Concrete Calculator

How to Calculate Concrete Volume manually

You can calculate concrete volume by multiplying the measurements for each structure. Convert inches to feet before using the formula.

Concrete Slab

A concrete slab uses length, width, and thickness to find its volume. Keep all measurements in the same unit before calculating.

Formula

$Volume = Length \times Width \times Thickness$

Step by step Guide

1. Measure the slab length in feet.
2. Measure the slab width in feet.
3. Convert thickness from inches to feet.
4. Multiply length × width × thickness.
5. Divide cubic feet by 27 to get cubic yards.

Practical Example

A slab measures 12 ft × 10 ft × 4 in. Convert 4 in to 0.333 ft. Then, $12 \times 10 \times 0.333 = 39.96$ cubic feet. Divide by 27 to get about $1.48$ cubic yards.

Concrete Footer

A concrete footing supports walls, columns, or other structures. Its volume depends on length, width, and footing depth.

Formula

$Volume = Length \times Width \times Depth$

Step by step Guide

1. Measure the footing length in feet.
2. Measure the footing width in feet.
3. Convert depth to feet if needed.
4. Multiply length × width × depth.
5. Divide cubic feet by 27 for cubic yards.

Practical Example

A footing measures 20 ft long, 2 ft wide, and 8 in deep. Convert 8 in to 0.667 ft. Then, $20 \times 2 \times 0.667 = 26.68$ cubic feet. That equals about $0.99$ cubic yards.

Concrete Column

A round concrete column needs its diameter and height. You can use the cylinder formula to estimate its concrete volume.

Formula

$Volume = \pi \times Radius^2 \times Height$

Step by step Guide

1. Measure the column diameter.
2. Divide the diameter by 2 for the radius.
3. Convert measurements to feet.
4. Multiply $\pi \times radius^2 \times height$.
5. Divide cubic feet by 27 for cubic yards.

Practical Example

A column has a 2 ft diameter and is 10 ft high. Its radius is 1 ft. The volume is $3.1416 \times 1^2 \times 10 = 31.42$ cubic feet. That equals about $1.16$ cubic yards.

Concrete Stair

Concrete stairs need more care because each step has a different height. For a basic estimate, calculate the stepped section as stacked rectangular blocks.

Formula

$Volume = Width \times Tread \times Riser \times [n(n+1) \div 2]$

Here, $n$ means the number of risers.

Step by step Guide

1. Measure the stair width.
2. Measure the tread depth.
3. Measure the riser height.
4. Count the number of risers.
5. Apply the formula and convert to cubic yards.

Practical Example

A stair is 4 ft wide with 6 in treads and 6 in risers. It has 8 risers. The volume is $4 \times 0.5 \times 0.5 \times 36 = 36$ cubic feet. That equals $1.33$ cubic yards.

Concrete Bag Coverage Table

Concrete bags produce different amounts of concrete based on their weight and product yield. Use the product label for the most accurate coverage.

Note: Actual bag yield can vary by product. Check the manufacturer's coverage information before buying concrete bags.