Simplify Your Workflow: Search MiniWebtool.
Add Extension
Home Page > Math > Geometry Calculators > Rectangle Calculator

Rectangle Calculator

Calculate rectangle area, perimeter, diagonal, inscribed circle, circumscribed circle, and aspect ratio from any two known values. Includes interactive SVG diagram and step-by-step solutions.

Rectangle Calculator

Try these examples:

10 x 6 Golden Ratio Area 120, L=15 Diagonal 13, L=12

Embed Rectangle Calculator Widget

About Rectangle Calculator

Welcome to the Rectangle Calculator, a comprehensive geometry tool that calculates all properties of a rectangle from any two known values. Whether you know the length and width, the area and one side, the perimeter and one side, or the diagonal and one side, this calculator will find all remaining measurements including area, perimeter, diagonal, inscribed circle radius, circumscribed circle radius, and aspect ratio.

What is a Rectangle?

A rectangle is a quadrilateral (four-sided polygon) with four right angles (90 degrees each). The word comes from the Latin rectus (right) and angulus (angle). Key properties of a rectangle include:

Rectangle Formulas

Area of a Rectangle

The area represents the space enclosed within the rectangle:

Area Formula
$$A = a \times b$$

Where a is the length and b is the width.

Perimeter of a Rectangle

The perimeter is the total distance around the rectangle:

Perimeter Formula
$$P = 2(a + b)$$

Diagonal of a Rectangle

The diagonal connects opposite corners. Using the Pythagorean theorem:

Diagonal Formula
$$d = \sqrt{a^2 + b^2}$$

Inscribed Circle (Largest Circle Inside)

The largest circle that fits inside a rectangle touches the two longer sides:

Inscribed Circle Radius
$$r_{in} = \frac{b}{2}$$

Where b is the shorter side (width).

Circumscribed Circle (Smallest Circle Outside)

The smallest circle that contains the entire rectangle passes through all four corners:

Circumscribed Circle Radius
$$R = \frac{d}{2} = \frac{\sqrt{a^2 + b^2}}{2}$$

How to Use This Calculator

  1. Select calculation mode: Choose what information you know (Length + Width, Area + Side, Perimeter + Side, or Diagonal + Side)
  2. Enter your values: Input the known measurements in the appropriate fields
  3. Optionally add a unit: Specify the unit of measurement for clearer results
  4. Click Calculate: View all rectangle properties, visual diagram, and step-by-step calculations

Understanding the Results

PropertyDescription
Length (a)The longer side of the rectangle
Width (b)The shorter side of the rectangle
Area (A)Space enclosed by the rectangle (in square units)
Perimeter (P)Total distance around the rectangle
Diagonal (d)Distance from one corner to the opposite corner
Inscribed RadiusRadius of the largest circle that fits inside
CircumradiusRadius of the smallest circle containing the rectangle
Aspect RatioRatio of length to width (a:b)

The Golden Rectangle

A golden rectangle is a special rectangle whose sides are in the golden ratio:

Golden Ratio
$$\phi = \frac{1 + \sqrt{5}}{2} \approx 1.618$$

Golden rectangles are considered aesthetically pleasing and appear frequently in art, architecture, and nature. The Parthenon in Athens and Leonardo da Vinci's works feature golden rectangle proportions. This calculator tells you how close your rectangle is to the golden ratio.

Real-World Applications

Frequently Asked Questions

What is a rectangle?

A rectangle is a quadrilateral (four-sided polygon) with four right angles (90 degrees). Opposite sides of a rectangle are equal in length and parallel. The word "rectangle" comes from Latin "rectus" (right) and "angulus" (angle). A square is a special type of rectangle where all four sides are equal.

How do you calculate the area of a rectangle?

The area of a rectangle is calculated by multiplying its length by its width: Area = length x width. For example, a rectangle with length 8 units and width 5 units has an area of 8 x 5 = 40 square units. The area represents the amount of space inside the rectangle.

How do you calculate the diagonal of a rectangle?

The diagonal of a rectangle is calculated using the Pythagorean theorem: Diagonal = sqrt(length^2 + width^2). This works because the diagonal, length, and width form a right triangle. For example, a rectangle with length 8 and width 6 has a diagonal of sqrt(64+36) = sqrt(100) = 10 units.

What is the perimeter of a rectangle?

The perimeter of a rectangle is the total distance around its edges. It is calculated as: Perimeter = 2 x (length + width). For example, a rectangle with length 10 units and width 6 units has a perimeter of 2 x (10 + 6) = 32 units.

What is the golden rectangle?

A golden rectangle is a rectangle whose side lengths are in the golden ratio, approximately 1:1.618 (or more precisely, 1:(1+sqrt(5))/2). Golden rectangles are considered aesthetically pleasing and appear frequently in art, architecture, and nature. When you cut a square from a golden rectangle, the remaining rectangle is also a golden rectangle.

Can you fit a circle inside a rectangle?

