Last updated: May 2026
Calculate floor area for any room shape — add multiple rooms to get a running total.
Room Shape
Common Room Size Reference
| Room | Typical Range (sq ft) | Notes |
|---|---|---|
| Small Bedroom | 70 – 120 sq ft | Fits a twin or full bed |
| Master Bedroom | 150 – 250 sq ft | King bed + furniture |
| Living Room | 200 – 400 sq ft | Average US home |
| Kitchen | 100 – 200 sq ft | Galley to open plan |
| Bathroom | 40 – 100 sq ft | Half bath to full bath |
| Dining Room | 100 – 200 sq ft | Seats 4–8 comfortably |
| Single-Car Garage | 200 – 280 sq ft | ~12 × 20 ft minimum |
| Two-Car Garage | 400 – 600 sq ft | ~20 × 22 ft standard |
Rectangle: Area = Length × Width
Triangle: Area = (Base × Height) ÷ 2
Circle: Area = π × r² (where r = radius). If you enter the diameter, r = diameter ÷ 2.
L-Shape: Area = (L1 Length × L1 Width) + (L2 Length × L2 Width). Divide the room into two non-overlapping rectangles.
Unit conversions: 1 sq ft = 0.0929 m² = 0.1111 sq yd. If using meters, all results are displayed in m², sq ft, and sq yd.
Square footage is the primary metric for comparing homes, apartments, and commercial spaces in the US. It directly affects pricing, property taxes, and rental rates. A 1,200 sq ft apartment and a 900 sq ft apartment with the same rent per square foot differ by 33% in space — but that difference isn't always obvious from a listing photo.
It also drives material estimates for flooring, tile, paint, and carpet. Measure your rooms correctly and you avoid two problems: buying too little (which means a second trip to the store and mismatched dye lots) and buying too much (wasted money). Always add 10–15% overage for cuts and waste.
| Room | Typical Range | Notes |
|---|---|---|
| Master bedroom | 200–250 sq ft | With or without en suite |
| Secondary bedroom | 120–180 sq ft | Standard double occupancy |
| Living room | 250–400 sq ft | Open-plan can be larger |
| Kitchen | 100–175 sq ft | Galley vs island layouts vary |
| Full bathroom | 40–60 sq ft | Tub, toilet, vanity |
| Studio apartment | 350–600 sq ft | All-in-one living space |
| 1-bedroom apartment | 600–900 sq ft | Varies by city/era |
| Average US home (2024) | ~2,280 sq ft | New single-family construction |
Does square footage include closets and bathrooms?
In real estate listings, square footage typically includes all finished indoor space — closets, bathrooms, hallways, and stairwells. It does not include garages, unfinished basements, or outdoor areas like porches (unless they're enclosed and climate-controlled). When comparing listings, verify whether the number follows ANSI Z765 standards or is a looser estimate.
How do I measure an irregular-shaped room?
Break the room into regular shapes (rectangles, triangles, half-circles) and calculate each section's area separately. Add them all together. The L-Shape option in this calculator handles the most common case. For more complex shapes, sketch it on paper, divide into rectangles, and measure each section independently.
How much does it cost per square foot to build a house?
National average construction costs in the US range from $150 to $400+ per square foot depending on finish level, location, and current material costs. A basic new home in a lower-cost area might come in at $120–$150/sq ft; a custom home with high-end finishes in a major metro can exceed $500/sq ft. These figures change significantly year to year.
How many square feet of flooring do I need for a 12x12 room?
A 12 ft × 12 ft room is 144 sq ft. With a standard 10% waste factor, you'd order 159 sq ft. For diagonal installation, use a 15% waste factor: 166 sq ft. Round up to the nearest box size when purchasing — most flooring comes in boxes covering 20–25 sq ft each.
What's the difference between square feet and linear feet?
Square feet measure area (two dimensions: length × width). Linear feet measure a single straight dimension — useful for baseboards, trim, and gutters where you only care about length, not coverage area. A room with 48 linear feet of walls and 144 sq ft of floor area are two different measurements of the same room.