The Floor Plan Square Footage Calculator calculates the total floor area of a home or floor plan.
Add up to six rooms (length × width each) to get a total, or use the whole-house mode: the main footprint plus an optional wing, multiplied by the number of floors. Results are shown in square feet and square meters.
Floor Plan Square Footage Calculator
Total square footage of a floor plan or whole house by adding up rooms — or from an L-shaped footprint and number of floors.
Formula
Rooms: A = L₁W₁ + L₂W₂ + … + L₆W₆
Whole house: A = (main L × main W + wing L × wing W) × floors
How the Calculation Works
Step 1: Measure each room (or read the dimensions from the floor plan).
Step 2: Multiply length by width for each one.
Step 3: Add them together. For a house, multiply the footprint by the number of floors.
Variables Explained
| Input | Meaning |
|---|---|
| Room length, width | Wall-to-wall dimensions of each room |
| Main footprint | Length and width of the main rectangle of the house |
| Wing | An extra rectangle (for an L-shaped house), 0 if none |
| Floors | Number of stories with the same footprint |
Example Calculation
Adding rooms
Given: 15 × 12, 12 × 11, 10 × 10 and 8 × 6 ft rooms
Result: 180 + 132 + 100 + 48 = 460 ft²
Whole house
Given: 40 × 30 ft main block plus a 12 × 10 ft wing, 2 floors
Footprint: 1,200 + 120 = 1,320 ft²
Result: 1,320 × 2 = 2,640 ft²
Common Area Conversion Table
| Unit | Equivalent |
|---|---|
| 1 m² | 10.7639 ft² |
| 1,000 ft² | ≈ 92.9 m² |
Dimensions Explained
Room sum vs official square footage
Adding room measurements gives the interior floor area. Official living-area figures (for appraisals, listings or plans) are often measured to the outside of exterior walls and follow specific local standards on what to include, such as stairs, garages or unfinished spaces. Your totals may differ.
Irregular rooms
For rooms that aren’t rectangles, work out their area with the Odd-Shaped Room calculator and add it as a single “room” with the same area.
Frequently Asked Questions
How do I calculate the square footage of a house?
Add the area of every room, or multiply the footprint by the number of floors.
Do I include hallways and closets?
For flooring, yes. For official listings, follow your local measurement standard.
Does a garage count in square footage?
Usually not in living area, but include it if you’re estimating flooring or construction.
How do I calculate an L-shaped house?
Enter the main rectangle and the wing separately.
Why is my total different from the listing?
Listings often measure exterior dimensions, which include wall thickness.