How Many Square Feet Is a 15x18 Room?
A 15 ft × 18 ft room equals 270 square feet. Use the calculator below to double-check or customize with waste and cost.
Last updated:Tip: If you only have the diameter, divide by 2 to get the radius.
L-shape = two rectangles sharing a corner.
Add one row per rectangle and we'll sum them.
Key Measurements for a 15x18 Room
| Metric | Value |
|---|---|
| Floor area | 270 sq ft |
| Floor area (m²) | 25.08 m² |
| Floor area (sq yd) | 30.00 sq yd |
| Perimeter | 66 ft |
| Wall area (8 ft ceiling) | 528 sq ft |
| Wall area (9 ft ceiling) | 594 sq ft |
| Wall area (10 ft ceiling) | 660 sq ft |
Common Uses for a 15x18 Space
- family room
- great room
At 270 sq ft, this falls in the large category — sized for great rooms, master suites, or single-car garages.
How Much Flooring Will You Need?
For a 15' × 18' room, buy enough flooring to cover 270 sq ft plus a waste allowance:
| Flooring Type | Waste % | Buy This Much |
|---|---|---|
| Laminate / LVP (plank) | 10% | 297 sq ft |
| Hardwood | 10% | 297 sq ft |
| Ceramic tile (straight) | 10% | 297 sq ft |
| Ceramic tile (diagonal) | 15% | 311 sq ft |
| Carpet | 10% | 297 sq ft (33 sq yd) |
Need an exact estimate? Use our Flooring Calculator for plank count, or the Tile Calculator for boxes of tile.
How Much Paint for a 15x18 Room?
With 8 ft ceilings you'll paint about 528 sq ft of wall. A gallon covers ~350 sq ft, so you'll need 2 gallons per coat. Plan on two coats for a color change.
Detailed breakdown on our Paint Calculator.
Is a 15x18 Room Big?
This is a large room — great for primary suites, family rooms, or open-plan spaces.
How Much Does It Cost to Build a 15x18 Room?
At typical US rates of $150–$300 per sq ft for new construction, a 15x18 addition would cost roughly $40,500–$81,000. For remodels:
- Basic flooring replacement: $810–$2,700
- Mid-range remodel: $13,500–$27,000
- Full gut renovation: $27,000–$67,500
Refine with our Cost per Square Foot Calculator.
Frequently Asked Questions
How many square feet is 15x18?
15 × 18 = 270 square feet.
How many square meters is 15x18?
25.08 m².
How many tiles will fit in a 15x18 room?
Depends on tile size. 12"×12" tiles = 297 tiles (with 10% waste). See our Tile Calculator for 6", 18", and 24" sizes.
How much carpet do I need for a 15x18 room?
30.00 sq yd minimum, or 33.00 sq yd with 10% waste for cuts and seams.