Square Footage Calculator

Planning a flooring update, estimating materials, or measuring your space? Enter your dimensions into the calculator above to get an instant square footage estimate. It works for rectangles, circles, triangles, trapezoids, and irregular shapes.

Square footage tells you how much flat surface an area covers, measured in square feet (ft²). Whether you need the total square footage of a room, a wall, or an entire house, the math starts with a few simple measurements. This guide walks through every shape and scenario so you can calculate square footage with confidence.

How to Calculate Square Footage

The basic idea is straightforward. Measure the length and width in feet, then multiply them together.

Square footage = Length (ft) × Width (ft)

For a 12×16 room, that means 12 × 16 = 192 square feet. A 20×20 room is 400 square feet. A 30×40 space is 1,200 square feet.

If your measurements are in inches, divide each number by 12 first to convert to feet. If they are in meters, multiply each by 3.281. The calculator handles these conversions automatically.

Here is the general process:

1. Choose the shape that matches your space.
2. Measure each required dimension (length, width, radius, etc.).
3. Record the measurement in feet. Use a pen and paper or your phone.
4. Enter the numbers into the calculator.
5. Read your total area in square feet.

For simple rectangular rooms, that is all you need. For circles, triangles, trapezoids, and irregular shapes, the formulas change slightly. Each one is covered below.

Calculate Area of a Rectangle Using Length, Width, and Height

Most rooms, walls, and floors are rectangles. To calculate the area, multiply the length by the width.

Area = Length × Width

A room that is 15 feet long and 12 feet wide has an area of 180 square feet. Both measurements must be in the same unit before you multiply.

When does height matter? Height comes into play when you are calculating wall surface area for paint or tile. Each wall is its own rectangle: multiply the wall's length by its height to find that wall's square footage. Add all four walls together for the total wall area.

For example, a 15×12 room with 8-foot ceilings has:

• Two walls at 15 × 8 = 120 sq ft each
• Two walls at 12 × 8 = 96 sq ft each
• Total wall area: 120 + 120 + 96 + 96 = 432 sq ft

Subtract the area of any doors and windows to get a more precise estimate for paint or tile.

Calculate Square Footage of a Circle

Circular spaces (patios, columns, round rooms) use pi and the radius.

Area = π × r²

The radius is half the diameter. If a circular patio is 20 feet across, the radius is 10 feet.

• Area = 3.1416 × 10² = 314.16 square feet

Measure the widest point across the circle to get the diameter, then divide by two. Enter that radius into the calculator and it handles the rest.

For a semicircle, divide the result by two. For a quarter circle, divide by four.

How to Calculate Square Footage of a Triangle

Triangular areas show up in gable walls, oddly shaped yards, and attic spaces.

Area = ½ × Base × Height

The base is any one side. The height is the perpendicular distance from that base to the opposite point.

A triangular section with a 16-foot base and a 9-foot height has an area of:

• ½ × 16 × 9 = 72 square feet

Make sure you measure the height at a right angle to the base, not along the sloped side.

Trapezoid Square Footage Calculation

A trapezoid has two parallel sides of different lengths. This shape appears in some room layouts, lot boundaries, and architectural features.

Area = ½ × (Base₁ + Base₂) × Height

If one parallel side is 20 feet, the other is 14 feet, and the perpendicular distance between them is 10 feet:

• Area = ½ × (20 + 14) × 10 = 170 square feet

Measure both parallel sides and the straight-line distance between them. The calculator will do the multiplication.

Calculate Square Footage for Irregular Shapes

Most real spaces are not perfect rectangles. Rooms have closets, alcoves, and L-shaped layouts. The strategy is to break the space into smaller standard shapes.

1. Sketch the floor plan on paper.
2. Divide it into rectangles, triangles, or circles.
3. Calculate each section's area separately.
4. Add all sections together for the total square footage.

Example: An L-shaped room. Split it into two rectangles. A 12×10 section plus a 6×8 section gives 120 + 48 = 168 square feet.

Rooms with closets. Measure the main room as one rectangle, then measure the closet as a second rectangle. Add them together for the full square footage. Some appraisals exclude closets, but for flooring and material estimates, include every area you plan to cover.

If a section has a curved wall, approximate it as a semicircle or quarter circle and add that area to the total.

How to Measure Square Feet in Inches, Meters, and Yards

Not every tape measure reads in feet. Here is how to convert common units before or after your calculation.

From inches to feet: Divide each measurement by 12. A room that is 144 inches long is 12 feet long. Multiply the converted length and width to get square feet.

You can also multiply inches together first, then divide the result by 144 (since 144 square inches = 1 square foot).

From meters to feet: Multiply each measurement by 3.281. Or multiply your result in square meters by 10.764 to convert to square feet.

From yards to feet: Multiply each measurement by 3. One square yard equals 9 square feet.

Quick reference:

The calculator accepts multiple units and converts automatically, so you do not need to do this math by hand.

Cost per Square Foot: Calculate the Cost of Materials

Once you know your total square footage, estimating material costs is simple. Multiply the area by the price per square foot.

Total cost = Square footage × Price per sq ft

Most building materials, flooring, paint, and landscaping products are priced per square foot or can be converted to that unit. Below are the most common categories.

Flooring Cost per Square Foot

Flooring is the most popular reason people search for a square footage calculator. Here are typical price ranges per square foot (materials only, not installation):

• Laminate: $1 to $5 per sq ft
• Hardwood flooring: $3 to $12 per sq ft
• Engineered wood: $2 to $10 per sq ft
• Bamboo: $2 to $8 per sq ft
• Vinyl plank: $1 to $5 per sq ft

Installation adds $2 to $8 per sq ft depending on the material and your region. These are ballpark estimates. Get quotes from local installers for precise pricing.

