Quirkulator

Web Development Calculators

15 calculators covering CSS units, viewport maths and aspect ratios, each with its formula and worked examples.

Web Development Calculators brings together 15 calculators for CSS units, viewport maths and aspect ratios, including Aspect Ratio Resize Calculator, Golden Ratio Typography Calculator, Line Height Calculator and PX to PT Calculator.

Every page states its method up front — which formula, which convention, which assumptions — because those choices change the answer, and a calculator that hides them is only pretending to be precise.

All 15 pages compute in your browser: nothing you type is sent anywhere, and results update as you edit. Each one carries worked examples, interpretation bands where a score needs context, and a FAQ answering what people actually ask about that calculation.

The collection is part of Text & Web Tools, and every page links to the neighbouring calculations you usually need next.

15 pages in this collection

Aspect Ratio Resize CalculatorResize width or height while keeping the original proportions.Contrast Ratio CalculatorCheck text contrast against the WCAG thresholds for AA and AAA.CSS Grid Column Width CalculatorWork out exact column widths once gaps and padding are removed.Golden Ratio Typography CalculatorDerive line height and measure from the golden ratio.Image Scale CalculatorScale an image by a percentage and see the pixel and data cost.Letter Spacing CalculatorConvert tracking in thousandths of an em into usable CSS values.Line Height CalculatorFind a line height that suits your font size and measure.Modular Type Scale CalculatorGenerate a type scale from a base size and a musical ratio.PX to EM CalculatorConvert pixels to em against the parent font size, including nesting.PX to Percent CalculatorConvert a pixel width into a percentage of its container.PX to PT CalculatorConvert screen pixels to typographic points for print stylesheets.PX to REM CalculatorConvert pixel values to rem against your root font size.PX to VW CalculatorConvert a pixel value into viewport width units at a reference width.REM to PX CalculatorConvert rem values back to the pixels they will actually render at.Viewport Breakpoint CalculatorConvert breakpoints between pixels and em, and check the gaps between them.

Related collections

Text & Web Tools →
CSS Unit Converters34 conversion pages for CSS length units, each with its exact factor, the formula and a reference table.34 calculatorsText & Readability Tools18 calculators covering counting words and scoring readability, each with its formula and worked examples.18 calculatorsTransfer & Bandwidth Calculators15 calculators covering download time, transfer time and bandwidth needs, each with its formula and worked examples.15 calculatorsColour Calculators10 calculators covering hex, RGB, HSL and contrast ratios, each with its formula and worked examples.10 calculators