1. Select your shape
Choose from rectangle, circle, triangle, trapezoid, L-shape, annulus, or wall-and-window layouts to match your project.
What is concrete square footage?
Concrete square footage is the surface area of a concrete slab or project measured in square feet. To find concrete square footage, measure the length and width of the area in feet and multiply them together. Concrete square footage is used to estimate the volume of concrete needed (area x depth) and total material cost.
Getting started
How to Calculate Square Footage for Concrete
To calculate square footage for concrete, measure the project length and width in feet and multiply. To find volume in cubic yards, multiply area (sq ft) by thickness (ft), then divide by 27. A 20x10 ft patio that is 4 inches thick needs: 200 sq ft x 0.333 ft / 27 = 2.47 cubic yards of concrete.
2. Enter your measurements
Input dimensions in feet, inches, yards, meters, or centimeters. The Square Foot Calculator converts units automatically.
3. Get area and cost
View results in square feet, square yards, square meters, and acres. Add a material price per unit to estimate total project cost.
Quick reference
Reference
1 acre = 43,560 square feet
1 square yard = 9 square feet
1 square meter = 10.764 square feet
1 square inch = 0.00064516 square feet
Material pricing
Calculate Cost of Materials
Enter the price per square foot of material to estimate total cost. The calculator accepts pricing in square feet, square inches, square yards, or square meters and converts to the correct total based on your area.
There are 2 steps to calculate material cost:
- Enter the price per unit area. For tiling projects, enter the price per box and the number of square feet each box covers. For carpet, enter the cost per square yard. For flooring installation with hardwood or laminate, enter the cost per square foot.
- Select the unit of area that matches your pricing. The Square Foot Calculator multiplies your total area by the unit price to produce an estimated material cost, including labor costs when added to the per-unit price.
To calculate the volume of bulk materials like mulch or gravel for landscaping, convert area to cubic yards or cubic meters by multiplying the area by the depth of material.
Core formula
Basic Formula for Area
Area is the amount of space occupied by a 2-dimensional shape. The shape could be a floor, a wall, a playground, or a field. The simplest formula for area applies to any rectangular shape:
Area = Length × Width
Measure the length and width of the space in feet. Multiply the two values to get the area in square feet. A rectangular room that is 12 feet (3.66 meters) long and 10 feet (3.05 meters) wide has an area of 120 sq ft (11.15 sq m).
Square yardage is area measured in yards, and square meters is area measured in meters. Measure in feet, find the area in square feet, then convert to the unit you need.
For an L-shape room, split the floor into 2 rectangular sections, calculate each area, and add the results. Convert all measurements to the same unit before multiplying, if your dimensions are in different units like inches and feet.
Basic Length Conversion
Convert other units of measure to feet with these 4 formulas:
| From | To Feet | Formula |
|---|---|---|
| Inches | Feet | Divide by 12 |
| Yards | Feet | Multiply by 3 |
| Meters | Feet | Multiply by 3.28084 |
| Centimeters | Feet | Divide by 30.48 |
For example, 48 inches ÷ 12 = 4 feet. A measurement of 5 meters × 3.28084 = 16.40 feet. The Square Foot Calculator handles these conversions automatically when you select the input unit.
Unit conversion
Area Conversion
Measure your space in inches or centimeters, calculate area in square inches or square centimeters, then convert to any unit you need, including square feet, square yards, square meters, or acres.
| Unit | Square Feet Equivalent |
|---|---|
| 1 sq ft | 144 sq in |
| 1 sq yd | 9 sq ft |
| 1 sq m | 10.764 sq ft |
| 1 acre | 43,560 sq ft |
A 300 sq ft room equals 33.33 sq yd, 27.87 sq m, or 43,200 sq in. The Square Footage Calculator displays all conversions at once so you can compare units for flooring, carpet, or tiling projects without manual math.
Shape formulas
Area Formulas for Different Shapes
The Square Foot Calculator supports 11 shape formulas for construction, interior design, landscaping, and flooring projects. Each formula below includes a diagram with labeled dimensions.
Rectangle Shape
Calculate square foot of a rectangle
Using measurements in feet: Area (ft²) = Length × Width. This is the most common formula for calculating square footage of a rectangular room, floor, wall, or field. A room 15 feet (4.57 meters) long and 12 feet (3.66 meters) wide has a Rectangle Area of 180 sq ft (16.72 sq m).
Circle Shape
Calculate square foot of a circle
Using measurements in feet: Area (ft²) = π × (Diameter ÷ 2)², where π = 3.14159. This formula uses the diameter (the full width of the circle). Divide the diameter by 2 to get the radius: diameter = 2 × radius. A circular patio with a 10-foot (3.05-meter) diameter has an area of 78.54 sq ft. The Square Foot Calculator uses a high-precision π constant for accurate results on larger landscaping and construction projects.
Waste factor
Adding 10% Surplus for Materials
Add a 10% surplus to your calculated area to account for material waste during cutting, breakage, and pattern matching. This waste factor applies to flooring, carpet, tiling projects, and landscaping materials.
Original Area
100 sq ft
+10%
Order Amount
110 sq ft
Total Material = Area × 1.10
A room with 200 sq ft of floor area needs 220 sq ft of material: 200 × 1.10 = 220 sq ft. Increase the surplus to 15% (multiply by 1.15) for diagonal flooring installation patterns or complex tiling projects with many cuts. The Square Foot Calculator includes a waste factor field for this calculation.
FAQ
Frequently Asked Questions
How do I calculate square footage for a concrete slab?
Multiply length by width in feet to get square footage. A 20x10 ft slab is 200 square feet. To find cubic yards of concrete needed, multiply area by thickness in feet, then divide by 27.
How much concrete do I need for a 10x10 slab?
A 10x10 ft slab (100 sq ft) at 4 inches thick needs about 1.23 cubic yards of concrete. Calculation: 100 x 0.333 / 27 = 1.23 cubic yards. Order 10% extra for spillage.
How do I calculate concrete for a driveway?
Measure driveway length and width, multiply for area, then calculate volume based on 4-6 inch thickness. A 40x12 ft driveway (480 sq ft) at 5 inches thick needs about 7.4 cubic yards.
How much does concrete cost per square foot?
Concrete costs $4-8 per square foot for a standard 4-inch slab including materials and labor. Decorative concrete (stamped, stained) costs $8-18 per square foot.
How thick should a concrete slab be?
Standard residential slabs are 4 inches thick. Driveways should be 5-6 inches. Garage floors and heavy-load areas need 6 inches or more. Thicker slabs use more concrete but last longer.
How many bags of concrete for 100 square feet?
For a 4-inch thick slab covering 100 sq ft, you need approximately 34 bags (80 lb each). Each 80 lb bag makes about 0.6 cubic feet. Total volume needed: 100 x 0.333 = 33.3 cubic feet.