What this calculator does
Square footage is the area of a space measured in square feet, found by multiplying its length by its width when the space is a simple rectangle. It is the figure asked for on flooring quotes, paint and turf calculations, real estate listings and building permits across the United States and other countries that measure area in feet rather than metres.
The calculation itself is straightforward, but it is easy to mix up a length or width entered in inches with one entered in feet, or to average two different room measurements instead of adding up separate rectangular sections. Enter length and width in feet for the section being measured, and treat an L-shaped or irregular room as separate rectangles added together.
The formula
Multiply length by width, both measured in feet, to get the area in square feet. The equivalent in square metres is also shown, using the standard conversion factor of 0.092903 square metres per square foot.
| Term | Meaning |
|---|---|
| Square footage | The area of a space in square feet: length × width. |
| Length | The longer or reference side of the rectangular area being measured, in feet. |
| Width | The other side of the rectangular area, in feet. |
The inputs explained
| Field | What to enter |
|---|---|
| Length (ft) | The length of the space, measured in feet. |
| Width (ft) | The width of the space, measured in feet. |
When to use it
Ordering flooring or carpet
Flooring is typically priced and sold by the square foot, so working out the area first, before allowing for waste and offcuts, gives a starting quantity to order against.
Comparing listed room sizes
A real estate listing or floor plan often states raw dimensions rather than a computed area, so multiplying them out gives a figure that can be compared directly against other properties.
Estimating paint or turf coverage
Paint and turf coverage is usually quoted per square foot, so knowing the area of the surface being covered is the starting point for working out how much to buy.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
Square footage at common room widths, for a range of lengths
A room 12 feet wide, at a range of lengths.
| Length | Square footage | Equivalent in square metres |
|---|---|---|
| 8 ft | 96.00 sq ft | 8.92 sq m |
| 10 ft | 120.00 sq ft | 11.15 sq m |
| 12 ft | 144.00 sq ft | 13.38 sq m |
| 15 ft | 180.00 sq ft | 16.72 sq m |
| 20 ft | 240.00 sq ft | 22.30 sq m |
| 25 ft | 300.00 sq ft | 27.87 sq m |
Square footage for a range of square rooms
A square room, with length and width kept equal, at a range of side lengths.
| Side length | Square footage | Equivalent in square metres |
|---|---|---|
| 10 ft | 100.00 sq ft | 9.29 sq m |
| 12 ft | 120.00 sq ft | 11.15 sq m |
| 15 ft | 150.00 sq ft | 13.94 sq m |
| 18 ft | 180.00 sq ft | 16.72 sq m |
| 20 ft | 200.00 sq ft | 18.58 sq m |
| 24 ft | 240.00 sq ft | 22.30 sq m |
Questions
How do I measure an L-shaped or irregular room?
Split it into simple rectangles, work out the square footage of each one separately, then add the results together. Trying to average a room’s widest and narrowest points instead of splitting it up will usually give the wrong answer.
How do I convert square footage to square metres?
Multiply the square footage figure by 0.092903, which is what this calculator does automatically. For converting an area you already know in either direction, see the dedicated square feet to square metres converter.
Should I measure wall-to-wall or to the inside of the skirting board?
For most everyday purposes, such as ordering flooring or estimating paint, wall-to-wall is close enough. Trade quotes for fitted work may specify a particular measuring convention, so check what the supplier expects before ordering materials.
Does square footage include closets and alcoves?
That depends on the convention being used. Real estate listings and building codes often have specific rules about what counts as livable or gross area; for a straightforward materials estimate, include any area you actually need to cover.
To compute area in square metres directly from a length and width, see the square metre calculator. To convert a square footage figure you already have into square metres, use the sqft to sqm converter.