Square Footage Calculator
Calculate rectangular square footage from length and width.
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What this tool does
Calculate rectangular square footage from length and width. Both dimensions must refer to the same rectangular section.
How to use the Square Footage Calculator
- Enter or select length in ft.
- Enter or select width in ft.
- Read the calculated result; change any measurement to compare alternatives.
Formula
area=length×width
- length
- Length (ft, before metric conversion)
- width
- Width (ft, before metric conversion)
Both dimensions must refer to the same rectangular section.
Worked example
For square footage calculator, the following measurements illustrate the exact method: Length: 20; Width: 10.
Inputs
- Length20 ft
- Width10 ft
Result
- Area200 sq ft
Results explained
- Area
- Area from the formula above, expressed in sqft before metric conversion. Both dimensions must refer to the same rectangular section.
Frequently asked questions
Multiply length by width in feet; square meters use the unit toggle.
Measure two perpendicular dimensions.
Use 5–10% for simple layouts and 10–15% for diagonal cuts or complicated outlines; the allowance is editable.
Split the outline into rectangles or triangles and calculate each section separately. Do not count overlapping sections twice.
This is a purchasing estimate, not a structural design. Confirm measurements and local requirements before buying or building.