The square footage of a parallelogram is base × height, using the perpendicular height (not the slanted side). For example, a 12-foot base with a 5-foot height covers 12 × 5 = 60 square feet.
See our square footage calculator and property area guide to apply this area to rooms and parcels.
How to Calculate the Square Footage of a Parallelogram
A parallelogram is a slanted rectangle: two pairs of parallel sides, with no right angles. The calculator asks for the base and the perpendicular height — not the length of the slanted side — because that is what determines the area.
The formula
Area = base × height
The height is the straight-line distance between the two parallel sides, measured at 90° to the base.
How to measure
Measure the base along one side. Then measure the height straight across to the opposite parallel side, square to the base — use a framing square or a chalk line. Using the slanted side instead of the height overstates the area.
Worked example
An angled parking bay has a 20-ft base and is 9 ft between the parallel lines.
Area = 20 × 9 = 180 square feet.
Where this shape is used
- Angled parking and driveways: Paving and sealing angled bays.
- Slanted garden beds and lots: Plots that lean along a road or fence line.
- Diagonal tile features: Rows of tile laid on a slant.
Related shape calculators
Working with a different shape? Try the rhombus calculator, rectangle calculator, trapezoid calculator, or the kite calculator. Each one shows the formula, a worked example and unit conversions.