How it works
Pick a shape and enter its measurements. Heights are always perpendicular distances: for a triangle, parallelogram or trapezoid, measure straight across at a right angle, not along a slanted side.
For a trapezoid, a and b are the two parallel sides. For an ellipse, use the semi-axes (half the full width and half the full height). A sector is a pizza-slice part of a circle defined by its central angle.
Choose real units to see the area converted to square meters and square feet as well.
Formula
Rectangle lw · Triangle ½bh · Circle πr² · Trapezoid ½(a+b)h · Parallelogram bh · Ellipse πab · Sector (θ/360)πr²
Questions people ask
How do I find the area of an irregular room?
Split it into rectangles and triangles, find each area, and add them. An L-shaped room is two rectangles.
Why is a triangle half of base times height?
Any triangle is exactly half of a parallelogram with the same base and height, and a parallelogram's area is base × height.
How many square feet are in a square yard?
Nine, because a yard is 3 feet and 3 × 3 = 9. A square meter is about 10.764 square feet.