Square Footage Calculator
Add multiple rooms to calculate total square footage for your home, renovation project, or floor plan. Results update instantly.
How to Calculate Square Footage
Multiply length × width for each rectangular room and add the totals together. Always measure at the widest points. Don't subtract for furniture, built-ins, or islands — flooring runs beneath these. Measure closets separately and add them to the room total.
For L-shaped rooms: stand at the inside corner of the L, divide the space into two rectangles, measure each, and add both areas. For triangular spaces: base × height ÷ 2.
How to Measure a Floor Plan's Square Footage
For a full floor plan, measure each room individually — including hallways and closets. Add all finished spaces together. Exclude garages, unfinished basements, and areas with ceilings under 7 feet; these don't count as livable square footage for real estate purposes.
For open floor plans where kitchen flows into dining, measure the entire combined space as one large rectangle rather than trying to divide it. If the shape is irregular, measure the longest length and width, calculate as a rectangle, then subtract any obvious cutouts.
| Space Type | Include in sq ft? | Notes |
|---|---|---|
| Bedrooms | Yes | Include closets |
| Living / dining / kitchen | Yes | Measure combined open areas as one |
| Hallways | Yes | Measure length × width |
| Finished basement | Sometimes | Depends on ceiling height and local standards |
| Unfinished basement | No | Not counted as livable sq ft |
| Attached garage | No | Listed separately in real estate |
| Covered porch / sunroom | Sometimes | Only if heated and finished |
How to Measure Irregular Rooms
| Room Shape | How to Calculate |
|---|---|
| Rectangle | Length × Width |
| L-shape | Divide into 2 rectangles, add both areas |
| Triangle / angled corner | Base × Height ÷ 2 |
| Room with closet | Measure room + closet separately, add totals |
| Open plan (kitchen + dining) | Measure the full combined space as one rectangle |
| Bay window | Add as separate rectangle to main room |
Common Room Sizes — Quick Reference
| Room Type | Small | Average | Large |
|---|---|---|---|
| Primary bedroom | 130 sq ft | 200 sq ft | 300+ sq ft |
| Secondary bedroom | 90 sq ft | 130 sq ft | 180 sq ft |
| Living room | 200 sq ft | 280 sq ft | 400+ sq ft |
| Kitchen | 80 sq ft | 120 sq ft | 200 sq ft |
| Dining room | 120 sq ft | 160 sq ft | 250 sq ft |
| Full bathroom | 35 sq ft | 50 sq ft | 80 sq ft |
| Primary bath | 60 sq ft | 100 sq ft | 150+ sq ft |
| Walk-in closet | 25 sq ft | 45 sq ft | 100 sq ft |
Average Home Square Footage by Type
| Home Type | Typical Range | US Average |
|---|---|---|
| Studio / 1BR apartment | 400–750 sq ft | ~550 sq ft |
| 2BR apartment | 700–1,100 sq ft | ~900 sq ft |
| Starter home (2BR) | 900–1,400 sq ft | ~1,200 sq ft |
| Mid-size home (3BR) | 1,400–2,200 sq ft | ~1,800 sq ft |
| Larger home (4BR) | 2,200–3,500 sq ft | ~2,700 sq ft |
| New construction avg. | — | ~2,300 sq ft |
Square Footage Waste Factors by Project
Square footage is the starting point for nearly every renovation material estimate. After calculating your area, apply the appropriate waste factor before ordering.
| Project | Base Measurement | Waste Factor to Add |
|---|---|---|
| Tile (straight lay) | Floor sq ft | +10% |
| Tile (diagonal / herringbone) | Floor sq ft | +15–20% |
| LVP / hardwood flooring | Floor sq ft | +5–8% |
| Carpet | Floor sq ft | +10% |
| Paint (walls) | Perimeter × ceiling height | Subtract doors/windows |
| Wallpaper (no pattern) | Wall sq ft | +10% |
| Wallpaper (large pattern repeat) | Wall sq ft | +35% |
| Hardwood (herringbone) | Floor sq ft | +15% |
Frequently Asked Questions
How do I calculate square footage of an L-shaped room? Divide the L into two rectangles at the inside corner. Measure each separately, calculate each area, then add them together.
Do I include walls when calculating square footage? No — square footage is floor area only. For paint and wallpaper, calculate wall area separately: perimeter × ceiling height, minus doors and windows.
Should I measure inside or outside dimensions? Always inside dimensions for interior projects — from wall surface to wall surface at floor level. Outside dimensions include wall thickness and will overestimate your usable space.
How accurate do I need to be? Within a few inches is fine for renovation projects. For real estate or permit purposes, measure to the nearest inch. For flooring, materials are typically ordered in boxes — rounding up is built into the process.