Square Foot (ft²) - Unit Information & Conversion

Quick Answer

What is a square foot? A square foot (ft²) is the area of a square measuring 1 foot (12 inches or 30.48 cm) on each side, equal to exactly 0.09290304 square meters or 144 square inches. It's the standard unit for home sizes in the US, Canada, and UK—a typical 2,000 square foot home equals 185.8 m². One square foot is about the size of a standard 12"×12" floor tile. Real estate listings, construction blueprints, flooring estimates, and HVAC calculations use square feet throughout the English-speaking world. Use our area converter for quick square foot conversions.

Quick Comparison Table

Area (sq ft)	Everyday Equivalent	Square Meters	Square Inches
1 ft²	12"×12" floor tile	0.0929 m²	144 in²
10 ft²	Small bathroom rug (3'×3')	0.929 m²	1,440 in²
100 ft²	Small bedroom (10'×10')	9.29 m²	14,400 in²
400 ft²	Studio apartment	37.2 m²	57,600 in²
1,000 ft²	Small house or apartment	92.9 m²	144,000 in²
2,000 ft²	Typical US single-family home	185.8 m²	288,000 in²
3,500 ft²	Large house	325.2 m²	504,000 in²
43,560 ft²	One acre	4,047 m²	6,272,640 in²

Definition and Standards

The square foot is defined as the area of a square with sides measuring exactly one international foot:

1 ft² = (1 foot)² = (12 inches)² = (0.3048 meters)²

Precise Equivalents

• 1 ft² = 144 in² (exactly)
• 1 ft² = 1/9 yd² = 0.1111... yd² (exactly)
• 1 ft² = 0.09290304 m² (exactly, by 1959 definition)
• 1 ft² = 929.0304 cm² (exactly)
• 1 ft² = 92,903.04 mm² (exactly)
• 1 acre = 43,560 ft² (exactly)
• 1 square mile = 27,878,400 ft² (exactly)

International Foot Standard (1959)

The International Yard and Pound Agreement of 1959 defined the international foot as precisely 0.3048 meters, resolving slight differences between the US survey foot and the British imperial foot. This definition makes:

1 square foot = (0.3048 m)² = 0.09290304 m² (exactly)

Before 1959, small variations existed. The US survey foot (still used in some land surveys) is defined as exactly 1200/3937 meters, making the US survey square foot = 0.09290341... m² (about 0.0004% larger—negligible for most purposes).

Symbol Variations

The square foot is represented by multiple symbols:

• ft² (most common, scientific)
• sq ft or sq. ft. (common in real estate)
• SF (architectural drawings, construction documents)
• □′ (rare, using the foot prime symbol)

All represent the same unit.

History and Evolution

Ancient Origins: The Human Foot (3000 BCE - 1200 CE)

The foot as a length measurement dates to ancient civilizations, where it approximated the length of a human foot:

• Egyptian royal cubit: ~0.525 m, subdivided into "feet" of ~0.30 m
• Greek pous: ~0.296 m (varied by city-state)
• Roman pes: ~0.2967 m (29.67 cm)
• Medieval European feet: Varied from 0.25-0.34 m depending on region

These variations meant "square feet" were inconsistent across regions and time periods. A Roman square foot was about 88 cm² versus a medieval German square foot of up to 100 cm².

English Standardization: From Barleycorns to Royal Feet (1300-1824)

Medieval England attempted standardization through royal decrees:

• Edward I (1305): Defined the inch as "three grains of barley, dry and round, laid end to end," making a foot = 36 barleycorns
• Edward II (1324): Further refined the foot based on the royal standard at Westminster
• Weights and Measures Acts (1700s-1824): Gradually standardized the imperial foot across Britain

The Weights and Measures Act of 1824 officially defined the imperial foot and established consistency across the British Empire. This foot became the basis for square footage in British architecture, land surveying, and real estate.

American Adoption: Colonial Legacy (1600s-1959)

American colonists brought English measurement systems to the New World. After independence, the United States retained imperial units rather than adopting the metric system (despite Thomas Jefferson's advocacy for decimalization).

