Square Footage Calculator

Use this free square footage calculator to measure any room, floor, garden, roof, or warehouse in seconds. Enter your dimensions, pick a shape — rectangle, circle, triangle, or trapezoid — and calculate area accurately in feet, inches, yards, meters, or centimeters, plus get an estimate of the total cost for flooring, tile, carpet, or concrete. Built to save time, get a precise quantity of materials, and meet any project requirement.

What This Square Footage Calculator Does

A square footage tool turns a length and width measurement into a total area expressed in square feet, square meters, square yards, or square centimeters. Whether you're a homeowner planning new carpet, a contractor pricing concrete, a landscaper estimating a garden bed, or a renter sizing up an apartment, this free area tool gives you an accurate answer in seconds — without any spreadsheet math.

This tool supports five shapes: rectangle, multi-room (irregular / L-shaped layout), circle, triangle, and trapezoid. Each input accepts feet, inches, yards, meters, or centimeters, so you can measure with whichever tape you have on hand. Add a price per square foot and the calculator estimates your material cost — with an optional waste percentage for cuts, mistakes, and pattern matching.

How to Use the Square Footage Calculator

The tool above is built around the most common real-world measurements for floor area, wall area, and outdoor projects. Pick a tab that matches the shape of your space and follow these steps:

For a single rectangular room

1. Measure the length and width of the floor with a tape measure.
2. Type both numbers into the calculator and choose your unit of measurement — feet, inches, yards, meters, or centimeters.
3. (Optional) Add the ceiling height if you want the total wall area for painting.
4. (Optional) Enter a price per square foot and pick a waste percentage.
5. Click Calculate square footage to see the total area in ft², m², and yd², plus your estimated material cost.

For multiple rooms or an L-shaped room

Use the Multi-room tab. Break the floor plan into separate rectangles, enter the length and width of each one, and the calculator adds them together. This is exactly how a contractor would quantify the total square footage of an irregular layout or a whole apartment.

For circles, triangles, and trapezoids

Switch to the matching shape tab and enter the required dimensions. The calculator handles the geometry for you — useful for round patios, pie-slice garden beds, gable roof sections, or a trapezoid driveway.

Square Footage Calculator Formulas (Every Shape)

The math behind an area tool is straightforward once you know which formula matches your shape. Here are all five, with the measurement units that go into each calculation:

Rectangle and square footage formula

This is the most common calculation in any area measurement. A room 15 ft long and 12 ft wide is 15 × 12 = 180 sq ft. The same formula works for any rectangle — a wall, a flat roof section, a driveway, or a warehouse bay.

Circle square footage formula

For a circular patio with a 14 ft diameter, the radius is 7 ft and the area is 3.14159 × 7² = 153.94 sq ft.

Triangle square footage formula

Use the base (the bottom edge) and the perpendicular height (not the slanted side). A triangle with a 12 ft base and 8 ft height is (12 × 8) ÷ 2 = 48 sq ft.

Trapezoid square footage formula

A trapezoid has two parallel sides of different lengths. If those bases measure 10 ft and 14 ft and the perpendicular height is 8 ft, the area is ((10 + 14) ÷ 2) × 8 = 96 sq ft.

Worked Examples with the Square Footage Calculator

Square Footage from Inches, Yards, and Meters

If you measured your room in something other than feet, you have two options: convert each dimension to feet first and then multiply, or select the correct unit in the calculator and let it convert for you.

• Inches: divide each measurement by 12 to convert to feet. A wall 144 inches long is 144 ÷ 12 = 12 ft. The product of two measurements in inches divided by 144 also gives square feet directly.
• Yards: multiply by 3 to convert to feet, since 1 yard = 3 feet. One square yard equals 9 square feet.
• Meters: multiply by 3.28084 to convert to feet. One square meter equals 10.7639 square feet.
• Centimeters: divide by 30.48 to convert to feet. Useful for measurements taken with a metric tape.

For background on the unit itself, see Wikipedia's article on the square foot and the National Institute of Standards and Technology's SI unit reference.

Square Footage Conversions Table

How to Estimate Flooring, Tile, Carpet, and Paint Costs

Once the square footage calculator gives you a total area, multiply by the price per square foot to estimate your project cost. The tool can do this automatically — just type a price into the optional field. A few rules of thumb for accurate material needs:

• Always add 5–10% waste for straight cuts, and 10–15% for diagonal patterns or tile borders. The calculator includes a waste-percentage dropdown so you can pick the right buffer.
• Tile and carpet are usually sold per square foot, but some carpet is still priced per square yard — remember that 1 sq yd = 9 sq ft when comparing quotes.
• Hardwood and laminate planks are priced per square foot per box. Round up to the next full box.
• Concrete is sold by the cubic yard. If you have a slab, calculate square footage first, then multiply by thickness in feet (4 inches = 0.333 ft) to get cubic feet, and divide by 27 to get cubic yards. For a full breakdown, use our companion concrete calculator.
• Paint is estimated from wall area, not floor area. Multiply each wall's length by its ceiling height, add them up, and plan on roughly 350 sq ft of coverage per gallon for one coat.

Common Uses for a Square Footage Tool

A square footage calculator saves time across dozens of everyday projects. Some of the most common use cases:

• Home improvement: flooring, tile, carpet, hardwood, laminate, vinyl, baseboards, and paint.
• Real estate: measuring a property, apartment, condo, or rental unit for listings and pricing per square foot.
• Construction and contractors: pricing concrete slabs, roofing, drywall, and insulation.
• Landscaping and gardening: sod, mulch, paver patios, and garden bed area measurements.
• Painting and installation: wall area, trim length, and wallpaper coverage.
• Commercial spaces: warehouse layout, retail floor plan, restaurant seating area, and office maintenance pricing.
• Property tax and HOA: verifying recorded square footage of a house, condo, or lot.

Tips for Accurate Square Footage Measurement

• Measure twice. A small error in one dimension is multiplied across the entire area calculation.
• Use the longest tape you can. Joining multiple short measurements introduces error at every break.
• Round to the nearest inch. Avoid eyeballing fractions — the calculator handles decimals precisely.
• For irregular rooms, sketch the floor plan on paper and divide it into rectangles before you start measuring. That's the fastest way to quantify total square footage of an L-shape.
• For round areas, measure across the widest point to get the true diameter.
• Subtract built-ins. For accurate flooring quotes, subtract the footprint of permanent islands, fireplaces, or fixed cabinetry that you won't be flooring under.

For deeper background on area measurement in general, see Wikipedia's overview of area.

Square Footage Calculator FAQs

Common questions about calculating square footage for rooms, flooring, irregular shapes, and different units of measurement.

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Last updated: July 2026 · Estimates from this area tool are for planning purposes only. Always confirm measurements and material quantities with a qualified contractor or supplier before purchasing.