Square footage (sq ft or ft²) is the standard unit of area measurement used primarily in the United States, Canada, and the United Kingdom. It represents the area of a space measured in square feet — calculated by multiplying the length by the width of a rectangular or square space. Our square footage calculator makes this calculation instant and effortless.
Understanding square footage is essential for homeowners, contractors, real estate agents, interior designers, and DIY enthusiasts. Whether you're buying flooring, painting walls, listing a property, or planning a renovation, knowing the exact area saves time, money, and prevents costly material waste.
In real estate, square footage directly impacts property valuation. Appraisers use comparable sales per square foot to determine market value. A difference of even 100 sq ft can change a home's value by thousands of dollars. Contractors rely on accurate measurements to bid projects competitively — underestimating means lost profit, overestimating means lost bids.
How to Calculate Square Footage
The formula depends on the shape of your space. Each shape below has its own area formula:
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Rectangle / Square
Area = L × W
Example: A room 12 ft long × 10 ft wide
12 × 10 = 120 sq ft
📌 Common Uses: Rooms, homes, offices, land lots, flooring, paint estimation
💡 Tip: For irregular walls, measure the longest length & width — the rectangle formula still works as a close estimate
📐 Quick Estimate: 12×12 room = 144 sq ft → add 10% waste = 158 sq ft flooring needed. For paint, measure wall perimeter × height (minus doors/windows).
💰 Material Cost: 200 sq ft area × $5/sq ft = $1,000. With 10% waste: 220 sq ft × $5 = $1,100. Use our cost estimator above!
💡 Tip: Base A and Base B must be parallel to each other. The height is measured perpendicularly between them
📐 How to Measure: Measure both parallel sides (A & B) with a tape measure. Then measure the perpendicular distance between them (h). A 5 ft + 7 ft bases × 6 ft height = 36 sq ft.
🏗️ Practical Use: For trapezoidal house lots: if A = 40 ft, B = 60 ft, h = 100 ft → area = 5,000 sq ft. Good for estimating sod, gravel, or paving needs for irregular plots!
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Ellipse (Oval)
Area = π × a × b
Example: An oval pool with semi-major a = 10 ft, semi-minor b = 6 ft
💡 Tip: Semi-major (a) is half the longest diameter. Semi-minor (b) is half the shortest diameter. Measure both full diameters and divide by 2
📐 Using Full Diameters: Area = π × (D_long/2) × (D_short/2) = (π × D_long × D_short) ÷ 4. Oval pool 12 ft × 8 ft = π × 6 × 4 = 75.4 sq ft.
🎯 Pool Cover Estimator: For an oval pool cover, add 2 ft extra on each side. 12×8 ft pool → 16×12 ft cover ≈ 151 sq ft. Always overestimate for covers!
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Pentagon
Area = ¼ × √(5(5+2√5)) × s²
Example: A pentagonal garden with side s = 4 ft
¼ × √(5(5+2√5)) × 4² ≈ 27.53 sq ft
📌 Common Uses: Pentagon-shaped structures, garden beds, decorative elements, pavilions
💡 Tip: This formula works for regular pentagons (all sides equal). If your pentagon is irregular, divide it into triangles and calculate each separately
📐 Alternative Method: A pentagon = 5 equal triangles. Area ≈ 1.72048 × s². For s = 4 ft: 1.72048 × 16 = 27.53 sq ft. Same result with less complex math!
🎯 Quick Reference: s = 3 ft → 15.5 sq ft. s = 5 ft → 43 sq ft. s = 8 ft → 110 sq ft. s = 10 ft → 172 sq ft. Perfect for estimating pentagonal pavilion or deck areas.
💡 Tip: A regular hexagon is made of 6 equilateral triangles. You can also calculate using: Area = (3√3 × s²) ÷ 2
📐 Alternate Formula: Area = 2.598 × s². A hexagon with side s = 3 ft: 2.598 × 9 = 23.38 sq ft. The apothem (center to side midpoint) = s × √3 ÷ 2 ≈ 2.598 ft.
🎯 Quick Reference: s = 2 ft → 10.4 sq ft. s = 4 ft → 41.6 sq ft. s = 6 ft → 93.5 sq ft. s = 12 ft → 374 sq ft. Great for hexagonal gazebo or tile pattern estimation!
