Square Footage Calculator
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.
How to calculate square footage
Square inches ÷ 144 = square feet · Square metres × 10.764 = square feet
A 12 ft × 10 ft room = 120 sq ft. Add a 10% waste allowance for flooring → order for about 132 sq ft.
Split an L-shaped room into two rectangles: a 12 ft × 10 ft section (120 sq ft) plus a 6 ft × 8 ft section (48 sq ft) = 168 sq ft total. Run this calculator once for each rectangle and add the results.
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.
Typical room sizes for reference
| Room | Typical size |
|---|---|
| Bedroom | 120–200 sq ft |
| Living room | 250–400 sq ft |
| Kitchen | 150–250 sq ft |
| Bathroom | 40–100 sq ft |
| Two-car garage | 400–500 sq ft |
Common square footage mistakes
- Measuring wall-to-wall vs. usable floor space inconsistently. Including a closet in one room but not another (or excluding a fireplace hearth inconsistently) skews material orders — most suppliers expect wall-to-wall minus large fixed obstructions.
- Mixing units within one calculation. Measuring length in feet and width in inches without converting first produces a meaningless area — always convert both dimensions to the same unit before multiplying.
- Forgetting the waste allowance applies to material ordered, not the room's actual area. A 120 sq ft room stays 120 sq ft; the extra 10% only affects how much flooring or tile you buy to cover it.
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.
Should I measure wall-to-wall or exclude closets?
For flooring and painting, include closet floor space. For furniture layout or a real-estate figure, closets may be counted separately — check the convention needed.
How do I calculate square footage with mixed units?
Convert everything to the same unit first. 14'6" × 10'3" = 14.5 ft × 10.25 ft = 148.6 sq ft.
Related calculators
Last reviewed: September 2026.