Area Calculator
Calculate area for common shapes: rectangle, circle, triangle, trapezoid, ellipse, and sector.
I use the rectangle and circle versions constantly for home improvement planning. How much flooring for a room. Whether a circular rug fits. How much grass seed for a lawn. Having all the shapes in one place without switching between calculators or doing geometry from scratch saves real time.
Quick reference: Rectangle = length x width. Circle = pi x radius squared. Triangle = 0.5 x base x height. These three cover the majority of real-world area calculations.
Common unit conversions for area
1 square foot = 144 square inches. 1 square yard = 9 square feet. 1 acre = 43,560 square feet. 1 hectare = 10,000 square meters = 2.47 acres. For flooring and painting projects, square feet is the standard US unit. For landscaping and land measurement, acres are typical. This calculator outputs in square units matching your input — apply these conversions as needed.
Irregular shapes
For rooms with alcoves, L-shapes, or irregular footprints, break the shape into rectangles and triangles, calculate each area separately, then sum them. Alternatively, measure the bounding rectangle and subtract the areas of excluded sections. This divide-and-conquer approach works for any shape that can be decomposed into simpler ones.
Frequently asked questions
How do I account for waste when ordering flooring?
Add 10% for straight-lay flooring and 15% for diagonal or herringbone patterns. This covers cuts at walls and edges, damaged boards, and pattern matching. Order more rather than less — getting an exact match from a later batch is not guaranteed due to dye lot variation.