Square Footage Calculator
Calculate area for any shape or room. Multi-room totals, unit conversion, waste factor, and cost estimate. Free, no signup.
Measure rooms, floors, patios, and odd-shaped spaces. Multi-room mode totals a whole house, something most free calculators skip.
Square footage is the total flat area inside a space, measured in square feet (length × width for rectangles). It tells you how much flooring, paint, carpet, sod, or drywall a project needs. Enter any shape, pick your units, and get instant sq ft, sq yd, sq m, acres, and cost. No signup required.
Whether you are sizing laminate for a bedroom or quoting a full renovation, this room square footage calculator handles the math so you can focus on the job. Once you have your numbers, Invoice Mama makes it easy to turn your square footage figures into a professional renovation or flooring invoice.
How to Calculate Square Footage
Three steps - same workflow as the calculator above
- 1
Pick the right shape
Rectangles and squares cover most rooms. Use circle for round patios, triangle for gable ends, trapezoid for bay windows, or border shapes for frames and walkways.
- 2
Measure and enter dimensions
Use a tape measure and record length, width, diameter, or height. Each field has its own unit dropdown, so you can mix feet and inches if that is how you measured.
- 3
Review totals and add waste
Check sq ft, sq yd, and sq m at once. Turn on multi-room mode for whole-house totals, then add a waste factor before you order materials or send a quote.
Square Footage Formulas for Every Shape
Reference table - all dimensions convert to feet before the formula runs
Shape | Formula | Variables |
|---|---|---|
| Rectangle | A = l × w | l = length, w = width |
| Square | A = s² | s = side length |
| Circle | A = π × (d ÷ 2)² | d = diameter |
| Triangle (3 sides) | A = √(s(s−a)(s−b)(s−c)) | a, b, c = sides; s = semi-perimeter |
| Triangle (base × height) | A = ½ × b × h | b = base, h = perpendicular height |
| Trapezoid | A = ½ × (a + b) × h | a, b = parallel sides, h = height |
| Rectangle border | A = (L×W) − (l×w) | Outer and inner length/width |
| Circle border | A = π(r_outer² − r_inner²) | Outer and inner radius from diameter |
| Parallelogram | A = b × h | b = base, h = perpendicular height |
| Sector | A = ½ × r² × θ | r = radius, θ = angle in radians |
Unit Conversion Reference
How linear measurements convert to feet before area is calculated
Unit | To convert to feet | Example |
|---|---|---|
| Inches | ÷ 12 | 48 in = 4 ft |
| Feet | × 1 | 10 ft = 10 ft |
| Yards | × 3 | 5 yd = 15 ft |
| Centimeters | ÷ 30.48 | 304.8 cm ≈ 10 ft |
| Meters | × 3.28084 | 3 m ≈ 9.84 ft |
Area outputs also convert automatically: multiply sq ft by 144 for sq in, divide by 9 for sq yd, multiply by 0.092903 for sq m, and divide by 43,560 for acres. That covers the most common square footage to square yards and square meters to square feet questions in one place.
Common Room Size Reference Chart
Average square footage by room type - your house may vary
Room type | Typical size (sq ft) | Notes |
|---|---|---|
| Primary bedroom | 130 – 200 | 12×14 to 14×16 is common in newer builds |
| Secondary bedroom | 100 – 144 | Often 10×10 or 10×12 |
| Living room | 180 – 350 | Open floor plans can push 400+ sq ft |
| Kitchen | 100 – 200 | Galley kitchens run smaller; islands add footprint |
| Full bathroom | 35 – 100 | 5×8 minimum; master baths are larger |
| Half bath (powder) | 18 – 35 | Usually 3×6 or 4×5 |
| Two-car garage | 400 – 576 | 20×20 to 24×24 typical |
| Home office | 80 – 150 | Converted bedrooms often land near 120 sq ft |
| Dining room | 120 – 200 | Formal dining may be separate from kitchen |
| Laundry room | 35 – 80 | Closet-style to full utility room |
How to Measure Square Footage of a Room
Practical tips from the tape measure to the order form
Start at one corner and measure wall to wall at the longest points. For carpet, measure into closets and alcoves. Round up to the nearest inch, it is better to have a little extra material than to come up short mid-install. If a room has a bay window or nook, treat it as a separate rectangle and add the areas together, or use multi-room mode and let the calculator sum everything.
How to Calculate the Square Feet of a Home
Whole-house totals without a spreadsheet
Walk the house room by room. Label each space (primary bed, hall bath, kitchen) and enter dimensions in multi-room mode. The grand total updates in real time as you add rows. For real estate listings, compare your number against ANSI guidelines: count only finished, heated, above-grade living area. Garages and unfinished basements usually stay off the total unless your MLS rules say otherwise.
Flooring and Carpet Installation
Worked example with real numbers
You are installing LVP in a 14 ft × 18 ft living room (252 sq ft) and a 12 ft × 12 ft bedroom (144 sq ft). Base total: 396 sq ft. Add 12% waste for plank cuts and transitions: 396 × 1.12 = 443 sq ft to order. At $3.25 per sq ft, material runs about $1,440. Use our tile calculator for grout and thinset on ceramic jobs, then send the client a line-item quote through the free estimate maker.
Painting and Drywall
Worked example - wall area from floor dimensions
A 12 ft × 14 ft room with 9 ft ceilings has 468 sq ft of wall area before subtracting doors and windows. Subtract one standard door (21 sq ft) and two windows (24 sq ft) and you are near 423 sq ft of paintable surface. Most paint covers 350–400 sq ft per gallon per coat, so two coats needs alot of careful measuring, but roughly three gallons. Our drywall calculator goes further with sheet counts if you are hanging new board.
