Square Footage Calculator Widget

Add a square footage calculator that handles real floor plans. Readers add up to six areas, each a rectangle, circle or triangle measured in feet or metres, and see the total in square feet, square metres and square yards, with an optional cost estimate.

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<iframe src="https://a2z.tools/embed/w/square-footage-calculator" title="Square Footage Calculator by A2Z Tools" width="100%" height="840" style="border:0;width:100%" loading="lazy" allow="clipboard-write"></iframe>

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How it works

Irregular rooms and plots can usually be split into simple shapes. Each area is measured on its own - length times width for a rectangle, pi times the radius squared for a circle, half base times height for a triangle - and the areas are added. The total is converted with the exact definition 1 foot = 0.3048 metres. Switching between feet and metres converts the entered dimensions too.

Calculation method

  • Rectangle = length x width
  • Circle = pi x (diameter / 2)^2
  • Triangle = base x height / 2 (height measured at right angles to the base)
  • Total = sum of the areas, in the square of the unit the dimensions were entered in
  • 1 ft = 0.3048 m exactly, so 1 sq ft = 0.09290304 m2; 1 sq yd = 9 sq ft
  • Cost = total area x price per unit area; square feet and yards are shown to 2 decimals, square metres to 3 in the breakdown, cost to 2 decimals of the currency

Worked examples

Two rooms in feet

Inputs: Rectangle 12 ft x 10 ft plus rectangle 10 ft x 8 ft

Result: Total 200 sq ft = 18.58 m2 = 22.22 sq yd

120 + 80 = 200 sq ft; 200 x 0.09290304 = 18.580608 m2 and 200 / 9 = 22.22 sq yd.

Room with a round alcove

Inputs: Rectangle 12 ft x 10 ft plus a circle 10 ft across

Result: Total about 198.54 sq ft (18.44 m2)

The circle adds pi x 5 x 5 = 78.54 sq ft to the 120 sq ft rectangle.

Limitations

  • Only rectangles, circles and triangles; an irregular polygon has to be split into those shapes, and overlapping shapes are counted twice.
  • It does not apply any building-measurement standard (such as gross or net internal area rules) or deduct columns and fixed units.
  • No waste allowance is added to the cost estimate; add 5-10% yourself for flooring cuts.

Where publishers use it

  • Flooring, tiling and carpet shops quoting by area
  • Estate agents checking a listing's stated floor area
  • Landscapers and turf suppliers measuring lawns and beds
  • Home-renovation blogs

Questions

How do I measure an L-shaped room?

Split it into two rectangles that do not overlap, measure each, and add both as separate areas.

Should I add extra for waste?

For flooring and tiles, suppliers usually recommend adding 5% to 10% for cuts and breakage, more for diagonal layouts.

Is the metric conversion exact?

Yes. The international foot is defined as exactly 0.3048 m, so 1 sq ft is exactly 0.09290304 m2.

Can I preset the shapes?

Yes: v_unit=ft or m, v_shape1..v_shape6 (rect, circle, tri), v_a1..v_a6 and v_b1..v_b6 for the dimensions, and v_price.

How do I measure a bay window or a round patio?

Enter a round patio as a circle using its diameter. A half-round bay is half a circle, so enter it as a circle and halve that part yourself, or approximate it with a triangle and a rectangle.

Why does my listing show a different square footage?

Listings may use gross external area, include wall thickness or stairwells, or follow a local measurement standard. This widget adds only the internal shapes you measure, so it usually comes out smaller than a gross figure.

Sources

  1. Putting the Best Foot Forward: Ending the Era of the U.S. Survey Foot - National Institute of Standards and Technology (NIST) . States 1 foot = 0.3048 metre exactly (since 1959) and that the international foot replaces the U.S. survey foot from 1 January 2023.

Cite or recommend this tool

If you reference this tool in an article, course or documentation, these formats are ready to copy. They are optional - nothing is added to your site unless you paste it.

A2Z Tools Square Footage Calculator
https://a2z.tools/embed/square-footage-calculator

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