calculatory.app

Design Tools

6 free tools for designers. Built by a designer, for the small conversions that interrupt real work — all running in your browser.

Color Contrast Checker

Check text and background colors against WCAG AA and AAA, including large text and UI components, and get the nearest passing shade.

Hex to RGB Converter

Convert hex color codes to RGB, HSL, and HSB values. Includes color preview and CSS output.

PX to REM Converter

Convert pixels to rem and back at any root font size, with points, percent, a reference table and copy-ready CSS.

Aspect Ratio Calculator

Find the ratio of any dimensions, resize images and video without distortion, and copy the CSS aspect-ratio value.

Tints & Shades Generator

Turn one color into an 11-step 50–950 scale with WCAG contrast on every step. Export to CSS variables, Tailwind v4, Tailwind v3 or JSON.

DPI Calculator

Convert pixels to print size at any DPI, find the pixels a print needs with bleed, and check whether an image is sharp enough to print.

About these tools

This category collects the color, type and layout maths that designers look up dozens of times a week — the moments between a design file, a style guide and a line of CSS where you need an exact value, not an approximation.

The Color Contrast Checker tests any pair of colors against WCAG AA and AAA without rounding near misses into passes, and suggests the nearest shade of your color that passes. The Hex to RGB Converter turns hex codes into RGB, HSL and HSB with a live preview. The PX to REM Converter works at any root font size, and the Aspect Ratio Calculator resizes images and video proportionally and shows when a resolution is only close to a named ratio.

The Tints & Shades Generator turns a single brand color into a full 50–950 scale, with contrast on every step, ready to paste into CSS or Tailwind. The DPI Calculator covers the print side: how large a file prints, how many pixels a print needs including bleed, and whether an image will hold up at the size you want.

Every tool runs entirely in your browser: nothing is uploaded, nothing is stored, and no account is needed. Calculatory is built by Gaurav Yadav, a designer with 26 years of practice.