Square Footage Calculator
Add every room in your project, switch between feet and meters, and get a running total with an optional waste factor for flooring, tile, or paint. Results update as you type, no submit button needed.
| Room name | Length | Width | L-shape | Area | Remove |
|---|
- Total area
- 0 ft²
- With waste factor
- 0 ft²
- Total in the other unit
- 0 m²
- Rooms counted
- 0
How to measure a room for square footage
To find the square footage of a room, measure the length of one wall and the width of the adjacent wall, both in feet. Use a tape measure or a laser measure and run it along the floor from baseboard to baseboard for the most accurate reading. Round to the nearest inch, then convert to a decimal (6 inches becomes 0.5 feet). Multiply length by width to get the area in square feet. For a rectangular room this single calculation is all you need.
Most rooms are not perfect rectangles. Bay windows, closets, alcoves, and open-plan layouts add extra sections. The simplest way to handle this is to break the room into rectangles: measure each rectangular section separately, calculate its area, then add the sections together. If a fixed feature like a fireplace or a stairwell eats into the floor space, measure that section too and subtract it from the total.
Always measure at floor level, not at the widest point of the walls, since baseboards, closet doors, and door swings can make upper measurements misleading. If you are ordering flooring or tile, add a waste factor on top of the raw area to cover cuts, offcuts, and mistakes. This calculator does the arithmetic for multiple rooms and L-shapes automatically once you enter your measurements above.
Worked example
A bedroom measures 12 ft by 14 ft.
Area = 12 × 14 = 168 square feet.
In square meters: 168 × 0.092903 ≈ 15.61 m².
With a 10% waste factor for flooring: 168 × 1.10 = 184.8 square feet of material to order.
Square footage of common room sizes
Length times width, with the metric figure and the amount to order with a 10 percent waste factor for flooring or tile.
| Room size | Square feet | Square meters | With 10% waste |
|---|---|---|---|
| 10 x 10 ft | 100 sq ft | 9.29 m² | 110 sq ft |
| 10 x 12 ft | 120 sq ft | 11.15 m² | 132 sq ft |
| 10 x 14 ft | 140 sq ft | 13.01 m² | 154 sq ft |
| 11 x 12 ft | 132 sq ft | 12.26 m² | 145.2 sq ft |
| 12 x 12 ft | 144 sq ft | 13.38 m² | 158.4 sq ft |
| 12 x 14 ft | 168 sq ft | 15.61 m² | 184.8 sq ft |
| 12 x 16 ft | 192 sq ft | 17.84 m² | 211.2 sq ft |
| 14 x 16 ft | 224 sq ft | 20.81 m² | 246.4 sq ft |
| 14 x 18 ft | 252 sq ft | 23.41 m² | 277.2 sq ft |
| 16 x 20 ft | 320 sq ft | 29.73 m² | 352 sq ft |
| 18 x 22 ft | 396 sq ft | 36.79 m² | 435.6 sq ft |
| 20 x 20 ft | 400 sq ft | 37.16 m² | 440 sq ft |
Square footage of walls and ceilings
Ceiling: a flat ceiling has the same area as the floor, so a 12 by 14 room has a 168 square foot ceiling.
Walls: add the lengths of all the walls to get the perimeter, then multiply by the ceiling height. A 12 by 14 room has a perimeter of 52 feet; at 8 feet high that is 416 square feet of wall. Take off about 20 square feet per door and 15 per window if you are buying paint or wallpaper. The paint calculator does this for you.
What to do with the square footage
Once you have the area, the next question is usually how much material it takes. These tools and worked answers pick up where this page leaves off:
- Paint calculator. Walls, ceilings, doors, windows, and coats, in gallons or liters.
- Flooring calculator. Boxes of plank, tile, or carpet for one or more rooms, with a waste factor.
- Concrete calculator. Cubic yards and 40, 60, or 80 lb bags for slabs, footings, and columns.
- Cups to grams converter. New: kitchen conversions for flour, sugar, butter, and 31 more ingredients.
- How much paint for a bedroom? Gallons by bedroom size, 10x10 to 14x16.
- How much paint for a living room? Gallons by room size and ceiling height.
- How much paint for a bathroom? Usually one gallon, and the finish to use.
- How much paint for a 12x12 room? The full arithmetic for the most common room size.
- How much does a gallon of paint cover? The 350 to 400 square foot range explained.
- Paint coverage by surface type. Texture, bare drywall, wood, stucco, and brick.
- How much paint for two coats? Gallon figures by room size.
More project guides and kitchen conversions
Find a worked example for your next project, or convert baking measurements by ingredient.
Concrete and fence planning
- Concrete bags for a 10x10 slab. Compare bag sizes and see how slab thickness changes the estimate.
- Concrete bags for a fence post. Estimate a round post hole and understand the calculator's shortcut.
- Coverage of an 80 lb concrete bag. Find the square foot coverage at different pour thicknesses.
- Fence panels for a 100 foot fence. Work out panels and posts for a straight run.
- Fence post spacing. Choose spacing before counting posts and panels.
Kitchen measurement guides
Start with the kitchen conversion guides, or look up one cup of butter in grams, ounces, and sticks. Ingredient-specific guides explain measuring methods as well as conversions.
Frequently asked questions
How do I measure an L-shaped room?
Split the room into two rectangles at the corner of the L. Measure the length and width of the main rectangle, then the length and width of the smaller section that sticks out, and add the two areas together. If instead you are working around a built-in feature such as a fireplace hearth, measure that section separately and subtract it from the main rectangle. The calculator above has an "Add L-shape" option on each room row that does this addition or subtraction for you.
How do I convert square feet to square meters?
Multiply square feet by 0.092903 to get square meters, or divide by 10.7639. For example, 168 square feet is about 15.61 square meters. Switch the unit toggle above the room table to see every measurement and result converted automatically.
How much waste should I add for flooring?
A common rule of thumb is 10 percent extra for straightforward rectangular rooms, which covers cuts and the occasional mistake. Complex layouts, diagonal installation patterns, or materials with a repeat pattern like some tile or hardwood often need 15 to 20 percent. Check your flooring manufacturer's guidance for the specific product you are buying.
Does square footage include closets?
For flooring, paint, or material estimates, include closets and any enclosed space you plan to cover, since you still need material for that floor or those walls. For official real estate listings, standards vary by region; many appraisers use ANSI Z765 guidelines, which include closets but exclude unfinished areas such as garages and unfinished basements.