How this calculator works
Choose the shape that matches what you are measuring — a plain rectangle, a circle, a triangle, or a floor plan made of multiple rectangular sections added together — and enter the dimensions. The calculator returns the total area in square feet and square meters, and an estimated cost if you enter a price per square foot or square meter, useful for flooring, tile, turf or paint quotes.
The multiple-sections mode is built for irregular rooms and combined spaces: an L-shaped room, a house with an attached garage, or a yard made of a lawn plus a patio. Break the space into up to three rectangular pieces, enter each one's length and width, and leave any section you don't need blank — it's simply skipped and left out of the total rather than causing an error.
The formula
Rectangle: area = length × widthCircle: area = π × radius²Triangle: area = 0.5 × base × heightMultiple sections: total area = sum of each section's length × width1 square foot = 0.3048² = 0.09290304 square meters exactly, following the international foot definition. Cost is simply total area × the price per unit area you enter.
Worked example: a 12 ft × 10 ft room plus an 8 ft × 6 ft alcove
- Main section: 12 × 10 = 120 square feet.
- Alcove section: 8 × 6 = 48 square feet.
- Total: 120 + 48 = 168 square feet.
- At $4.50 per square foot for flooring: 168 × 4.50 = $756.
Frequently asked questions
How is square footage different from floor area shown in a listing?
Real estate listings sometimes include or exclude garages, basements and porches depending on local convention. This calculator only totals the shapes you enter — decide which spaces to include based on what you're measuring for (a flooring quote, a paint job, a legal disclosure) and add or leave out sections accordingly.
What if my room has more than three irregular sections?
Run the calculator more than once and add the totals together yourself, or combine smaller sections into one larger rectangle where the geometry allows it. Any shape can be broken into rectangles, triangles and circle segments and summed manually if needed.
Why measure a circle by radius instead of diameter?
The area formula (π × radius²) needs the radius directly. If you measured the diameter — the distance straight across — divide it by two before entering it as the radius.
Should I round up for material orders?
This calculator gives the exact geometric area. Materials like tile, flooring and turf are usually sold in fixed units and typically need a waste allowance of 5 to 10% or more on top of the exact area, especially for cuts, seams and pattern matching.
Does the cost estimate include labor?
No — the cost field is simply area multiplied by whatever price per square foot or square meter you enter. Enter a material-only price for material cost, or an all-in installed price if you have one from a quote.