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Square Footage Calculator —
rooms, shapes & material cost.
Add multiple rooms or areas in any shape — rectangle, triangle, circle, or trapezoid. Select your measurement unit, enter an optional cost per square foot, and add a waste percentage for accurate flooring or material estimates. All calculations update in real time.
Settings
Measurement & cost
Recommended 10–15% for most flooring installations.
Total area
≈ 51.28 m²
With 10% waste:
607.2 sq ft
3 rooms
Area
≈ 23.41 m²
Formula
18 × 14 = 252 ft²
45.7% of total
Area
≈ 15.61 m²
Formula
14 × 12 = 168 ft²
30.4% of total
Area
≈ 12.26 m²
Formula
12 × 11 = 132 ft²
23.9% of total
Measurement guide
How to calculate square footage for any room or space.
Square footage (sq ft) is the standard measurement of floor area in the United States, Canada, and much of the English-speaking world. It is used in real estate listings, material estimates (flooring, tile, carpet, paint), construction bids, and building permits. Knowing the correct square footage of a space is the starting point for every home improvement project.
Rectangle: the most common shape
Most rooms are roughly rectangular. Measure the length of one wall and the width of the adjacent wall, both in feet. Multiply them:
A room that is 14 feet long and 12 feet wide has 14 × 12 = 168 square feet. Measure from wall to wall, not from skirting board to skirting board, the difference is small but consistent professional practice is to measure to the longest points.
Triangle areas
Triangular spaces appear in rooms with angled ceilings, A-frame structures, bay window recesses, and corner nooks:
The height is the perpendicular distance from the base to the opposite apex, not the slant length of the angled wall. If you have a right-angled triangle (common in corner areas), the two shorter sides are the base and height.
Circular and semicircular spaces
Circular rooms (rotundas, turrets), semicircular bays, and arched alcoves use the circle formula:
Measure the radius (distance from the centre to the wall) rather than the diameter. For a semicircle, compute the full circle area and halve it (or just halve the radius before squaring, but the correct approach is full circle ÷ 2).
Trapezoid areas
Trapezoids occur in rooms where two opposite walls are parallel but different lengths, often found in older homes, attic conversions, and irregularly shaped plots:
Measure both parallel walls (Base 1 and Base 2) and the perpendicular distance between them (Height). For a standard kitchen with one 12-ft wall and one 10-ft wall 9 feet apart: ½ × (12 + 10) × 9 = 99 sq ft.
L-shaped and irregular rooms
Most complex spaces can be broken into simpler shapes. An L-shaped room is simply two rectangles. Add each as a separate room in this calculator and the total is computed automatically. For a room with a bay window, calculate the main rectangle plus a rectangle or trapezoid for the bay.
For very irregular spaces, sketch the outline on grid paper and count squares or break the shape into as many simple pieces as needed. More pieces = more accuracy.
Unit conversions at a glance
| From | To sq ft | Example |
|---|---|---|
| Square inches | ÷ 144 | 144 in² = 1 sq ft |
| Square feet | × 1 | 1 sq ft = 1 sq ft |
| Square yards | × 9 | 1 sq yd = 9 sq ft |
| Square metres | × 10.764 | 1 m² = 10.764 sq ft |
| Square centimetres | ÷ 929 | 929 cm² = 1 sq ft |
Flooring material costs and waste allowances
Once you have the total square footage, add a waste/overage percentage to account for:
- Cuts and offcuts: Every installation produces waste at edges, corners, and doorways.
- Pattern matching: Wood, tile, and carpet with repeating patterns require additional material to align the pattern across seams.
- Future repairs: Keeping 5–10% extra is invaluable if a tile cracks or a plank needs replacing years later.
| Material type | Recommended waste |
|---|---|
| Carpet | 5–10% |
| Hardwood / laminate flooring | 7–10% |
| Ceramic or porcelain tile | 10–15% |
| Stone / natural tile | 10–15% |
| Luxury vinyl plank (LVP) | 10% |
| Mosaic tile (complex patterns) | 15–20% |
| Paint (walls) | 10% (double for porous surfaces) |
What affects cost per square foot?
The "cost per square foot" figure varies enormously depending on the material, quality, and regional labor rates:
- Carpet: $1–$6 material only; $3–$12 installed.
- Laminate flooring: $1–$5 material; $3–$8 installed.
- Hardwood flooring: $3–$12 material; $6–$18 installed.
- Ceramic tile: $0.50–$7 material; $5–$14 installed.
- Luxury vinyl plank: $2–$7 material; $3–$10 installed.
- Marble / natural stone: $5–$40+ material; $10–$50+ installed.
Always get at least three quotes from local contractors. Material prices fluctuate with supply chains, and labor rates vary significantly by region.
Tips for accurate measurement
- Use a laser distance measurer for large or awkward spaces — they're accurate to ±1–2mm over 30+ metres.
- Account for doorways and closets. Include walk-in closets in the floor plan; exclude fixed structures like built-in cabinetry islands when ordering flooring only for open floor space.
- Measure twice. Record dimensions immediately and double-check before ordering materials — returns are often impossible once cut.
- Match your unit to the product. If flooring is sold by the square yard, know your sq ft / 9 before heading to the store.
Disclaimer
Cost estimates are illustrative and based solely on the values you enter. Actual project costs depend on installation, subfloor preparation, adhesives, trim, and regional labor rates. Always consult a licensed contractor before purchasing materials.