Square Footage Calculator (Feet and Inches)
Calculate square footage in feet and inches without doing the math yourself. Enter your length and width exactly as you measured them — 12 ft 6 in by 10 ft 3 in — and get the total area in square feet instantly. It’s free, works on any device, and handles rooms, floors, walls, tiles, yards, and any rectangular space you need to size.
This calculator was built for anyone who’s ever stood in a room with a tape measure, jotted down “14′ 7″”, and then wondered how to turn that into square feet. Whether you’re buying flooring, ordering paint, planning a renovation, quoting a job, or listing a property, this tool removes the guesswork. No unit conversions. No formulas. Just accurate square footage in seconds.
Below the calculator, you’ll find the exact formula it uses, a conversion table for inches to decimal feet, room-size references, waste-allowance guides for flooring and paint, and answers to the most common measurement questions.
What Is Square Footage?
Square footage is the measurement of a two-dimensional area, expressed in square feet (sq ft or ft²). One square foot equals a square that is 12 inches long on every side — or 144 square inches. It’s the standard unit of area used in the United States and other countries that use imperial measurements, and it appears everywhere from real-estate listings and construction quotes to flooring receipts and HVAC specifications.
The formula for square footage is simple:
Area (sq ft) = Length (ft) × Width (ft)
The complication is that most people don’t measure in whole feet. A tape measure gives you feet and inches — “12 feet 7 inches” — and you can’t just multiply 12.7 × 10.4. Inches must first be converted to decimal feet. That’s the step our calculator handles automatically.
How the Calculator Works
Most measuring tapes give you feet and inches — not decimals. Our calculator matches how you actually measure, so you don’t have to convert 7 inches into 0.5833 feet in your head.
Here’s the process the tool runs behind the scenes:
- It takes the inches you entered for length and divides them by 12, converting them to decimal feet.
- It adds that decimal to the whole feet value to get the total length in decimal feet.
- It repeats the same conversion for the width.
- It multiplies length by width to produce area in square feet, rounded to two decimal places.
You get an accurate result down to the hundredth of a square foot — enough precision for flooring, tile, paint, and material orders.
How to Use the Square Footage Calculator
- Measure the length of your space in feet and inches. Run your tape from one wall to the opposite wall at floor level.
- Measure the width of your space in feet and inches, perpendicular to the length.
- Enter both measurements into the calculator fields above. Use the “feet” and “inches” inputs — you don’t need to convert anything.
- Click “Calculate” to see the total area in square feet.
- For irregular spaces, break the area into rectangles, calculate each one, and add the totals together.
- For flooring, tile, or paint, multiply your total by 1.10 (or your material’s recommended waste factor) to know how much to actually order.
How to Calculate Square Footage From Feet and Inches (Manually)
If you’d rather do the math by hand — or want to check the calculator’s output — here’s the process:
- Convert inches to feet. Divide the inches by 12. Example: 6 inches ÷ 12 = 0.5 feet.
- Add the decimal to the feet. Example: 12 ft 6 in = 12 + 0.5 = 12.5 ft.
- Repeat for the second measurement. Example: 10 ft 3 in = 10 + 0.25 = 10.25 ft.
- Multiply length by width. Example: 12.5 ft × 10.25 ft = 128.13 sq ft.
It’s straightforward — but doing it for every room, wall, or tile job adds up fast. That’s why the calculator exists.
Inches to Decimal Feet Conversion Table
Use this quick reference to convert inches into decimal feet by hand:
| Inches | Decimal Feet |
| 1 in | 0.083 ft |
| 2 in | 0.167 ft |
| 3 in | 0.250 ft |
| 4 in | 0.333 ft |
| 5 in | 0.417 ft |
| 6 in | 0.500 ft |
| 7 in | 0.583 ft |
| 8 in | 0.667 ft |
| 9 in | 0.750 ft |
| 10 in | 0.833 ft |
| 11 in | 0.917 ft |
| 12 in | 1.000 ft |
To convert any inch value not shown, divide by 12. For fractions of an inch (like ½” or ¾”), convert the fraction to decimal first (½ = 0.5, ¾ = 0.75), add it to the whole inches, then divide the total by 12.
Common Room Sizes and Their Square Footage
Here’s a quick reference for standard room dimensions and their total square footage — useful for sanity-checking your own measurements or estimating a space you can’t measure yet:
| Room Dimensions (ft) | Square Footage |
| 8 × 10 | 80 sq ft |
| 10 × 10 | 100 sq ft |
| 10 × 12 | 120 sq ft |
| 12 × 12 | 144 sq ft |
| 12 × 14 | 168 sq ft |
| 12 × 16 | 192 sq ft |
| 14 × 16 | 224 sq ft |
| 15 × 20 | 300 sq ft |
| 20 × 20 | 400 sq ft |
| 20 × 25 | 500 sq ft |
What You Can Use This Calculator For
Square footage matters any time you’re working with area. Common uses include:
- Flooring: Hardwood, laminate, vinyl, tile, and carpet are all sold by the square foot. Measure each room in feet and inches, then add 5–15% for cutting waste depending on the material and layout.
