Interior projects are where accurate measuring pays off the most. Flooring and tile are sold in boxes, paint by the gallon or liter, drywall by the sheet and wallpaper by the roll, and each product has its own coverage and waste rules. These calculators handle the area math and the packaging so you know exactly what to buy.
All Flooring & Walls Calculators
Choosing the Right Calculator
- Installing laminate, vinyl plank, hardwood or carpet? The Flooring Calculator gives square footage and boxes with a waste allowance.
- Tiling a floor, shower or backsplash? The Tile Calculator counts tiles, boxes and grout based on tile size and joint width.
- Repainting a room? The Paint Calculator subtracts doors and windows and tells you how many gallons or liters you need for each coat.
- Finishing a basement or new wall? The Drywall Calculator works out sheets, screws and joint compound.
- Hanging wallpaper? The Wallpaper Calculator accounts for roll size and pattern repeat.
Measuring Floors and Walls
For floors, measure the length and width of each rectangular section and add them together. For L-shaped rooms, split the room into two rectangles. For walls, measure the perimeter of the room and multiply by the wall height, then subtract large openings such as doors and windows.
Write your measurements down room by room. Many people run the calculator once per room, which also makes it easier to buy materials in batches.
How Much Waste to Allow
- Straight-lay flooring and tile: about 10 percent extra.
- Diagonal or herringbone patterns: 15 to 20 percent extra because of extra cuts.
- Paint: buy enough for two coats and keep a small amount for touch-ups.
- Wallpaper with a large pattern repeat: allow an extra roll or two for matching.
Buying all your flooring, tile or wallpaper at once also helps you get the same dye lot or batch, which avoids visible color differences.