📏 Common Room Sizes — Pre‑Calculated Areas
10′ × 10′100 sq ft9.3 m²
10′ × 12′120 sq ft11.1 m²
12′ × 12′144 sq ft13.4 m²
12′ × 14′168 sq ft15.6 m²
12′ × 16′192 sq ft17.8 m²
14′ × 14′196 sq ft18.2 m²
15′ × 15′225 sq ft20.9 m²
15′ × 20′300 sq ft27.9 m²
16′ × 16′256 sq ft23.8 m²
16′ × 20′320 sq ft29.7 m²
18′ × 20′360 sq ft33.4 m²
20′ × 20′400 sq ft37.2 m²
20′ × 30′600 sq ft55.7 m²
20′ × 40′800 sq ft74.3 m²
30′ × 40′1,200 sq ft111.5 m²
40′ × 60′2,400 sq ft223 m²
Area = Length (ft) × Width (ft) — for rectangular spaces
For example, a room that is 12 feet long and 10 feet wide has a square footage of 120 sq ft (12 × 10 = 120). Our calculator supports multiple units — feet, meters, and yards — and converts between them automatically. You can also enter inches for precise measurements.
How to Measure a Room
Use a tape measure or laser distance measurer
Measure the length from one wall to the opposite wall
Measure the width between the remaining two walls
For irregular-shaped rooms, split the area into rectangles and measure each section separately, then add them together using our Multiple Rooms mode
Always measure in feet for direct sq ft results, or use meters for square meters
Our inches input lets you enter precise measurements like 12 ft 6 in for accurate results
When Do You Need Square Footage?
Real Estate: Property listings always include total square footage — it directly affects property value and pricing
Flooring: Calculate how much tile, hardwood, carpet, or vinyl you need — always buy 10% extra for waste
Paint: One gallon of paint typically covers ~350 sq ft. Calculate wall area (wall length × height) minus doors and windows
HVAC: Heating and cooling capacity is measured in BTUs per square foot. A 1,000 sq ft home needs roughly 20,000 BTUs
Construction: Estimate material costs for drywall, concrete, roofing, and siding based on area
Interior Design: Furniture placement and room layout decisions depend on accurate floor area
Square Feet vs Square Meters vs Square Yards
Different regions use different units. Here's how they compare:
1 sq ft = 0.0929 sq meters = 0.1111 sq yards
1 sq meter = 10.764 sq ft = 1.196 sq yards
1 sq yard = 9 sq ft = 0.8361 sq meters
Our calculator automatically converts between all three units, so you get the results you need instantly, regardless of which unit you start with.
How to Estimate Material Cost
Once you know the square footage, simply multiply by the price per square foot of your material. For example, if hardwood flooring costs $5 per sq ft and your room is 200 sq ft, the material cost is $1,000. Our built-in material cost estimator does this calculation automatically — just enter the price per square foot.
Frequently Asked Questions
1. What is square footage and why is it important?
Square footage is the area of a space measured in square feet. It's critically important for real estate valuation, construction material estimation, flooring purchases, paint calculations, HVAC sizing, and interior space planning. Accurate square footage ensures you buy the right amount of materials and price properties correctly.
2. How do I calculate square footage of a room?
Measure the length and width of the room in feet using a tape measure. Then multiply the length by the width. For example, a room that is 15 ft long and 12 ft wide = 180 sq ft. For irregular rooms, divide them into rectangles, calculate each separately, and add the totals. For circular spaces, measure the radius and use π × r².
3. How to convert square feet to square meters?
Multiply the square footage by 0.0929 to get square meters. For example, 500 sq ft × 0.0929 = 46.45 sq m. Our calculator handles this conversion automatically — just switch the unit to "Meters" and it will show results in both units.
4. How do I calculate the square footage of a circle?
For a circular space, measure the radius (distance from center to edge). Then use the formula: Area = π × radius². For example, a circle with a 10 ft radius has an area of 314.16 sq ft (3.14159 × 100). Use our Circle mode for quick calculations.
5. How much flooring do I need for a 12×12 room?
A 12 ft × 12 ft room is 144 sq ft. However, you should always order extra to account for waste, cuts, and mistakes. Add 10% for straight layouts (≈158 sq ft) or 15% for diagonal/patterned layouts (≈166 sq ft). Use the Multiple Rooms mode in our calculator to tally all rooms at once.
6. How do I estimate material cost for my project?
Once you know the total square footage, multiply it by the price per square foot of your chosen material. Our calculator has a built-in material cost estimator — just enter the price per sq ft and it instantly shows the total cost. For example, 200 sq ft at $5/sq ft = $1,000. Always add 10-15% extra for waste.
7. Is this calculator free to use?
Yes! Our Square Footage Calculator is completely free to use with no limits. You can calculate single rooms or multiple rooms, switch between feet/meters/yards, enter inches, estimate material costs, save your calculations locally, and share results — all at no cost.