The US customary foot slightly diverged from the British imperial foot over time due to independent maintenance of measurement standards. By the mid-20th century, the difference was approximately 2 parts per million—tiny, but problematic for precision surveying.

The 1959 International Agreement: Ending the Confusion

The International Yard and Pound Agreement of 1959, signed by the United States, United Kingdom, Canada, Australia, New Zealand, and South Africa, established:

1 international yard = 0.9144 meters (exactly)

1 international foot = 0.3048 meters (exactly)

1 international square foot = 0.09290304 m² (exactly)

This unified the foot globally and aligned imperial units with the metric system through exact conversion factors.

Exception: The US survey foot (1200/3937 meters) remains in use for some land surveys to maintain consistency with historical surveys. This creates a US survey square foot slightly different from the international square foot—a distinction only relevant in precision surveying.

Persistence Despite Metrication (1960s-Present)

Throughout the 20th century, most countries adopted the metric system. However, square feet remain dominant in:

United States: Exclusively uses square feet for residential real estate. All home listings, construction documents, building codes, and HVAC calculations use ft². Metrication efforts failed in the 1970s.

United Kingdom: Officially metricated in 1995, requiring metric units in commerce. However, real estate continues to list properties in both square feet and square meters, with square feet often prominently displayed due to consumer preference and historical familiarity.

Canada: Officially metricated (square meters), but square footage remains common in real estate listings and construction, particularly in regions near the US border.

India, Pakistan, Bangladesh: Use square feet as the primary unit for real estate despite official metrication. Property advertisements overwhelmingly use sq ft.

Hong Kong, Singapore, Malaysia: Mixed systems. Hong Kong historically used square feet but increasingly shows square meters. Singapore mandates square meters but square feet remain understood.

The Real Estate Lock-In Effect

Square footage persists in real estate due to:

1. Consumer familiarity: Buyers understand "2,000 sq ft" intuitively from years of exposure
2. Historical data: Decades of comparable sales in square feet make valuation easier
3. Industry resistance: Realtors, appraisers, and builders resist change due to retraining costs
4. Building codes: US building codes specify minimum room sizes in square feet
5. Property taxation: Tax assessments based on square footage in many jurisdictions

Real-World Examples

Residential Room Sizes (Typical US Homes)

Room Type	Typical Size (sq ft)	Dimensions (example)	Square Meters
Walk-in closet	25-50 ft²	5'×5' to 5'×10'	2.3-4.6 m²
Half bathroom	15-25 ft²	3'×5' to 4'×6'	1.4-2.3 m²
Powder room	20-30 ft²	4'×5' to 5'×6'	1.9-2.8 m²
Full bathroom	35-60 ft²	5'×7' to 8'×10'	3.3-5.6 m²
Master bathroom	75-150 ft²	8'×9' to 10'×15'	7.0-13.9 m²
Small bedroom	80-120 ft²	8'×10' to 10'×12'	7.4-11.1 m²
Medium bedroom	120-200 ft²	10'×12' to 12'×15'	11.1-18.6 m²
Master bedroom	200-400 ft²	12'×15' to 20'×20'	18.6-37.2 m²
Living room	200-400 ft²	15'×15' to 20'×20'	18.6-37.2 m²
Kitchen	100-200 ft²	10'×10' to 12'×15'	9.3-18.6 m²
Dining room	120-250 ft²	10'×12' to 14'×18'	11.1-23.2 m²
Garage (single)	200-280 ft²	12'×20' to 14'×20'	18.6-26.0 m²
Garage (double)	400-600 ft²	20'×20' to 24'×24'	37.2-55.7 m²

Home Sizes by Type

Home Type	Typical Size (sq ft)	Square Meters	Description
Studio apartment	400-600 ft²	37-56 m²	Single room + bathroom
1-bedroom apartment	600-900 ft²	56-84 m²	Bedroom, living area, kitchen, bath
2-bedroom apartment	900-1,200 ft²	84-111 m²	Two bedrooms, 1-2 baths
Small house	1,000-1,500 ft²	93-139 m²	Starter home, 2-3 bedrooms
Medium house	1,500-2,500 ft²	139-232 m²	Typical suburban home, 3-4 bedrooms
Large house	2,500-4,000 ft²	232-372 m²	Spacious family home, 4-5 bedrooms
Luxury/McMansion	4,000-7,000+ ft²	372-650+ m²	High-end, 5+ bedrooms, multiple living areas

