Measure a Rectangular Area Before Ordering Materials
Use the same unit for length and width.
Measure matching dimensions
Use the same unit for length and width. Do not enter 12 feet as one value and 120 inches as the other without converting or selecting matching measurements. Record which edges were measured so you can recheck the calculation.
Multiply for area, add for perimeter
A 5-metre by 4-metre rectangle has an area of 20 square metres. Its perimeter is 18 metres. Area describes the flat surface; perimeter describes the distance around its outside edge. They use different units.
Break up irregular outlines
For an L shape, divide the outline into rectangles without overlap. Add the areas. Subtract an excluded opening only if that opening is not part of the surface you are estimating. Sketching the sections helps prevent counting a corner twice.
Separate coverage from purchase quantity
An area result does not include cutting waste, installation rules or packaging increments. Use the supplier’s stated coverage and a task-appropriate allowance to turn a measured area into an order. Verify important measurements on site.
Put it into practice
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Calculate a rectangle’s area in square feet and square metres from matching length measurements.
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