SettingsSettings for this calculationUS
Pick the shape that best matches your area.
For an irregular room, split it into rectangles (or triangles) and add the results together.
The longer side of the rectangle.
Measure the longest straight edge.
Tools needed: Tape measure
The shorter side of the rectangle.
Measure perpendicular to the length.
Tools needed: Tape measure
Total area
149.5 sq ft
- Square feet
- 149.5 sq ft
- Square yards
- 16.61 sq yd
- Acres
- 0 ac
They open the calculator with your figures already in it
Square Footage Calculator: 150 sq ft — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
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How this was calculated
Formula source(s)
- Standard geometry formulas: rectangle = L x W, circle = pi x r², triangle = 1/2 x base x height
Inputs used
- Shape
- Rectangle
- Length
- 13 ft
- Width
- 11.5 ft
- Diameter
- 19.5 ft
- Base
- 16.5 ft
- Height
- 13 ft
Intermediate steps
- Square feet
- 149.5 sq ft
- Square yards
- 16.61 sq yd
- Acres
- 0 ac
What this calculation does not cover
- Area is taken from the outline of one shape with nothing subtracted: there is no field for a kitchen island, a chimney breast, a stair opening or a structural column, so anything standing inside the measured outline is still counted as floor.
- The number returned is bare geometry with no waste, cut or overage percentage folded into it, so material ordered straight off it leaves nothing for off-cuts, pattern match or breakage.
- Two horizontal measurements multiplied give a plan area, so a pitched roof plane, a ramped driveway or a lawn falling away from the house carries more real surface than the figure shown.
- Circle mode squares half the diameter, so a tape reading two per cent out moves the answer by roughly four, and one diameter can only describe a true circle rather than an oval pond or the curve of a bay window.
- Base times height, halved, is taken on trust: nothing checks that the height was measured at a right angle to the base, so the slanted edge entered by mistake inflates the result with no warning.
- Every length field stops at 100 m (about 328 ft), which caps the acres line near 2.47 acres (1 hectare) for a rectangle and lower for the other two shapes, so a paddock or lot beyond that has to be measured in sections and totalled by hand.
Estimated cost — your price
This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.
Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.
Sources checked 2026-09-05 · in the site-wide review of 2026-09-06 · v1.0.1
Regulatory standards & verification citations1
- Standard geometry formulas: rectangle = L x W, circle = pi x r², triangle = 1/2 x base x height
Cite this page
Your workspace
Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.