- Paint and wall coverings: Calculate wall area (height × width, minus doors and windows) to know how many gallons or rolls to buy. One gallon typically covers 350–400 sq ft.
- Tiling: Backsplashes, showers, and floors all need accurate square footage before you order — and tile is expensive to reorder.
- Landscaping: Sod, mulch, gravel, artificial turf, and pavers are priced per sq ft. A quick measurement prevents costly overages.
- Real estate: Listings, appraisals, and rent-per-sq-ft calculations depend on accurate area measurements. Buyers and appraisers cross-check these numbers.
- Renovation & construction: Drywall, insulation, roofing, siding, and concrete are all quoted per square foot on contractor estimates.
- HVAC sizing: Air conditioner and heater BTU requirements are based on room square footage — undersizing means a system that never keeps up.
- Cleaning services: Professional cleaners often quote by the square foot, especially for commercial spaces and post-construction cleanup.
- Property tax and insurance: Square footage affects tax assessments and replacement-cost insurance calculations.
Example 1: A Simple Rectangular Room
You’re carpeting a bedroom that measures 14 feet 8 inches long by 11 feet 3 inches wide.
- Length: 14 ft 8 in = 14 + (8 ÷ 12) = 14.667 ft
- Width: 11 ft 3 in = 11 + (3 ÷ 12) = 11.25 ft
- Area: 14.667 × 11.25 = 165.00 sq ft
Add 10% for waste (16.5 sq ft), and you’d order roughly 181.5 sq ft of carpet.
Example 2: An L-Shaped Living Room
L-shaped rooms are just two rectangles joined together. Measure each rectangle separately, calculate each area, then add them.
Say your living room has:
- Main section: 18 ft × 14 ft 6 in = 18 × 14.5 = 261 sq ft
- Extension (dining nook): 8 ft × 10 ft 6 in = 8 × 10.5 = 84 sq ft
- Total area: 261 + 84 = 345 sq ft
This method works for any complex shape — split it into rectangles, calculate each, and sum the results.
Example 3: A Whole House
To calculate the square footage of a full house, measure each room individually and add them together. Include hallways, closets, and stairwells (measured at floor level). Exclude unfinished basements, garages, and open-to-below spaces unless local convention says otherwise.
A quick example for a small home:
- Bedroom 1: 12 × 12 = 144 sq ft
- Bedroom 2: 10 × 11 = 110 sq ft
- Living room: 15 × 18 = 270 sq ft
- Kitchen: 10 × 12 = 120 sq ft
- Bathroom: 5 × 8 = 40 sq ft
- Hallway & closets: 60 sq ft
- Total: 744 sq ft
How to Measure Non-Rectangular Shapes
Triangles
Area = ½ × base × height. Measure the base of the triangle and the perpendicular height from the base to the opposite point.
Circles
Area = π × radius². Measure the diameter, divide by two to get the radius, square it, and multiply by 3.14159. A circular patio with a 10-ft diameter has a radius of 5 ft, so area = 3.14159 × 25 = 78.54 sq ft.
Trapezoids
Area = ½ × (base 1 + base 2) × height. Useful for lots and yards with two parallel sides of different lengths.
Complex shapes
Break the space into simpler shapes — rectangles, triangles, and half-circles — calculate each individually, then add them together. This “divide and conquer” method works for any floor plan, no matter how irregular.
Waste Allowance by Material
Never order the exact square footage of your space — cuts, mistakes, and future repairs all consume material. Use this chart to add a waste factor to your calculated area:
| Material / Layout | Recommended Waste |
| Standard tile / rectangular layout | 10% |
| Diagonal or herringbone tile | 15% |
| Hardwood / laminate planks | 7–10% |
| Vinyl plank / LVP | 10% |
| Carpet (broadloom) | 10–20% |
| Wallpaper (straight match) | 10% |
| Wallpaper (drop match) | 15–20% |
| Paint (per coat) | Add 10% to total wall area |
For irregular rooms with many cuts, or high-value materials like natural stone, err on the higher end. For future repairs, buy at least one extra box of tile or plank flooring — dye lots and production runs change over time and matching later is nearly impossible.
Square Feet Conversions to Other Units
Sometimes you need square footage expressed in another unit — square inches for small tile work, square meters for international products, square yards for carpet and concrete, or acres for land.
| Square Feet | Square Inches | Square Meters | Square Yards |
| 1 sq ft | 144 sq in | 0.0929 sq m | 0.111 sq yd |
| 10 sq ft | 1,440 sq in | 0.929 sq m | 1.111 sq yd |
| 100 sq ft | 14,400 sq in | 9.29 sq m | 11.11 sq yd |
| 500 sq ft | 72,000 sq in | 46.45 sq m | 55.56 sq yd |
| 1,000 sq ft | 144,000 sq in | 92.90 sq m | 111.11 sq yd |
| 43,560 sq ft | — | 4,046.86 sq m | 4,840 sq yd (= 1 acre) |
Key conversion factors:
- 1 sq ft = 144 sq in
- 1 sq ft = 0.0929 sq m
- 1 sq ft = 0.1111 sq yd (or divide sq ft by 9)
- 1 acre = 43,560 sq ft
- 1 sq m = 10.764 sq ft
Tips for Accurate Square Footage Measurements
- Measure at floor level, not eye level — walls aren’t always plumb, and baseboards can throw off higher measurements.
