Square Footage Calculator
Work out the total square footage of a floor plan: enter each room as length × width, one per line, and get the combined area in square feet and square meters, plus the total wall perimeter.
Add 5–10% for cuts and waste when ordering flooring or tile.
Formula and calculation
Worked example
Three rooms, 12×14, 10×12 and 11×13 feet: the areas are 168, 120 and 143 sq ft, so the total is 431. Room perimeters are 52, 44 and 48 ft, totalling 144.
L-shaped and irregular rooms
Split an L-shaped room into two rectangles, measure each, and give each its own line — the areas add up the same way. For a bay window or alcove, add it as a small extra room. Measuring tip that saves expensive mistakes: measure each wall at floor level and again at waist height, and use the smaller number — rooms are rarely perfectly rectangular, and paint and flooring quotes price the area you actually have.
What the results mean
- Total area
- The combined floor area of all rooms, in the units you entered.
- Also
- The same total converted to square meters (or square feet when you entered meters).
- Total wall perimeter
- The sum of each room's wall perimeter (2 × (length + width)). Useful for trim, baseboard and painting estimates — but it counts shared walls between rooms twice.
- Rooms counted
- How many room lines were counted — trailing blank lines are ignored.
- Largest room
- The floor area of the largest single room you entered.
Frequently asked questions
How do I calculate square feet of a room?
Multiply the length by the width in feet: a 12 ft × 14 ft room is 168 square feet. For several rooms, calculate each and add them — enter one room per line here and the total comes out in both square feet and square meters.
How do I convert square feet to square meters?
Multiply by 0.09290304: 500 sq ft is 46.45 m². Converting in the other direction, one square meter is 10.7639 square feet. This calculator shows both units for whatever you enter.
How much flooring should I buy for the square footage?
Add 5–10% to the area for cuts and waste — 10% for diagonal or herringbone layouts. Buy all material in one batch so the dye lot matches, and keep a spare box for repairs.
Does the perimeter count shared walls twice?
Yes. The perimeter total adds each room's full outline, so a wall between two counted rooms appears twice. For baseboard in connected rooms, deduct the doorways; for exterior trim only, measure the outside outline instead.