Parallelogram Square Footage Calculator
Enter your measurements below to get the area of a parallelogram in square feet, square metres, square yards and acres. The live preview draws the parallelogram to scale as you type, labelled on a measured grid, and you can drag its handles to change the measurements.
Area = Base × Height
Live scale preview
The shape is drawn to scale and relabelled as you type.
An example to start from. Drag a handle or type a measurement and it becomes yours.
Worked example
A parallelogram with base 12 ft, height 9 ft works out at 108 square feet.
| Unit | Area |
|---|---|
| sq ft | 108 |
| m² | 10.03 |
| sq yd | 12 |
| sq in | 15,552 |
| acres | 0.002479 |
When to use the parallelogram calculator
A parallelogram is a rectangle that leans. Both pairs of opposite sides are parallel, but the corners are not right angles. Diagonal parking bays, slanted driveways, angled decks, and rooms in houses built to follow a street line rather than a grid are all parallelograms — as is each repeat in a herringbone or diagonal tile layout.
The formula is base × height, exactly as for a rectangle. A parallelogram with a 16 ft base and a 9 ft perpendicular height covers 144 square feet, the same as a 16 × 9 rectangle: leaning a shape over changes how it looks but not how much floor it covers.
Why the slanted side is not used
The area depends on how far apart the two parallel sides are, not on how far the shape leans. The slanted side is always longer than the perpendicular gap, so using it overstates the area — and the more acute the angle, the worse it gets. At 45 degrees the error is about 41%, which on a 500 square foot deck is over 200 square feet of material you did not need.
Measure square to the base. If you cannot get a clean perpendicular, measure the two diagonals and the four sides and split the shape into two triangles instead, using the three-sides triangle calculator on each.
Ordering material for an angled space
Every board, tile or paver meeting the two angled edges needs a mitre cut, and the offcut is usually unusable. Add 15% waste rather than the 10% you would use on a rectangular room of the same area — the extra is entirely down to those two edges.
Frequently asked questions
How do I calculate the square footage of a parallelogram?
Multiply the base by the perpendicular height — not by the sloping side. A parallelogram with a 16 ft base and a perpendicular height of 9 ft is 144 square feet, exactly the same as a 16 ft by 9 ft rectangle. Leaning a rectangle over changes its shape but not its area, as long as the height stays the same.
Why is the slanted side not used in the calculation?
Because area depends on how far apart the two parallel sides are, not on how far the shape leans. Using the sloping side always overstates the area, and the more acute the angle the worse the error gets — at 45 degrees it is out by about 41%. Measure the gap between the parallel sides square to them and use that.
Where do parallelogram areas come up?
Diagonal parking bays, slanted driveways, angled decks and rooms in houses built to follow a street line rather than a grid. They also appear in herringbone and diagonal tile layouts, where each repeat is a parallelogram — which is part of why a diagonal lay wastes more material than a straight one.
Other shapes
A space that is not a parallelogram can nearly always be split into two or three of these and added together.
- Circle calculator
- L-Shaped Room calculator
- Rectangle calculator
- Circle Sector calculator
- Square calculator
- Trapezoid calculator
- Triangle calculator
- Triangle (Three Sides) calculator
To add several spaces into one figure, use the multi-room square footage calculator. To turn this area into an order quantity, see the material calculators.
New to the math? The square footage formula for every shape explains the calculation behind each of these tools.