Square Footage Calculator
Add multiple rooms or areas — rectangles, triangles, and circles — and instantly get your total floor area in square feet, square metres, and square yards.
How It Works
Each shape uses a standard area formula:
Rectangle (most rooms): Area = Length × Width. Measure the longest wall (length) and the perpendicular wall (width) in feet or metres.
Triangle (bay windows, alcoves, angled corners): Area = ½ × Base × Height. The base is the widest edge and the height is the perpendicular distance from that base to the opposite corner.
Circle (round rooms, curved patios): Area = π × radius². The radius is half the diameter (the widest measurement across the centre).
To find a total floor area, simply add each room's area together. If you measured in feet, your totals are in square feet (ft²). Divide by 10.764 to convert to square metres (m²), or divide by 9 to convert to square yards (yd²).
Example: A living room measuring 15 ft × 12 ft = 180 ft². A triangular alcove with base 6 ft and height 4 ft = ½ × 6 × 4 = 12 ft². Total = 192 ft² = 17.84 m² = 21.33 yd².
For flooring or wallpaper projects, always add 10 % to the total to allow for cuts, waste, and pattern matching.
Frequently Asked Questions
How do I measure an irregular room?
Break the room into simple shapes — rectangles, triangles, or circles — and add them together using this calculator. For an L-shaped room, split it into two rectangles, calculate each, and add the results. This is the standard method used by flooring professionals.
What is the difference between square feet and square metres?
1 square metre = 10.764 square feet. To convert ft² to m², divide by 10.764. To convert m² to ft², multiply by 10.764. Most North American measurements use ft², while the rest of the world uses m².
How many square feet do I need for flooring?
Calculate your total room area in square feet, then add 10 % for waste and cuts (or up to 15 % for diagonal or herringbone patterns). For tiles or planks with pattern repeats, check the manufacturer's recommended overage, which can be 15–20 %.
How do I calculate wallpaper rolls needed?
Measure the perimeter of the room and multiply by the ceiling height to get the total wall area in ft². Subtract door and window areas, then add 10–15 % for pattern matching. Divide by the coverage per roll (typically 30–35 ft²) to get the number of rolls.
Can I mix metric and imperial rooms in one calculation?
Use the unit toggle to set all rooms to the same unit system before calculating. If your measurements are mixed, convert them first: 1 foot = 0.3048 metres, 1 inch = 2.54 cm.