How Many Square Feet Is a 30x40 Room?
A 30 ft × 40 ft room equals 1,200 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 30x40 Room
| Metric | Value |
|---|---|
| Floor area | 1,200 sq ft |
| Floor area (m²) | 111.48 m² |
| Floor area (sq yd) | 133.33 sq yd |
| Perimeter | 140 ft |
| Wall area (8 ft ceiling) | 1,120 sq ft |
| Wall area (9 ft ceiling) | 1,260 sq ft |
| Wall area (10 ft ceiling) | 1,400 sq ft |
Common Uses for a 30x40 Space
- pole barn
- small warehouse
At 1,200 sq ft, this falls in the xlarge category — best suited for two-car garages, workshops, or open great rooms.
How Much Flooring Will You Need?
For a 30' × 40' room, buy enough flooring to cover 1,200 sq ft plus a waste allowance:
| Flooring Type | Waste % | Buy This Much |
|---|---|---|
| Laminate / LVP (plank) | 10% | 1,320 sq ft |
| Hardwood | 10% | 1,320 sq ft |
| Ceramic tile (straight) | 10% | 1,320 sq ft |
| Ceramic tile (diagonal) | 15% | 1,380 sq ft |
| Carpet | 10% | 1,320 sq ft (147 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 30x40 Room?
With 8 ft ceilings you'll paint about 1,120 sq ft of wall. A gallon covers ~350 sq ft, so you'll need 4 gallons per coat. Plan on two coats for a color change.
Detailed breakdown on our Paint Calculator.
Is a 30x40 Room Big?
This is a spacious footprint — think workshop, pole barn, or open-plan great rooms in larger homes.
How Much Does It Cost to Build a 30x40 Room?
At typical US rates of $150–$300 per sq ft for new construction, a 30x40 addition would cost roughly $180,000–$360,000. For remodels:
- Basic flooring replacement: $3,600–$12,000
- Mid-range remodel: $60,000–$120,000
- Full gut renovation: $120,000–$300,000
Refine with our Cost per Square Foot Calculator.
Frequently Asked Questions
How many square feet is 30x40?
30 × 40 = 1,200 square feet.
How many square meters is 30x40?
111.48 m².
How many tiles will fit in a 30x40 room?
Depends on tile size. 12"×12" tiles = 1,320 tiles (with 10% waste). See our Tile Calculator for 6", 18", and 24" sizes.
How much carpet do I need for a 30x40 room?
133.33 sq yd minimum, or 146.67 sq yd with 10% waste for cuts and seams.