Square Footage Calculator — Free Online Area Tool

How to Use the Square Footage Calculator

1. Select the measurement unit: Choose from feet, meters, inches, centimeters, or yards using the dropdown menu. All calculations automatically convert to both square feet and square meters regardless of the input unit you select.
2. Enter length and width: Type the length and width of the rectangular area. The calculator accepts decimal values for precise measurements. The result updates instantly as you type, showing the area in both square feet (ft²) and square meters (m²) along with the formula used.
3. Use multi-room mode (optional): For calculating the total area of multiple rooms or sections, scroll down to the "Multi-Room Calculator" section. Click "Add Room" to create entries for each space. Give each room a descriptive name, enter its length and width, and the individual and total areas are displayed automatically.
4. Remove rooms as needed: Click the "Remove" button next to any room to delete it from the multi-room calculation. The total updates instantly.

The calculator starts with default values of 12 × 10 feet (a typical small bedroom) and includes two pre-loaded rooms in the multi-room section. Modify all values freely to match your specific measurements.

Square Footage Formulas

Variables Explained

• Length: The longer dimension of the rectangular area. In practice, length and width are interchangeable since multiplication is commutative (12 × 10 = 10 × 12).
• Width: The shorter dimension of the rectangular area. Together with length, it defines the rectangular region whose area is being calculated.
• ft² (square feet): The standard unit of area measurement in the US customary system. One square foot is the area of a 1-foot by 1-foot square (144 square inches).
• m² (square meters): The standard metric unit of area. One square meter is the area of a 1-meter by 1-meter square. Used internationally for real estate, construction, and scientific applications.
• Conversion factor 10.7639: There are approximately 10.7639 square feet in one square meter. This conversion factor is derived from the relationship 1 meter = 3.28084 feet, squared.

Step-by-Step Example

Calculate the square footage of a room measuring 14 feet 6 inches by 11 feet 3 inches:

1. Convert to decimal feet: 14 ft 6 in = 14 + 6/12 = 14.5 ft; 11 ft 3 in = 11 + 3/12 = 11.25 ft
2. Multiply: 14.5 × 11.25 = 163.13 square feet
3. Convert to square meters: 163.13 / 10.7639 = 15.15 square meters

The room has 163.13 square feet (15.15 m²) of floor area. For flooring, add 10% waste: 163.13 × 1.10 = 179.44 square feet of material needed.

Practical Examples

Example 1: Amanda's New Flooring Project

Amanda is replacing the flooring in three rooms of her home. She measured each room and needs to calculate the total area to order hardwood flooring at $8.50 per square foot (including installation).

• Living Room: 18 × 14 = 252 sq ft
• Master Bedroom: 15 × 12 = 180 sq ft
• Home Office: 10 × 11 = 110 sq ft
• Total: 252 + 180 + 110 = 542 sq ft
• With 10% waste: 542 × 1.10 = 596.2 sq ft to order
• Total cost: 596.2 × $8.50 = $5,067.70

Amanda needs to order approximately 597 square feet of hardwood flooring for a total cost around $5,068. She can use our multi-room calculator to add all three rooms and get the total area instantly, then manually add 10% for waste before ordering.

Example 2: Brian's Lawn Seeding

Brian needs to reseed his rectangular backyard that measures 45 feet by 60 feet. The grass seed he selected recommends 3 pounds per 1,000 square feet for overseeding.

• Yard area: 45 × 60 = 2,700 sq ft
• Seed needed: (2,700 / 1,000) × 3 = 8.1 pounds
• Seed comes in 5-pound bags at $24.99 each: needs 2 bags
• Total seed cost: 2 × $24.99 = $49.98

Brian needs 2 bags of grass seed (10 pounds total) for his 2,700 square foot yard. He will have about 1.9 pounds left over, which he can save for spot repairs. For larger landscaping projects, converting to acres may be useful: 2,700 sq ft ÷ 43,560 = 0.062 acres.

Example 3: Patricia's Apartment Comparison

Patricia is comparing two apartments. Apartment A lists its size as 75 square meters and costs $1,800/month. Apartment B is listed as 850 square feet at $1,650/month. She needs to compare price per square foot.

