and structures, distributing load to the soil. They are typically deeper and narrower than slabs. Enter the total linear length of the footing, its width, and depth. Standard residential footings are 12 inches wide and 12 inches deep, though local codes may require larger dimensions based on soil conditions.

Column Calculations

Round columns use the cylinder volume formula (pi x radius squared x height). Specify the diameter, height, and how many columns you need. Common column diameters are 8, 10, and 12 inches for residential post footings.

Stair Calculations

Concrete stairs are calculated as stacked rectangular volumes. Enter the width, rise per step, run per step, number of steps, and platform thickness. Standard residential steps have a 7-inch rise and 11-inch run per building code requirements.

Curb Calculations

Curbs are modeled as an L-shaped cross-section running along a specified length. Enter the curb length, width, height, and flag (base) width. Standard curbs are typically 6 inches wide, 18 inches tall with a 12-inch flag.

The mix ratio determines the strength, workability, and finish quality of your concrete. Choosing the right mix depends on the application and load requirements.

3)

One part cement, two parts sand, three parts aggregate. This mix produces approximately 3,000-3,500 PSI concrete, suitable for sidewalks, patios, and non-structural slabs. It offers good workability and a reasonable set time.

2.5)

This cement-rich mix achieves 4,000-5,000 PSI and is appropriate for structural footings, load-bearing columns, and driveways that must support heavy vehicles. It sets faster and requires careful water management to avoid cracking.

Decorative Mix

Uses finer aggregates and sometimes white cement for a smoother finish. PSI varies by formulation. This mix is for stamped concrete, exposed aggregate finishes, and colored concrete applications where surface appearance matters as much as structural performance.

Steel reinforcement bars (rebar) dramatically increase the tensile strength of concrete. While concrete handles compression well, it is weak in tension. Rebar handles the tension forces, preventing cracks from propagating and structural failure.

For residential slabs, #4 rebar (1/2-inch diameter) is standard. Place it in a grid pattern at 12-inch or 18-inch on-center spacing, supported on chairs to maintain proper position within the slab. The rebar should sit at approximately 1/3 depth from the top of the slab.

Footings typically require #5 rebar (5/8-inch) running longitudinally with transverse ties. Columns need vertical bars with horizontal ties (stirrups). Always check local building codes, as requirements vary by jurisdiction and soil conditions.

Ready-mix concrete pricing varies by region, mix design, and order size. The typical range for standard concrete delivery in 2026 is $125-$165 per cubic yard. Consider these additional costs when budgeting:

Short load fees apply when ordering less than a full truck (typically under 10 cubic yards). These fees range from $25-$75 per yard under the minimum. Saturday delivery and afternoon pours often carry a premium of $5-$15 per yard.

Pump truck rental adds $150-$300 per hour when the truck cannot pour directly into the forms. Finishing labor typically runs $3-$8 per square foot for standard broom finish, and $8-$15 per square foot for stamped or decorative finishes.

The waste factor in our calculator accounts for spillage, over-excavation, and form irregularities. Use 5% for simple rectangular pours with experienced crews, and 10-15% for complex shapes, slopes, or less experienced crews.