What is the formula for the Rectangle Calculator?
Rectangle Calculator: area = a × b; perimeter = 2(a+b); diagonal = √(a²+b²). Input definitions: a = First side; b = Second side. Use the selected convention throughout the calculation.
Plane geometry
Rectangle Calculator
Calculate area, perimeter and diagonal from two perpendicular side lengths. These equations require a rectangle, not an arbitrary quadrilateral.
- Explicit formulas and worked examples
- Check your inputs, then calculate
- Data is calculated in this browser only
Check the stated input format, calculation convention and limits before using the result.
Check the example inputs, then calculate. Your values stay in this browser.
Both lengths must be positive and in the same unit.
Calculation notes
Understand the Rectangle Calculator
Rectangle Calculator validates first side, second side before applying the displayed equation. Both lengths must be positive and in the same unit.
How can I reproduce the Rectangle Calculator example?
Rectangle Calculator baseline input: First side: 3; Second side: 4. Output: Area = 12; Perimeter = 14; Diagonal = 5. Substitute these values into the displayed equation to reproduce the result.
How should I interpret the Rectangle Calculator result?
- Read area with its stated unit and convention. The default example and the independent worked scenario use different inputs, so compare the assumptions before comparing the numbers.
- Change one input at a time and use the equation to explain the result; do not mix unit, grade-scale, time-zone or rounding conventions across comparisons.
What limits apply to the Rectangle Calculator?
- Both lengths must be positive and in the same unit.
- Area uses squared units, while perimeter and diagonal use length units.
Content and calculation reviewed:
Understand the calculation
How to use it and the math behind it
Four steps to check your inputs and results
- Calculate area, perimeter and diagonal from two perpendicular side lengths. These equations require a rectangle, not an arbitrary quadrilateral.
- Enter First side, Second side in the stated format. Baseline values are for reproduction.
- Check the output unit and convention: Read area with its stated unit and convention. The default example and the independent worked scenario use different inputs, so compare the assumptions before comparing the numbers.
- Change one input and compare the result. Both lengths must be positive and in the same unit. Area uses squared units, while perimeter and diagonal use length units.
Rectangle Calculator: calculation relationships
A rectangle combines two perpendicular lengths. Sides 5 and 12 give area 60, perimeter 34 and diagonal √(25+144)=13. Area counts unit squares, while perimeter and diagonal measure length. Equal perimeters do not imply equal areas; the equations do not apply to a skewed quadrilateral without right angles.
area = a × b; perimeter = 2(a+b); diagonal = √(a²+b²)
The detailed guide adds variable definitions, a reproducible example, a practice question and model limitations.
From question to result