1. Select your shape
Choose from rectangle, circle, triangle, trapezoid, L-shape, annulus, or wall-and-window layouts to match your project.
What is wall with window square footage?
Wall with window square footage is the net surface area of a wall after subtracting the window opening, measured in square feet. The formula is: Paintable Area = (Wall Height x Wall Width) - (Window Height x Window Width). This gives you the exact amount of wall surface that needs paint, wallpaper, or siding.
Getting started
How to Calculate Wall with Window Square Footage
To calculate wall with window area: multiply wall height by wall width for total wall area, then subtract window height by window width. A 12x8 wall with a 3x4 window has a paintable area of 84 square feet (96 - 12 = 84).
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.
Wall and Window Shape
Calculate square foot of a wall minus window
Using measurements in feet:
- Wall Area (ft²) = Wall Height × Wall Width
- Window Area (ft²) = Window Height × Window Width
- Area (ft²) = Wall Area − Window Area
To subtract multiple windows of the same size from one wall, multiply window width by the number of windows and enter the total as window width. A wall 12 ft × 8 ft (3.66 m × 2.44 m) with a 3 ft × 4 ft window has a paintable area of 84 sq ft. Use this shape for walls with doors or other openings during painting or flooring installation projects.
Calculating Square Footage for Walls
Measure the wall width and the wall height in feet. Multiply the width by the height to get the total wall area in square feet. Subtract the area of any doors or windows to find the exact paint coverage required. A wall that is 12 feet wide and 8 feet tall has a total area of 96 sq ft. A 3 ft × 4 ft window removes 12 sq ft, leaving 84 sq ft of paintable surface.
To subtract multiple windows of the same size from one wall, multiply the window width by the number of windows. Enter the total as the window width in the Square Foot Calculator. Height remains the height of one window.
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 wall area minus a window?
Calculate total wall area (Height x Width), then subtract window area (Height x Width). A 10x8 wall with a 4x3 window = 80 - 12 = 68 sq ft of paintable area.
How do I account for multiple windows on one wall?
Calculate the area of each window and subtract all window areas from the total wall area. For identical windows, multiply one window area by the number of windows.
Should I subtract the window frame from calculations?
For most painting projects, subtract the entire window opening including the frame. If you plan to paint the frame, keep it in your calculations.
How much paint do I need for a wall with windows?
Calculate the net wall area (wall minus windows), then divide by 350-400 sq ft per gallon. This gives you the paint needed per coat.
Can I use this for walls with doors too?
Yes, treat a door as a window opening. Enter the door width and height as the window dimensions to subtract it from the wall area.
What if my window has an irregular shape?
For arched or round-top windows, calculate the rectangular portion plus the curved section. Use the circle calculator for the arch area and add it to the rectangular window area.