COSTUI
Design better interfaces — UI/UX guides, design-system references, and the free calculators every front-end builder needs.
From checking color contrast and converting px to rem to building type and spacing scales, generating color ramps, and working out aspect ratios, CostUI pairs free hands-on design calculators with practical guides and a browsable museum. Design clearer, build faster.
UI/UX Design Tools & Calculators
Free tools for interface work — color contrast checker, px to rem converter, type scale generator, color shades generator, spacing scale generator, and aspect ratio calculator.
Color Contrast Checker
Check the WCAG 2.1 contrast ratio between a text and background color, with pass/fail for AA and AAA at normal and large text sizes.
PX to REM Converter
Convert pixels to rem or rem to pixels for any root font size, with a reference table of the sizes you reach for most.
Type Scale Generator
Build a modular type scale from a base size and a ratio — minor third, major third, perfect fourth, golden — in px and rem.
Color Shades Generator
Turn one base hex into a full ramp of tints and shades from 10% to 90%, ready to paste into your palette or design tokens.
Spacing Scale Generator
Generate a consistent spacing scale from a base unit — linear or geometric — with every step in px and rem.
Aspect Ratio Calculator
Solve a missing width or height for any ratio, or reduce a pixel size to its simplest ratio.
The Museum
A browsable museum sits alongside the calculators and guides — a set of illustrated collections you can explore when you want a break from the numbers, with every entry drawn from Wikipedia and Wikimedia Commons.
Tour the museum →From the Journal
Guides on color and accessibility, typography and type scales, spacing and layout, design systems, and front-end CSS — practical reading to pair with the calculators above.
Inexpensive Ui/Ux Templates: Professional Insights and Tips
The Ultimate Resource for Affordable UI/UX Design Solutions In today’s fast-paced digital landscape, creating an exceptional user experience is crucial for any project’s success. However, many designers and developers face budget constraints that make high-end design solutions unattainable. This guide explores the world of inexpensive UI/UX templates that provide quality design without emptying your wallet. […]
Ui Elements For Developers: Practical Applications and Benefits
The Ultimate Toolbox for Modern UI Development: Essential Components Every Developer Should Master In today’s fast-paced digital landscape, creating intuitive user interfaces is no longer optional—it’s essential. Whether you’re building web applications, mobile platforms, or desktop software, mastering UI elements can make or break your product’s success. This guide dives deep into the core components […]
Why Budget-Friendly Graphic Templates Are Revolutionizing Visual Content Creation
The Ultimate Resource for Affordable Graphic Design Templates That Deliver Professional Results Without Breaking the Bank In today’s visually driven digital landscape, high-quality graphics are essential across industries—from marketing campaigns and website design to social media branding and print materials. Yet many small businesses, freelancers, and creative professionals face a common challenge: creating professional-grade visuals […]
The Affordable Artistry of Web Design: Mastering Low-Cost Website Themes Without Compromise
The Affordable Artistry of Web Design: Mastering Low-Cost Website Themes Without Compromise In today’s digital marketplace, establishing an online presence is not merely optional—it’s essential. Yet many entrepreneurs, small business owners, and creative professionals find themselves at a crossroads when choosing between premium design solutions and budget-friendly alternatives. This guide explores how low-cost website themes […]
Ui Kits For Designers: Practical Applications and Benefits
The Ultimate Resource Hub for UI Kit Mastery: Enhancing Productivity Through Pre-Built Components In today’s fast-paced design landscape, time is currency, and efficiency is paramount. For designers navigating complex projects, leveraging pre-built UI kits has become an essential strategy to streamline workflows and maintain consistency across platforms. These kits offer ready-to-use components that not only […]
Ui/Ux Prototyping Tools: Professional Insights and Tips
The Ultimate Toolkit for Crafting Exceptional Digital Experiences: A Deep Dive Into UI/UX Prototyping Software In today’s fast-paced digital landscape, creating seamless user experiences is no longer optional—it’s essential. From mobile apps to complex web platforms, every interaction demands precision, creativity, and an unwavering commitment to usability. To achieve these goals, designers rely heavily on […]
Keep Learning
Plain-language explainers on how contrast ratios, rem units, modular type scales, spacing systems, and aspect ratios actually work — everything you need to design and build interfaces with more confidence.
Visit the Learn hub →