US statistics (2023):

• Median new single-family home: 2,261 sq ft (210 m²)
• Average new single-family home: 2,480 sq ft (230 m²)
• Trend: Growing from 1,660 sq ft (154 m²) median in 1973

Commercial Real Estate

Space Type	Typical Size (sq ft)	Square Meters	Use
Small retail shop	500-1,500 ft²	46-139 m²	Boutique, coffee shop
Medium retail	2,000-5,000 ft²	186-465 m²	Restaurant, clothing store
Large retail	10,000-50,000 ft²	929-4,645 m²	Supermarket, department store
Big-box store	50,000-200,000 ft²	4,645-18,581 m²	Walmart, Home Depot
Office suite (small)	500-2,000 ft²	46-186 m²	Startup, small business
Office floor	10,000-50,000 ft²	929-4,645 m²	Corporate floor
Warehouse (small)	10,000-50,000 ft²	929-4,645 m²	Distribution center
Warehouse (large)	100,000-1,000,000+ ft²	9,290-92,903+ m²	Amazon fulfillment center

Lease rates are typically quoted as $/sq ft/year (US) or $/sq ft/month (some markets):

• Prime Manhattan office: $80-150/sq ft/year
• Suburban office: $15-35/sq ft/year
• Retail (shopping mall): $30-100/sq ft/year
• Industrial warehouse: $5-15/sq ft/year

Land Measurements

While acres are more common for land, square feet are used for smaller parcels and lot dimensions:

• Small urban lot: 2,000-5,000 ft² (0.05-0.11 acres)
• Typical suburban lot: 7,000-15,000 ft² (0.16-0.34 acres)
• Large suburban lot: 20,000-40,000 ft² (0.46-0.92 acres)
• One acre: 43,560 ft² (exactly)
• One square mile: 27,878,400 ft² (exactly)

Example: A 0.25-acre residential lot = 10,890 sq ft (could be 90'×121' or 100'×109')

Construction Materials Coverage

Building materials are sold based on square foot coverage:

Material	Coverage per Unit	Typical Unit Cost
Carpet	Sold per sq yd (9 sq ft)	$2-10/sq ft installed
Hardwood flooring	20-25 sq ft per carton	$5-15/sq ft installed
Laminate flooring	20-30 sq ft per carton	$3-8/sq ft installed
Tile	1 sq ft per 12"×12" tile	$5-20/sq ft installed
Paint	350-400 sq ft per gallon	$30-60/gallon
Drywall	32-48 sq ft per sheet (4'×8' or 4'×12')	$1-3/sq ft installed
Roofing shingles	33 sq ft per bundle (1/3 "square")	$100-300 per 100 sq ft ("square")
Siding	Variable by type	$4-20/sq ft installed

Roofing terminology: A "square" = 100 sq ft of roof area. A 2,000 sq ft home might need 25-30 squares of shingles (accounting for roof pitch and overhangs).

HVAC Sizing Rules of Thumb

Heating and cooling systems are sized based on square footage:

Air conditioning (US):

• Rule of thumb: 1 ton (12,000 BTU/hr) per 400-600 sq ft (depending on climate, insulation)
• Hot climate (Phoenix, Miami): 1 ton per 400 sq ft
• Moderate climate (Atlanta, Kansas City): 1 ton per 500 sq ft
• Cool climate (Seattle, Boston): 1 ton per 600 sq ft

Example: A 2,000 sq ft home in Texas needs ~5 tons AC (60,000 BTU/hr)

Heating:

• Rule of thumb: 30-60 BTU/hr per sq ft (depending on insulation, climate)
• Well-insulated, mild climate: 30 BTU/hr per sq ft
• Average: 40-50 BTU/hr per sq ft
• Poorly insulated, cold climate: 60+ BTU/hr per sq ft