Yes, the largest circle that fits inside a rectangle (inscribed circle) has a diameter equal to the shorter side of the rectangle. So the inscribed circle radius = width/2 (where width is the shorter side). This circle will touch the two longer sides but not reach the shorter sides unless the rectangle is a square.

Related Calculators

Additional Resources

Reference this content, page, or tool as:

"Rectangle Calculator" at https://MiniWebtool.com/rectangle-calculator/ from MiniWebtool, https://MiniWebtool.com/

by miniwebtool team. Updated: Jan 30, 2026

You can also try our AI Math Solver GPT to solve your math problems through natural language question and answer.

Related MiniWebtools:

Area of a Parallelogram Calculator
Area of a Trapezoid Calculator
Area of An Ellipse Calculator
Area of Equilateral Triangle Calculator
Square Calculator

Geometry Calculators:

Top & Updated:

Random PickerRandom Name PickerRelative Standard Deviation CalculatorLine CounterSort NumbersFPS ConverterRemove SpacesMAC Address GeneratorMAC Address LookupFeet and Inches to Cm ConverterWord to Phone Number ConverterBatting Average CalculatorRandom Quote GeneratorBitwise CalculatorPercent Off CalculatorFacebook User ID LookupLog Base 10 CalculatorSaturn Return CalculatorSum CalculatorNumber of Digits CalculatorSHA256 Hash GeneratorRandom Truth or Dare GeneratorERA CalculatorRoman Numerals ConverterDecimal to BCD ConverterAI ParaphraserCm to Feet and Inches ConverterSun, Moon & Rising Sign Calculator 🌞🌙✨Binary to Gray Code ConverterVideo to Image ExtractorOctal CalculatorMP3 LooperSquare Root (√) CalculatorAI Punctuation AdderPhone Number ExtractorNumber to Word ConverterFirst n Digits of PiBCD to Decimal ConverterOutlier CalculatorStandard Error CalculatorSalary Conversion CalculatorDay of Year CalendarRandom Credit Card GeneratorGray Code to Binary ConverterQuotient and Remainder CalculatorText FormatterCompound Growth CalculatorTime Duration CalculatorRemove Audio from VideoCompare Two StringsOn Base Percentage CalculatorMerge VideosSlugging Percentage CalculatorRandom Birthday GeneratorConvolution CalculatorAverage Deviation CalculatorCM to Inches ConverterBinary to BCD ConverterModulo CalculatorAudio SplitterIP Address to Hex ConverterRemove AccentScientific Notation to Decimal ConverterPercent Growth Rate CalculatorAntilog CalculatorMaster Number CalculatorLeap Years ListEmail ExtractorBonus CalculatorRandom Group GeneratorRemove Lines Containing...Random Fake Address GeneratorRandom Meal GeneratorImage SplitterList of Prime NumbersFirst n Digits of eMedian CalculatorRandom Superpower GeneratorDay of the Year Calculator - What Day of the Year Is It Today?Log Base 2 CalculatorSHA512 Hash GeneratorSample Standard Deviation CalculatorReverse VideoLove Compatibility CalculatorRemove Leading Trailing SpacesMAC Address AnalyzerRandom Emoji GeneratorNatural Log CalculatorURL ExtractorInvisible Text GeneratorRandom IMEI GeneratorHex to BCD ConverterRandom Object GeneratorName Number CalculatorVideo CompressorExponential Decay CalculatorSquare Numbers ListPER CalculatorVideo CropperMorse Code GeneratorAdd Prefix and Suffix to TextOPS CalculatorWHIP CalculatorSort Lines AlphabeticallyBCD to Binary ConverterLottery Number GeneratorBCD to Hex ConverterList RandomizerBreak Line by CharactersAverage CalculatorPVIFA CalculatorWAR CalculatorHypotenuse CalculatorActual Cash Value CalculatorNumber ExtractorAngel Number CalculatorRoot Mean Square CalculatorSum of Positive Integers CalculatorSHA3-256 Hash GeneratorAI Sentence Expander📅 Date CalculatorLbs to Kg ConverterHex to Decimal ConverterRandom String GeneratorAmortization CalculatorMarkup CalculatorPVIF CalculatorDecimal to Hex ConverterList of Fibonacci NumbersRandom Number PickerBlood Donation Time CalculatorField Goal Percentage CalculatorRandom Line PickerRatio to Percentage CalculatorAPY to APR CalculatorSort Text By LengthOne Rep Max (1RM) CalculatorName RandomizerRandom Animal GeneratorFixed Deposit CalculatorPPM to Percent ConverterCube Numbers ListCaesar Cipher ToolPercent to PPM ConverterSRT to TXT Converterkg to lbs ConverterXML ValidatorArithmetic Mean CalculatorBoard Foot CalculatorSquareness Checker (3-4-5 Rule) 📐Miter Angle CalculatorSlope and Grade CalculatorSine CalculatorCosine