Real Estate and Home Appraisal
ANSI / Fannie Mae livable area basics
Appraisers measure exterior dimensions and subtract walls, stairs, and non-livable space. Finished attics and basements count only when they meet ceiling-height and access rules. A 2,100 sq ft ranch on a listing might measure differently than your tape total, and that is normal. Use this tool for renovation and material estimates; rely on a licensed appraiser for official GLA on a purchase or refinance.
Landscaping and Outdoor Projects
Worked example - sod for a backyard
A backyard roughly 40 ft × 55 ft is 2,200 sq ft. Sod farms often quote per square yard, so divide by 9: about 244 sq yd. Add 8% for trimming around beds and edges: 2,376 sq ft total. A circular patio 16 ft in diameter adds another 201 sq ft. Use the circle shape for that section, then add it in multi-room mode for one combined order.
Commercial Construction and Office Space Planning
Worked example - tenant fit-out
A 3,200 sq ft office suite might split into open workspace (1,800 sq ft), four private offices (400 sq ft total), two conference rooms (600 sq ft), and a break room (400 sq ft). Carpet tile is often ordered with 5–7% waste in open plans. Enter each zone as a row, set quantity for identical offices, and export your total for a flooring bid or lease exhibit, then invoice the GC from the same numbers in Invoice Mama. If zones share a wall, measure each space seperately anyway so your order quantity stays honest.
How to Add a Waste Factor
See base area and adjusted area side by side before you order
Waste covers cut pieces, pattern matching, and mistakes. Straight hardwood might need 10%; diagonal tile often needs 15% or more. Enter your percentage in the optional waste field. Results show raw square footage and adjusted square footage separately so you can compare what you measured versus what you should buy. It is a simple step that prevents the most common ordering error on flooring jobs.
Frequently Asked Questions
Square footage formula, conversions, and real-world measuring
How do I calculate square footage of a room?
Measure the room length and width in feet, then multiply them together. A 12 ft by 14 ft bedroom is 168 square feet. For irregular shapes, break the room into rectangles, calculate each section, and add the totals. Our calculator handles rectangles, L-shapes via multi-room mode, and ten other shapes with automatic unit conversion.
How do I calculate square footage of a house?
Measure each room or zone separately, then add every area together for the total livable square footage. Use multi-room mode to list bedrooms, bathrooms, kitchen, and living areas row by row with a running grand total. Exclude garages, unfinished basements, and open porches unless your local listing rules say otherwise.
How many square feet is a 12×12 room?
A 12 by 12 room is 144 square feet because 12 × 12 = 144. That equals 16 square yards or about 13.38 square meters. At a common flooring waste factor of 10%, you would order roughly 158 sq ft of material to cover the same room with cuts and spare tiles included.
How do I convert square footage to square yards?
Divide square feet by nine to get square yards. One square yard equals nine square feet. For example, 270 sq ft ÷ 9 = 30 sq yd. Carpet and some turf products are priced per square yard, so this conversion matters when you compare quotes from different suppliers.
How do I calculate square footage for flooring?
Measure each room length and width, multiply for area, then add every room total. Add a waste factor of 10–15% for straight layouts or up to 20% for diagonal tile and herringbone patterns. Enter your price per square foot or square yard to see an estimated material cost before you order.
What is included in a home's square footage for real estate?
ANSI and Fannie Mae guidelines count finished, heated, above-grade living area that is accessible from the main house. Basements, garages, attics, and open porches are usually excluded unless they are finished to the same standard and included per local MLS rules. Always confirm with your appraiser or agent.
How do I measure square footage of an irregular or L-shaped room?
Divide the space into simple rectangles or squares. Measure each section, calculate its area, and add the results. In multi-room mode, add one row per section and the calculator totals everything automatically. For curved walls, approximate with a rectangle or use the sector shape for pie-slice areas.
How many square feet are in an acre?
One acre equals 43,560 square feet. To convert acres to square feet, multiply by 43,560. A half-acre lot is 21,780 sq ft. Landscapers and land buyers use this conversion constantly when comparing parcel sizes or estimating sod, seed, and mulch coverage for large outdoor projects.
How do I add a waste factor when ordering flooring or tile?
Calculate the base square footage first, then multiply by one plus your waste percentage. For 10% waste on 200 sq ft: 200 × 1.10 = 220 sq ft to order. Straight plank flooring often needs 10%, while diagonal tile may need 15% or more. Our calculator shows base area and adjusted area side by side.
How do I calculate price per square foot?
Divide the total project cost by the square footage covered. If flooring materials cost $1,320 for 240 sq ft installed, the price per square foot is $5.50. Reverse the math by entering your per-unit price in the calculator to estimate total material cost from measured area plus optional waste.
Related Free Calculators & Tools
From measurement to invoice - the full contractor workflow
- Tile CalculatorEstimate tile counts, grout, and boxes from square footage with layout waste built in.
- Drywall CalculatorSheet counts for walls and ceilings with door and window deductions.
- Decking CalculatorBoard counts and fasteners from deck dimensions and board width.
- Concrete CalculatorCubic yards and bags for slabs, pads, and outdoor hardscape pours.
- Gravel CalculatorTons, cubic yards, and cost for driveways, paths, and drainage trenches.
- Slope CalculatorRise, run, and percent grade for ramps, driveways, and drainage layout.
- Free Estimate MakerTurn your square footage and material costs into a sendable client estimate.
- Invoice GeneratorBill the job with professional line items once the work is done.
You measured the space, now get paid for it. Invoice Mama turns your square footage estimate into a professional flooring or renovation invoice in seconds.