Solve any rectangle measurement quickly — find Area and Perimeter together, isolate a missing Length or Width, compute the Diagonal, or verify angles — using dedicated calculators built to handle whichever dimensions you already have.
Browse the Most Popular list to see which tools others use most, or try the Trending tab for recently active additions. Every calculator is free, sign-up-free, and runs on any phone, tablet, or desktop.
- Volume Calculator
- Area Calculator
- Perimeter Calculator
- Surface Area Calculator
- Circle Calculator
- Rectangle Calculator
- Triangle Calculator
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TV Screen Size CalculatorCalculate a TV or monitor's actual width, height and screen area from its diagonal size and aspect ratio (e.g. 16:9). Free, instant, accurate.
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Rectangular Prism Volume CalculatorCalculate the volume of a rectangular prism (cuboid) instantly with length × width × height. Also shows surface area. Free and easy to use.
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Cubic Feet of a Rectangle (Box) CalculatorCalculate the cubic feet (volume) of a rectangular box from its length, width and height in feet. Get instant ft³, yd³ and in³ results.
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Square Meters of a Rectangle CalculatorCalculate the area of a rectangle in square meters instantly. Enter length and width in meters to find m² area plus the perimeter.
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Rectangle Aspect Ratio CalculatorFind the aspect ratio of any rectangle from its width and height. Reduces to the simplest integer ratio (e.g. 1920×1080 = 16:9) plus a decimal ratio.
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Perimeter of a Rectangle CalculatorCalculate the perimeter of a rectangle instantly using P = 2(l + w). Enter length and width to get perimeter, area, and diagonal.
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Number of Tiles to Cover a Rectangle CalculatorCalculate how many rectangular tiles you need to cover a rectangular floor or wall, including a waste allowance for cuts and breakage.
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Rectangle Fence Cost CalculatorEstimate the cost to fence a rectangular yard. Enter length, width, and price per foot to get the perimeter and total fencing material cost instantly.
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Rectangle Area in Acres CalculatorCalculate the area of a rectangular plot in acres from its length and width in feet. Instant feet-to-acres conversion using 1 acre = 43,560 sq ft.
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Rectangle Square Footage Cost CalculatorCalculate the total cost of a rectangular area by multiplying its square footage (length × width) by your price per square foot. Fast and free.
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Rectangle Gravel/Mulch Volume CalculatorCalculate how many cubic yards of gravel, mulch, sand or topsoil you need to fill a rectangular area at a given depth. Enter length, width and depth.
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Rectangular Concrete Slab Volume CalculatorCalculate how many cubic yards of concrete you need for a rectangular slab from its length, width, and thickness. Fast, accurate, and free.
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Paint Needed for a Rectangular Wall CalculatorCalculate how many gallons of paint you need for a rectangular wall from its length, height, coverage per gallon, and number of coats.
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Rectangular Lumber Board Feet CalculatorCalculate board feet of rectangular lumber from length, width and thickness in inches. Multiply by board count for total BF instantly.
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Rectangular Pool Volume CalculatorCalculate how many gallons of water your rectangular pool holds. Enter length, width, and average depth in feet to get the volume instantly.
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Square Yards of a Rectangle CalculatorConvert a rectangle's length and width in feet to square yards instantly. Enter dimensions to get area in square yards and square feet.
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Rectangle Area Moment of Inertia CalculatorCalculate the area moment of inertia (Ix and Iy) of a rectangular cross-section about its centroidal axes from width and height.
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Rectangular Room Square Footage CalculatorCalculate the square footage of a rectangular room instantly. Enter length and width in feet to get area in sq ft, sq yards, and sq meters.
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Missing Side of a Rectangle from Perimeter CalculatorFind the unknown side of a rectangle from its perimeter and one known side. Uses missing_side = P/2 − known_side. Instant, free, and accurate.
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Rectangular Carpet Cost CalculatorEstimate the cost of carpeting a rectangular room. Enter length, width and price per square metre to get total floor area and carpet cost instantly.
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Missing Side of a Rectangle from Area CalculatorFind the missing side of a rectangle from its area and one known side. Enter area and a side to get the other side plus the perimeter instantly.
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Maximum Area Rectangle for a Fixed PerimeterFind the maximum area of a rectangle for a given fixed perimeter. The optimum is always a square with side P/4 and area (P/4)². Free online tool.
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Rectangular Wall Area CalculatorCalculate the area of a rectangular wall from its length and height, then subtract doors and windows to get the net paintable or tileable area in m².
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Laminate/Flooring Boxes for a Rectangular Room CalculatorCalculate how many boxes of laminate or flooring you need for a rectangular room, including a waste allowance for cuts and mistakes.
Frequently asked questions
Which rectangle properties can I calculate?
You can solve for area, perimeter, length, width, diagonal, and angles — starting from whichever measurements you already know. Tools like the Rectangle Diagonal Calculator and Rectangle Angle Calculator handle the less obvious outputs that come up in carpentry, construction, and classroom geometry.
How accurate are the results?
Calculators use standard geometric formulas — A = l × w, d = √(l² + w²), and related expressions — with double-precision arithmetic. For safety- or construction-critical work, verify results against the governing standard and have a qualified engineer review the figures before proceeding.
Is there any cost?
No — all rectangle calculators in this collection are completely free. There is no subscription, no account required, and no features hidden behind a paywall — every result is instantly accessible to everyone.
Are the numbers I enter stored anywhere?
No. Every calculation runs locally in your browser. We do not collect, log, or transmit any values you input — your measurements stay on your device.
Which rectangle calculator is used most?
The Most Popular list is ranked by actual usage. The Rectangle Area and Perimeter Calculator typically leads, but check the Trending tab for tools that are gaining traction with other users right now.
