Room Size Calculator
Convert inches, feet, or meters to square footage with instant paint, tile, and rug recommendations
About This Tool
Room Size Calculator
Whether you are measuring a backsplash in inches, a living room in feet, or an apartment in meters, this calculator gives you the square footage in every unit at once. Pick rectangle or L-shape, enter your dimensions, and watch the room render as a live diagram. Add ceiling height to unlock wall area for paint and wallpaper, plus room volume for HVAC sizing. Add a price per square foot for flooring cost. Each result links directly to our paint, tile, rug, wallpaper, and furniture budget calculators so you can plan a whole room without retyping the dimensions. Built on the same conversion math used across 2,000+ real interior design projects.
What You Get
Personalized estimates based on your specific measurements
Results update instantly as you adjust inputs
Professional tips and product recommendations included
Free to use with no sign-up required
Pro Tip
Results are estimates based on standard measurements. For a personalized assessment tailored to your specific project, book a free consultation with our design team.
Step by Step
How to Use This Calculator
Pick your unit
Choose feet, inches, meters, or centimeters. The calculator converts everything to square footage and other area units automatically.
Enter length and width
Type the length and width of your room. The visual diagram updates as you type so you can see the shape and dimensions.
Add L-shape or walls (optional)
Toggle L-shape for two-rectangle rooms. Add ceiling height, doors, and windows to calculate wall area for paint or wallpaper.
Use the linked tools
See square footage, perimeter, wall area, and recommendations for paint gallons, tile boxes, rug size, and wallpaper rolls.
Common Questions
Frequently Asked Questions
How do I convert inches to square feet?
Multiply the length in inches by the width in inches, then divide by 144 (since one square foot equals 144 square inches). For a 144" x 168" room, that is 24,192 square inches divided by 144, or 168 square feet. This calculator does it instantly for you when you select inches as your unit.
How many square feet is a 12x12 room?
A 12 foot by 12 foot room is exactly 144 square feet. That is also 13.4 square meters, 16 square yards, or 20,736 square inches. For comparison, a 10x10 room is 100 sqft and a 14x16 room is 224 sqft, which the calculator will show you instantly.
How do I calculate square footage for an L-shaped room?
Split the L-shape into two rectangles, calculate the square footage of each, and add them together. This calculator does the math for you when you toggle "L-Shape" and enter both sets of dimensions. The diagram updates to show the combined shape, and the total sqft includes both areas.
How many square feet is a square meter?
One square meter equals 10.7639 square feet. So a 4 meter by 5 meter room is 20 square meters, or about 215 square feet. The calculator outputs sqft, sqm, sqyd, and sqin side by side so you can compare units instantly without doing the math.
How do I measure my room for flooring?
Measure the length and width of your room at the longest points in inches or feet. For irregular shapes, divide the room into rectangles and measure each one. Enter the dimensions here to get total square footage, then click through to the tile calculator for box counts including waste.
How many gallons of paint do I need for a room?
One gallon of paint covers about 350 square feet of smooth wall, one coat. For a 12x12 room with 8 foot ceilings, the wall area is around 384 sqft after subtracting a door and two windows, so one gallon covers one coat. This calculator estimates paint gallons automatically once you add ceiling height.
What is the difference between square feet and square yards?
One square yard equals 9 square feet, so divide sqft by 9 to get sqyd. Carpet and some flooring is sold by the square yard, while tile, hardwood, and paint coverage are usually sold per square foot. The calculator shows both units at once.
How do I calculate wall area from room dimensions?
Wall area equals the room perimeter multiplied by the ceiling height, then subtract any door and window openings. For a 12x14 room with 8 foot ceilings, that is 52 ft of perimeter x 8 ft = 416 sqft, minus roughly 36 sqft for one door and two windows, so about 380 sqft of paintable wall. The calculator does this for you once you enter ceiling height.
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