- Round to the nearest inch, not the nearest foot, for better accuracy. A one-foot rounding error on a 12×15 room adds up to 15+ sq ft.
- For L-shaped or T-shaped rooms, split them into rectangles and calculate each separately.
- Measure twice, write it down once. It’s far faster than remeasuring after you’ve started ordering.
- Use a laser measure for rooms over 20 feet — tape measures sag and misread over long distances.
- Deduct fixed obstructions (kitchen islands, built-ins) only if they truly reduce the usable area you’re working with.
- Always add a waste allowance when ordering flooring, tile, or wallpaper — typically 5% for straight patterns and 10–15% for diagonals or complex layouts.
- Sketch your floor plan on paper as you measure. It helps you spot irregularities and check your math later.
Common Mistakes to Avoid
- Confusing feet with inches. A “5” typed into the wrong field can multiply your error by 12. Double-check units before calculating.
- Forgetting to convert inches to decimal feet. 12 ft 6 in is not 12.6 ft — it’s 12.5 ft. Six inches is half a foot, not six tenths.
- Measuring only visible floor. For flooring, measure wall-to-wall — you’ll need material under appliances, furniture, and future rearrangements.
- Ignoring waste allowance. Ordering the exact calculated square footage guarantees a second trip to the store — or a mismatched dye lot.
- Adding square feet across different units. Never mix sq ft with sq yards or sq meters without converting first.
- Rounding too early. Keep at least two decimal places through your calculation and round only at the end.
Frequently Asked Questions
How do I calculate square footage in feet and inches?
Convert the inches to a decimal by dividing by 12, add it to the feet, then multiply length by width. For example, 10 ft 6 in × 8 ft = 10.5 × 8 = 84 sq ft. Our calculator does this automatically — just enter feet and inches into the input fields and press Calculate.
What is the formula for square footage?
The formula is Length × Width. Both measurements must be in the same unit (feet), and the result is expressed in square feet (sq ft or ft²).
How many square feet is a 12×12 room?
A room that measures 12 feet by 12 feet is 144 square feet.
How many square feet is a 10×10 room?
A 10-foot by 10-foot room is 100 square feet.
How many square feet is a 20×20 room?
A 20-foot by 20-foot room is 400 square feet.
How do I convert inches to square feet?
You don’t convert inches directly to square feet — you convert your inch measurements to decimal feet first (by dividing by 12), then multiply length by width. If you already have measurements in square inches, divide by 144 to get square feet.
How do I calculate square footage of an irregular room?
Divide the room into rectangles or squares. Calculate the square footage of each section separately using length × width, then add all the sections together for the total area. For circular or triangular sections, use their specific area formulas (π × r² for circles, ½ × base × height for triangles).
Do I need to convert inches to feet before using the calculator?
No. This calculator accepts feet and inches directly, so you can enter your measurements exactly as they appear on your tape measure.
How much extra should I add for waste?
For flooring and tile, add 10% for straight installations and 15% for diagonal patterns, herringbone, or rooms with lots of cuts. For carpet, plan for 10–20% depending on how much seaming is required. For paint, plan for one gallon per 350–400 sq ft of wall area, with a second coat.
How many square feet in a square yard?
One square yard equals 9 square feet. To convert square feet to square yards, divide by 9. Carpet and concrete are often priced per square yard.
How many square feet in an acre?
One acre equals 43,560 square feet, or about 208.7 feet on each side of a square.
How do I calculate square footage of walls for painting?
Measure the length and height of each wall, multiply them, and add the wall areas together. Then subtract the area of doors (typically 21 sq ft each) and windows (typically 15 sq ft each). One gallon of paint covers roughly 350–400 sq ft with one coat.
How is house square footage measured?
For real estate purposes, square footage is generally measured from the exterior walls, including all finished, heated, above-grade living space. Garages, unfinished basements, and open-to-below areas are typically excluded. Standards vary by region — ANSI Z765 is the most widely followed in the US.
Does this calculator work on mobile?
Yes. The calculator is fully responsive and works on smartphones, tablets, laptops, and desktops. You can use it on-site with your phone while measuring.
Is this calculator free to use?
Yes — the square footage calculator is 100% free, requires no sign-up or download, and can be used as often as you like.
Get Accurate Square Footage in Seconds
Skip the math, the conversion charts, and the second-guessing. Enter your feet-and-inches measurements above, hit calculate, and get the exact square footage you need for your next project — whether it’s a single tile backsplash or a whole-home flooring order.
Bookmark this page for your next measurement. And if you’re working with other units — square meters, square yards, or acres — check our related area calculators for quick conversions.