How do I find the square footage of an odd-shaped room?

Break it into rectangles, calculate each area, and add them together. For an L-shaped room, split it into two rectangles at the corner.

How much extra material should I buy?

Add about 10% for waste, cuts, and pattern matching on flooring and tile — more (15%) for diagonal layouts or highly patterned material. Round up to whole boxes or units.

Square Footage Calculator

Q: How do I calculate square footage?

Multiply length by width in feet. A room 12 feet by 10 feet is 12 × 10 = 120 square feet. For a space in inches, divide each dimension by 12 first, or divide the final square inches by 144.

Find the area of a room or space from its dimensions — in feet, inches, or metres — and optionally the total cost at a price per square foot.

Total area

—

With waste allowance

—

In square metres

—

In square yards

—

Estimated cost

—

How to calculate square footage

Area (sq ft) = Length (ft) × Width (ft)
Square inches ÷ 144 = square feet · Square metres × 10.764 = square feet

Worked example

A 12 ft × 10 ft room = 120 sq ft. Add a 10% waste allowance for flooring → order for about 132 sq ft.

Odd shapes and buying materials

For L-shaped or irregular rooms, split the space into rectangles, calculate each, and add them up (run this calculator once per rectangle). Always buy extra for flooring and tile — about 10% for straight layouts, 15% for diagonal or patterned installs — because cuts and mistakes happen, and dye lots can differ between later orders. Round up to whole boxes. For specific materials, see the paint, concrete, and mulch calculators, which convert area into gallons, cubic yards, and bags.

Frequently asked questions

How do I calculate square footage?

Length × width in feet. 12 × 10 = 120 sq ft.

How do I find the area of an odd-shaped room?

Split it into rectangles, calculate each, and add them.

How much extra should I buy?

~10% for waste (15% for diagonal/patterned), rounded up to whole units.

Related calculators

Last reviewed: July 2026.