Do you actually need to order extra flooring? Yes. Order 5% to 10% extra to cover cuts, waste, and future repairs. For diagonal or pattern installations, bump that to 15%.

Tile, Carpet, and Paint per Square Foot

• Ceramic tile: $1 to $15 per sq ft depending on quality and style
• Carpet: $1 to $7 per sq ft (carpet is also sold by the square yard; divide cost per sq yd by 9)
• Paint: One gallon covers roughly 350 to 400 square feet. Divide your wall area by 375 for a quick gallon estimate

For tile, add 10% extra for breakage and cuts. For carpet, sellers typically round up to the nearest roll width, so actual material quantity may exceed your exact square footage.

Pricing Laminate, Hardwood, and Engineered Wood Flooring

Choosing between traditional hardwoods, engineered wood, and laminate affects both your budget and installation approach.

• Laminate is the most affordable. It installs as a floating floor, so labor costs are lower.
• Hardwood flooring costs more but adds resale value. It can be refinished multiple times.
• Engineered wood offers real wood appearance with better moisture resistance than solid hardwood.

To estimate total cost, enter your room's dimensions into the calculator above to get the square footage. Then multiply by the cost per square foot for your chosen material. Add 5% to 10% for waste.

For a 300 sq ft room with engineered wood at $6 per sq ft:

• Material: 300 × $6 = $1,800
• Plus 10% waste: $1,980
• Installation at $4/sq ft: $1,200
• Estimated total: $3,180

These numbers are estimates. Actual costs depend on product selection, subfloor condition, and local labor rates.

Square Footage Calculator vs. Home Depot Square Footage Tools

Home Depot and other home improvement retailers offer their own square footage tools, usually tied directly to product purchasing. Those tools are helpful when you are buying from that specific store, but they can steer you toward particular products or quantity thresholds.

A free square footage calculator like this one is store-neutral. You get a clean area estimate without upsells or brand-specific recommendations. Use it to:

• Calculate your total square footage before shopping
• Compare pricing across multiple retailers
• Estimate material needs for any project, not just flooring

If a retailer's tool gives a different number, double-check by running the same dimensions here. The math should match. Differences usually come from how waste percentage or rounding is applied.

How to Calculate Square Footage of a House

Calculating the total square footage of a house involves more than measuring one room. You need to account for every finished floor, and decide which spaces to include.

General rule: Finished, livable space counts. Most appraisals exclude garages, unfinished basements, and unfinished attics. Enclosed porches and sunrooms may or may not count depending on local standards.

The average house in the United States is roughly 2,200 to 2,500 square feet, though this varies widely by region and home type.

Which tools should you use? A tape measure (25 feet or longer), the calculator above, and a simple sketch of each floor. For large or complex homes, a laser distance measurer speeds things up.

Calculate Square Footage for Each Floor

Measure each floor separately, then add them together.

1. Sketch the floor plan for one level.
2. Break it into rectangles (and triangles or other shapes if needed).
3. Calculate each section and sum them.
4. Repeat for every finished floor.

A two-story home with 1,100 sq ft on the first floor and 900 sq ft on the second floor has 2,000 total square feet.

Include hallways, closets, and bathrooms. Exclude the garage unless your local market counts it. Stairways are typically counted on the floor where they begin.

What is usable square footage? This term refers to the space you can actually furnish and occupy. It excludes interior walls, columns, and mechanical chases. Usable square footage is always less than gross square footage. For home improvement projects, measure gross square footage so you buy enough material.

Roof and Landscaping Square Footage

Roof area is not the same as the footprint of your house. Roof pitch adds surface area. A simple multiplier based on pitch handles this:

A 1,200 sq ft footprint with a 6/12 pitch has roughly 1,342 sq ft of roof surface.

Landscaping square footage uses the same area formulas. Measure your yard, garden beds, or patio space as rectangles, circles, or irregular shapes. This calculator works for landscape projects like sod, mulch, gravel, and pavers. Multiply area by the product's coverage rate to estimate quantity.

Common Square Footage Calculation Mistakes

Small errors in measurement or math can lead to ordering too much or too little material. Watch for these frequent issues:

• Mixing units. Measuring one wall in inches and another in feet, then multiplying without converting. Always convert to the same unit first.
• Forgetting to subtract openings. When calculating wall area for paint or tile, subtract doors (roughly 21 sq ft each) and windows (roughly 12 sq ft each).
• Rounding too aggressively. Rounding 11.6 feet down to 11 feet across a large space creates a meaningful gap. Use decimals until the final answer.
• Ignoring waste. Ordering exactly the calculated amount leaves no margin for cuts, damaged pieces, or future repairs.
• Measuring at angles. Always measure perpendicular lines. Diagonal measurements inflate your numbers.
• Counting the same space twice. When breaking irregular rooms into sections, make sure sections do not overlap.

Double-check by measuring each dimension twice. If the two numbers do not match, measure a third time.

Square Feet to Square Yards and Other Conversions

Need your result in a different unit? Here are the most common conversions from square feet.

Examples:

• 450 sq ft ÷ 9 = 50 square yards
• 450 sq ft ÷ 10.764 = 41.81 square meters
• 450 sq ft × 144 = 64,800 square inches

Carpet is often sold by the square yard. Divide your square footage by 9 to get the number of square yards you need. International projects may require square meters. The calculator can handle these conversions directly, so you get results in whichever unit you prefer.