• Apartment A: 75 m² × 10.7639 = 807.29 sq ft at $1,800/month
• Apartment A price: $1,800 / 807.29 = $2.23 per sq ft per month
• Apartment B: 850 sq ft at $1,650/month
• Apartment B price: $1,650 / 850 = $1.94 per sq ft per month

Despite appearing more expensive, Apartment B is actually cheaper per square foot ($1.94 vs $2.23). It is also 43 square feet larger. Patricia gets more space for less money with Apartment B. Square footage comparison is essential when apartment listings use different unit systems.

Example 4: Greg's Tile Order

Greg is tiling his bathroom floor (8 × 6 feet) and shower walls (three walls, each 3 feet wide by 7 feet tall). He needs to calculate the total tile area.

• Floor: 8 × 6 = 48 sq ft
• Shower walls: 3 walls × 3 × 7 = 63 sq ft
• Total tile area: 48 + 63 = 111 sq ft
• With 15% waste (tile requires more waste for cuts): 111 × 1.15 = 127.65 sq ft
• Tile boxes cover 10 sq ft each: ⌈127.65 / 10⌉ = 13 boxes

Greg needs 13 boxes of tile to cover 111 square feet with a 15% waste allowance. The extra waste percentage for tile (vs 10% for flooring) accounts for cuts around edges, corners, fixtures, and breakage during installation. For the perimeter measurements needed for trim tile, try our perimeter calculator.

Unit Conversion Reference Table

Tips and Complete Guide

Measuring Rooms Accurately

Accurate measurements are the foundation of reliable square footage calculations. Use a quality tape measure at least 25 feet long for most rooms. Measure at floor level, not along walls that may bow or lean. For the most accurate results, take measurements at multiple points along each wall and use the average. Always measure in the same unit (do not mix feet and inches in your notes). Record measurements immediately and label them on a simple sketch. For rooms with fixtures like built-in cabinets, decide whether to include or exclude them based on your project needs.

Square Footage for Real Estate

In real estate, square footage typically refers to the gross living area (GLA) measured from the exterior walls. This includes all finished, heated living spaces on above-grade floors. Garages, unfinished basements, attics, and porches are usually excluded from GLA but may be listed separately. Price per square foot is a key metric for comparing properties: divide the sale price by the square footage. Be aware that different listing services may measure differently, so verify significant square footage claims with your own measurements or a professional appraiser.

Material Estimation Guide

Different materials require different waste allowances above the calculated square footage. Hardwood and laminate flooring: add 10% for straight installations, 15% for diagonal patterns. Tile: add 10-15% for standard layouts, 20% for complex patterns. Carpet: add 5-10% (less waste due to flexible material). Paint: one gallon covers 350-400 sq ft per coat, plan for 2 coats. Wallpaper: add 15-20% for pattern matching. Sod: add 5% for trimming edges. Always purchase all material from the same batch to ensure color consistency across the project.

Understanding Price Per Square Foot

Price per square foot is the standard metric for comparing real estate values, construction costs, and material prices. For home construction, costs range widely: $100-$150/sq ft for basic builds, $150-$250/sq ft for mid-range, and $250-$500+/sq ft for luxury. Renovation costs typically run 50-75% of new construction on a per-square-foot basis. Commercial spaces use the same metric but also factor in "usable" vs "rentable" square footage (rentable includes your share of common areas like lobbies and hallways, typically 15-25% more than usable).

Common Mistakes to Avoid

• Mixing measurement units: If length is in feet and width in inches, you must convert to the same unit before multiplying. A room that is 12 feet by 120 inches is 12 × 10 = 120 sq ft, not 12 × 120 = 1,440.
• Confusing linear and square measurements: You cannot compare 10 feet with 10 square feet. One is a length (line), the other is an area (surface). Ordering 100 linear feet of flooring for a 100-square-foot room will likely not be enough.
• Forgetting waste allowance: Never order exactly the calculated square footage of material. Always add at least 10% for waste. Running short mid-project means delays and potentially mismatched materials from a different production batch.
• Not accounting for room shape: Most rooms are not perfect rectangles. Measure each section of an irregular room separately. A bump-out or alcove might add 10-20 square feet that a single length-times-width calculation would miss.
• Doubling the conversion factor: When converting square units, remember the conversion factor itself is squared. 1 meter = 3.281 feet, but 1 square meter = 10.764 square feet (3.281²), not 3.281 square feet.

Frequently Asked Questions