1. Select your shape
Choose from rectangle, circle, triangle, trapezoid, L-shape, annulus, or wall-and-window layouts to match your project.
What is roofing square footage?
Roofing square footage is the total surface area of a roof measured in square feet. To find roofing square footage, multiply the roof length by width, then account for pitch/slope by multiplying by a pitch factor. Roofing is sold in "squares" where 1 roofing square = 100 sq ft. A 2,000 sq ft roof needs 20 squares of material.
Getting started
How to Calculate Roofing Square Footage
To calculate roofing square footage, measure the footprint (ground-level length x width), then multiply by the pitch factor for your roof slope. A 4/12 pitch has a factor of 1.054, a 6/12 pitch uses 1.118, and an 8/12 pitch uses 1.202. Divide total square footage by 100 to get roofing squares.
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).
Triangle Shape
Calculate square foot of a triangle using base and height
Using measurements in feet: Area (ft²) = ½ × Base × Height. This formula is simpler than Heron's formula and works when you know the base and the perpendicular height of the triangle. A triangle with a 10-foot (3.05-meter) base and 6-foot (1.83-meter) height has an area of 30 sq ft (2.79 sq m).
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 roof square footage?
Measure the roof footprint (length x width from the ground), then multiply by the pitch factor. A 40x30 ft footprint (1,200 sq ft) with a 6/12 pitch: 1,200 x 1.118 = 1,342 sq ft of actual roof area.
What is a roofing square?
A roofing square equals 100 square feet of roof area. A 2,000 sq ft roof requires 20 roofing squares. Shingles are sold in bundles, with 3 bundles typically equaling 1 roofing square.
How many shingles do I need per square foot?
Standard 3-tab shingles require about 3 bundles per roofing square (100 sq ft). For a 1,500 sq ft roof, you need 15 squares or 45 bundles of shingles, plus 10-15% for waste.
How do I account for roof pitch in my calculation?
Multiply the flat footprint area by the pitch factor: 3/12 pitch = 1.031, 4/12 = 1.054, 5/12 = 1.083, 6/12 = 1.118, 8/12 = 1.202, 10/12 = 1.302, 12/12 = 1.414.
How much does roofing cost per square foot?
Asphalt shingles cost $3.50-5.50/sq ft installed, metal roofing costs $7-14/sq ft, and tile roofing costs $10-20/sq ft. A 2,000 sq ft roof with asphalt shingles typically costs $7,000-11,000.
How many squares is a typical house roof?
A typical single-story home has 15-25 roofing squares (1,500-2,500 sq ft of roof area). Two-story homes have smaller roof footprints, typically 10-20 squares.