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% |
Common Square Footage Mistakes
- Measuring outside dimensions for an interior project. Outside (wall-to-wall including framing) measurements can overstate a room by 5-8% versus the actual floor space you'll cover with flooring or paint. Always measure inside, surface to surface.
- Applying one waste factor to every material. Straight-lay tile needs +10%, diagonal or herringbone patterns need +15-20%, and wallpaper with a large pattern repeat can need +35%. Using a flat 10% across the board under-orders pattern-heavy materials.
- Confusing total and livable square footage when budgeting. An unfinished basement or garage counts toward "total" square footage but not "livable" — mixing the two when pricing a per-square-foot renovation quote skews the estimate.
- Forgetting closets in flooring math. Closets are easy to skip when eyeballing a room, but they still need flooring or paint. Measure and add them to the room total before applying your waste factor.
- Rounding each room individually instead of the total. Rounding up room-by-room compounds waste across a multi-room project. Sum the raw square footage first, then apply the waste factor once to the combined total.
Frequently Asked Questions
How do I calculate square footage of an L-shaped or irregular room?
Divide the space into rectangles at each inside corner. Measure each rectangle's length and width separately, calculate each area, then add them together for the total.
Do I include walls or closets when calculating square footage?
Square footage is floor area only — don't include wall thickness. Closets should be included for renovation material estimates (flooring, paint), though real estate listing standards vary by state and sometimes exclude small closets.
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 by roughly 5-8%.
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.
How is total square footage different from livable square footage?
Total square footage often includes garages and unfinished basements, while livable square footage counts only finished, climate-controlled space — the figure typically used in real estate listings.
What's the difference between square feet and square yards?
One square yard equals 9 square feet. Carpet is sold by the square yard; most other flooring and paint materials are calculated by the square foot.