Length and width
Length a + Width b
A = ab; P = 2(a+b); d = √(a²+b²)
Open calculator ↗GEOMETRY, ONE FIGURE AT A TIMERectangle.
Rectangle.
Understand every measure.
Turn two lengths into a complete picture. Four free tools, clear formulas and a little discovery along the way.
Find your calculator ↗FIGURE 072D / REFERENCE DRAWING
RECTANGLENOT TO SCALE
THE CALCULATOR DESK
Start with what you know.
4 calculators available
Diagonal and one side
Diagonal d + Known side a
b = √(d²−a²)
Open calculator ↗Area and one side
Area A + Known side a
b = A/a
Open calculator ↗Perimeter and one side
Perimeter P + Known side a
b = P/2−a
Open calculator ↗MEET THE FIGURE
A rectangle, explained.
A rectangle is a quadrilateral with four right angles. Opposite sides are equal and parallel. The two adjacent side lengths determine its area, perimeter and diagonal.
Understand the properties ↗LOOK A LITTLE CLOSER
More than a formula.
Equal perimeter does not imply equal area: different rectangles can use the same boundary length.
Do not use a sloping distance as a side. A diagonal must exceed the known adjacent side.
Explore three geometry facts ↗These tools use ideal Euclidean geometry. Every input must use the same unit. Numerical results are rounded and do not replace measurement, specialist design or safety checks. See worked examples.