Common Uses

1. Real Estate Listings and Sales

Square footage is the primary metric for home valuation in the US, Canada, and UK. Property listings always specify total square footage, often breaking down:

• Total living area (heated/cooled space)
• Bedroom sizes (sq ft per room)
• Basement area (finished vs. unfinished)
• Garage (often listed separately)

Price per square foot is the key metric for comparable sales analysis:

• National US average (2025): $150-200/sq ft for new construction
• Urban markets (San Francisco, NYC): $400-1,000+/sq ft
• Suburban markets: $100-250/sq ft
• Rural markets: $80-150/sq ft

Example: A 2,000 sq ft home listed at $400,000 = $200/sq ft

2. Construction and Architecture

Blueprints, floor plans, and construction documents use square feet for:

• Floor area calculations (required for building permits)
• Material estimates (flooring, drywall, roofing in sq ft)
• Cost estimating (construction cost per sq ft)
• Zoning compliance (maximum floor area ratio, minimum room sizes)

Construction costs (2025 US averages):

• Budget home: $100-150/sq ft
• Standard home: $150-250/sq ft
• Custom home: $250-400/sq ft
• Luxury home: $400-800+/sq ft

3. Flooring and Home Improvement

Flooring materials (carpet, tile, hardwood, laminate) are purchased by the square foot. Homeowners measure room dimensions to calculate total square footage needed, adding 10-15% for waste.

Calculation example:

• Living room: 15' × 18' = 270 sq ft
• Add 10% waste: 270 × 1.10 = 297 sq ft
• Order 300 sq ft of flooring

Paint coverage: One gallon covers ~350-400 sq ft per coat (varies by surface texture). Calculate wall square footage: (Perimeter × Height) - (window/door areas).

4. HVAC System Design

Heating and cooling systems are sized in BTUs or tons, calculated based on square footage of conditioned space. HVAC contractors use Manual J load calculations that account for:

• Square footage (primary factor)
• Insulation levels (R-values)
• Window area and efficiency
• Climate zone
• Air infiltration rates

Rule of thumb: Oversimplified (1 ton/400 sq ft), but professional calculations adjust for specifics.

5. Property Taxation and Assessment

Many jurisdictions calculate property taxes partially based on square footage. Assessors measure "finished living area" to determine assessed value.

Example: A county might assess homes at $150/sq ft, so a 2,500 sq ft home has an assessed value of $375,000, with property tax = assessed value × tax rate (e.g., $375,000 × 1.2% = $4,500/year).

6. Interior Design and Space Planning

Interior designers use square footage to:

• Determine appropriate furniture sizes for rooms
• Calculate occupancy limits (building codes specify sq ft per person)
• Specify area rug sizes
• Plan layouts and circulation space

Furniture scale guidelines:

• Small bedroom (100 sq ft): Twin/full bed, nightstand, small dresser
• Medium bedroom (150 sq ft): Queen bed, two nightstands, dresser, chair
• Large bedroom (250 sq ft): King bed, full furniture set, seating area

Conversion Guide

Square Feet to Square Meters

1 ft² = 0.09290304 m² (exactly)

Formula: m² = ft² × 0.09290304

Quick approximation: m² ≈ ft² ÷ 10.764

Examples:

• 100 ft² = 9.29 m²
• 1,000 ft² = 92.9 m²
• 2,000 ft² = 185.8 m²
• 3,500 ft² = 325.2 m²

Square Feet to Square Meters converter →

Square Feet to Square Inches

1 ft² = 144 in² (exactly)

Formula: in² = ft² × 144

Examples:

• 1 ft² = 144 in²
• 10 ft² = 1,440 in²
• 0.5 ft² = 72 in²

Use case: Small surface areas (tiles, countertops, small materials)

Square Feet to Square Inches converter →

Square Feet to Square Yards

1 yd² = 9 ft² (exactly)

Formula: yd² = ft² ÷ 9

Examples:

• 9 ft² = 1 yd²
• 90 ft² = 10 yd²
• 270 ft² = 30 yd²
• 1,000 ft² = 111.11 yd²

Use case: Carpet is often sold by the square yard, so divide room sq ft by 9

Square Feet to Square Yards converter →

Square Feet to Acres

1 acre = 43,560 ft² (exactly)

Formula: acres = ft² ÷ 43,560

Examples:

• 10,890 ft² = 0.25 acres
• 21,780 ft² = 0.5 acres
• 43,560 ft² = 1 acre
• 100,000 ft² = 2.296 acres

Use case: Converting lot sizes from sq ft to acres for land sales

Square Feet to Acres converter →

Calculating Room Square Footage

For rectangular rooms:

Area = Length × Width (both in feet)

Examples:

• 10' × 12' room = 120 sq ft
• 15' × 18' living room = 270 sq ft
• 8' × 10' bedroom = 80 sq ft

For irregular shapes, break into rectangles/triangles and sum:

L-shaped room:

• Main section: 15' × 20' = 300 sq ft
• Extension: 8' × 10' = 80 sq ft
• Total: 380 sq ft

For circular/curved areas:

• Circle: Area = π × radius² = 3.1416 × (radius in feet)²
• Example: 10-foot diameter circular room = 78.54 sq ft

Common Conversion Mistakes

❌ WRONG: Adding dimensions instead of multiplying

"A 10' × 12' room is 22 square feet (10+12)."

✅ RIGHT: Multiplying length × width

"A 10' × 12' room is 120 square feet (10×12)."

Why it matters: Area requires multiplication of two dimensions, not addition. Adding gives linear feet (perimeter ÷ 2), not area.

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❌ WRONG: Confusing linear feet with square feet

"I need 100 feet of flooring for my 100 square foot room."

✅ RIGHT: Matching units to measurement type

"I need 100 square feet of flooring for my 100 square foot room (which is 10'×10')."

Why it matters: Flooring is sold in sq ft (area), not linear feet (length). Perimeter would be 40 linear feet, but you need 100 sq ft of material.

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❌ WRONG: Converting ft² to m² by converting one dimension

"A 10' × 10' room is 100 sq ft. 10 feet = 3.048 m, so 3.048 × 3.048 = 9.29 m²... wait, that's right. But doing 100 ft × 0.3048 = 30.48 m² is wrong!"

✅ RIGHT: Converting area using area conversion factor

"100 sq ft × 0.09290304 = 9.29 m². Or convert each dimension: (10 ft × 0.3048 = 3.048 m) × (10 ft × 0.3048 = 3.048 m) = 9.29 m²."

Why it matters: To convert area, use the area conversion factor (0.0929), not the length conversion factor (0.3048). Alternatively, convert each dimension separately, then multiply.

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❌ WRONG: Forgetting to square the conversion factor

"Since 1 foot = 0.3048 meters, 1 sq ft = 0.3048 sq meters."

✅ RIGHT: Squaring the linear conversion factor

"Since 1 foot = 0.3048 meters, 1 sq ft = (0.3048)² = 0.09290304 sq meters."

Why it matters: Area conversion factors are the square of linear conversion factors. Forgetting to square understates the conversion by ~70%.

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❌ WRONG: Confusing square feet with cubic feet

"My 1,000 square foot apartment has 1,000 cubic feet of space."

✅ RIGHT: Multiplying by height for volume

"My 1,000 sq ft apartment with 8-foot ceilings has 8,000 cubic feet of volume (1,000 ft² × 8 ft = 8,000 ft³)."

Why it matters: Square feet measure area (2D), cubic feet measure volume (3D). You must multiply floor area by ceiling height to get volume.

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❌ WRONG: Using approximate conversion for precise needs

"1 sq ft ≈ 0.1 m², so 2,000 sq ft ≈ 200 m²."

✅ RIGHT: Using exact conversion factor

"1 sq ft = 0.09290304 m², so 2,000 sq ft = 185.8 m² (not 200 m²)."

Why it matters: Rounding 0.0929 to 0.1 introduces a 7.6% error—significant for real estate valuations, material orders, or legal documents.