Square Footage Calculator

The Square Footage Calculator is an essential tool for any DIY project involving floors, walls, ceilings, landscaping, or construction. Knowing the exact area of a surface is the foundation of every material estimate — whether you're buying flooring, paint, sod, mulch, tiles, or drywall. This calculator handles the four most common shapes found in home and garden projects: rectangles, triangles, circles, and trapezoids.

Square footage is the standard unit of area measurement in the United States and Canada for residential and commercial spaces. Every material sold by area — flooring, roofing, carpet, siding, insulation — is priced and packaged in square-foot quantities. Miscalculating your area even slightly can mean coming up short at the worst moment or dramatically over-buying and wasting money. This tool eliminates that guesswork by computing area instantly from your measured dimensions.

The rectangle mode handles the most common scenario: a room, wall, or patio with four right-angle corners. Simply enter the length and width. For square spaces, enter the same value for both dimensions. The triangle mode is useful for gable walls, triangular garden beds, or any space with one diagonal edge — it applies the classic formula ½ × base × height. The circle mode uses the radius (half the diameter) and the formula π × r² to compute circular areas such as round patios, garden ponds, or decorative medallions. The trapezoid mode handles spaces where two sides are parallel but different lengths — common in tapered rooms, driveways, and certain roof sections.

Beyond raw area, this calculator instantly converts your result to square meters and square yards. This is particularly useful when comparing materials sourced from different countries (European tiles measured in m², carpet sold in sq yd), ensuring you're always comparing apples to apples.

The optional cost field takes your calculated area and multiplies it by a price-per-square-foot figure to give an instant material estimate. Input the price from your local supplier or retailer, and the calculator does the rest. This is ideal for quick budget checks before heading to the store.

For complex floor plans that combine multiple shapes — say, a living room with a bay window alcove — measure each sub-area separately and add the results. Keeping a running total of these sub-areas on paper or in a notes app alongside this calculator gives you a complete area map of your project. Accurate measurement is the most important step in any home improvement project, and this calculator makes that step fast, reliable, and format-flexible.