CalculatorTangent CalculatorArcsin CalculatorArccos (Inverse Cosine) CalculatorArctan CalculatorArctan2 CalculatorCosecant/Secant/Cotangent CalculatorHyperbolic Functions CalculatorRight Triangle CalculatorGeneral Triangle SolverLaw of Sines CalculatorLaw of Cosines CalculatorDMS to Decimal Degrees ConverterDecimal Degrees to DMS ConverterPolar to Cartesian ConverterCartesian to Polar Coordinates ConverterInteractive Unit Circle VisualizerTrigonometric Identities CalculatorTrigonometric Function GrapherAlgebraic Expression SimplifierRadical SimplifierRational Expression CalculatorPolynomial Factoring CalculatorExpand Polynomials CalculatorPolynomial Long Division CalculatorSynthetic Division CalculatorLinear Equation SolverAbsolute Value Equation SolverRadical Equation SolverSystem of Linear Equations SolverInequality SolverAbsolute Value Inequality SolverSystem of Inequalities GrapherFunction GrapherDomain and Range CalculatorInverse Function CalculatorFunction Composition CalculatorVertex and Axis of Symmetry CalculatorX and Y Intercept CalculatorHTML Entity Encoder/DecoderURL Slug GeneratorJSON String Escape/UnescapeMarkdown Table GeneratorSmart Quotes RemoverDaily Time Savings CalculatorLorem Ipsum GeneratorReadability Score CalculatorKeyword Density CheckerBionic Reading ConverterText to Speech ReaderFancy Text GeneratorZalgo Text GeneratorUpside Down Text GeneratorASCII Art GeneratorList Difference CalculatorText Column ExtractorText to SQL List ConverterInvisible Character RemoverStock Average CalculatorPosition Size CalculatorMargin Call CalculatorShort Selling Profit CalculatorRisk of Ruin CalculatorBlack-Scholes Option Pricing CalculatorOption Greeks CalculatorImplied Volatility CalculatorOptions Profit CalculatorImpermanent Loss CalculatorCrypto Arbitrage CalculatorSatoshi to USD ConverterCrypto Leverage CalculatorPivot Point CalculatorFibonacci Extension CalculatorStop Loss & Take Profit CalculatorKelly Criterion CalculatorMartingale Strategy CalculatorCompound Daily Interest CalculatorPip Value CalculatorGaussian Distribution GeneratorRandom Tournament Bracket GeneratorRandom Color Palette GeneratorRandom Country GeneratorRandom JSON GeneratorRandom User-Agent GeneratorRandom Coordinate GeneratorRandom Date GeneratorRandom Time GeneratorRandom IP Address GeneratorRandom Playing Card GeneratorMagic 8-BallRock Paper Scissors GeneratorCoin FlipperDice RollerSpin the WheelAquarium Volume & Stocking CalculatorAquarium Substrate CalculatorScale Model Conversion CalculatorPlant Spacing CalculatorDice Roll Probability CalculatorDepth of Field (DoF) CalculatorGolden Hour / Blue Hour CalculatorPrint Size & Resolution Calculator (DPI/PPI)Soap Making Lye Calculator (SAP)Candle Wax & Fragrance Oil CalculatorHomebrew ABV Calculator (Alcohol by Volume)Coffee Brew Ratio CalculatorBrine and Salinity CalculatorYarn CalculatorFabric CalculatorCross-Stitch Size CalculatorBaker's Percentage CalculatorDough Hydration CalculatorBaking Pan Size ConverterYeast Conversion CalculatorJSON to YAML ConverterJWT DecodercURL to JSON ConverterSQL FormatterCrontab Expression GeneratorFavicon GeneratorSVG OptimizerHtaccess Redirect GeneratorResistor Color Code CalculatorOhm's Law CalculatorVoltage Drop CalculatorPCB Trace Width CalculatorBattery Life CalculatorRandom PIN GeneratorRandom NanoID GeneratorRandom Port Number GeneratorRandom User Persona GeneratorRandom Writing Prompt GeneratorRandom Haiku GeneratorRandom Domain Name GeneratorRandom Movie PickerRandom Cocktail Recipe GeneratorRandom Activity GeneratorRandom Excuse GeneratorRandom US State GeneratorLemonade Stand CalculatorPizza Value CalculatorVampire Apocalypse CalculatorChristmas Tree CalculatorParking Ratio CalculatorGooglebot Crawl Size CheckerZombie Survival Time CalculatorHelium Balloon Lift CalculatorKinetic Energy Chicken CookerTeleportation Error Rate CalculatorHamster Power CalculatorBanana Radiation CalculatorFalling Through Earth CalculatorPenny Drop Impact CalculatorPopcorn Fill Room CalculatorLego Brick House CalculatorWedding Alcohol CalculatorPizza Party PlannerCaffeine Overdose CalculatorBBQ CalculatorTaco Bar CalculatorBeer Chill Time CalculatorSpaghetti Portion CalculatorCocktail ABV CalculatorChocolate Fountain CalculatorCheese Board Calculator