Room Area Calculator
Calculate floor area, ceiling area, room perimeter, total wall area, and approximate paintable wall area from a single set of room measurements.
Enter the Dimensions
Room size
Doors & windows
Paintable wall area assumes approximately 21 sq ft per door and 15 sq ft per window.
Your room measurements will appear here
Enter the dimensions above and select Calculate Room.
What Does This Room Calculator Measure?
A room can have several useful measurements depending on the project. Flooring and rugs usually depend on floor area, ceiling projects use ceiling area, trim and baseboards often depend on perimeter, while painting and wall coverings depend on wall surface area.
This tool calculates all of these from the same room dimensions so you can use one measurement set for multiple home-improvement projects.
Floor Area
Length × Width
Perimeter
2 × (Length + Width)
Total Wall Area
Perimeter × Wall Height
Paintable Wall Area
Wall Area − Door & Window Area
Use Floor Area for Flooring and Rugs
Floor area is the basic measurement used for many flooring products. It can also help when comparing rug sizes or estimating materials such as laminate, vinyl plank, hardwood, or tile.
Length × Width
Perimeter × Height
Use Wall Area for Paint and Wall Coverings
Total wall area is calculated from the room perimeter and wall height. This calculator can also subtract approximate door and window areas to provide a rough paintable surface measurement.
For projects that require precise ordering, measuring the actual width and height of openings can provide a more accurate result.
What If the Room Is Not Rectangular?
Divide an irregular room into smaller rectangles. Calculate the area of each section separately, then add the areas together. This approach is often easier and more reliable than trying to estimate an irregular floor plan as one shape.
Room Area Calculator Questions
Is floor area the same as ceiling area?
In a rectangular room with a flat ceiling, yes. Both are calculated as room length multiplied by room width. Sloped, vaulted, or irregular ceilings require a different measurement.
How do I calculate the room perimeter?
Add the room length and width, then multiply the result by two. Perimeter is useful for baseboards, trim, and other materials installed around the edge of a room.
Does wall area include doors and windows?
Total wall area includes the entire wall surface. The calculator also provides an approximate paintable wall area after subtracting average door and window sizes.
Can I use this for rooms with sloped walls or ceilings?
The basic calculator assumes vertical walls and a flat rectangular ceiling. Sloped ceilings, alcoves, columns, staircases, and other unusual features should be measured separately.
Are the results exact?
No. Results are mathematical estimates based on the dimensions and assumptions entered. Actual project measurements may differ because of room shape, construction details, wall thickness, openings, and measurement accuracy.