Rectangle Area
Worked example: 8 m x 5 m rectangle → 40 m^2 — press Try an example to run it live, then adjust anything.
Enter your known values, leave one input blank, and solves for the missing one. Tap a variable’s symbol to see what it means, with a typical value. Try different units for next level excitement!
Area in reverse →
Grade 10Grade 10 Math
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Rectangle Area explained
Length times width is the most fundamental area formula there is: a rectangle 4 units long and 3 units wide tiles perfectly into 4 × 3 = 12 unit squares, and counting those squares is the area. A painter uses it constantly — a wall 4 m long and 2.5 m high presents 10 m² of surface, and at a typical coverage of 10 m² per litre, that wall costs exactly one litre of paint per coat.
Every other area formula is built on this one. A parallelogram is a sheared rectangle, a triangle is half of one, and even the areas of curved shapes are found by slicing them into ever-thinner rectangular strips — the idea at the heart of integral calculus. Watch the units: multiplying two lengths gives a squared unit, so metres in means square metres out, and mixing feet with metres without converting first is the classic mistake.
Rectangle Area formula
- = Area (m²)
- = Length (m)
- = Width (m)
Missing one of these? Work it out first, then come back
- Area — Area of a Circle, Area of a Triangle
- Length — Rectangle Perimeter, Rectangle Diagonal
- Width — Rectangle Perimeter, Rectangle Diagonal