CSS Unit Converter

The CSS Unit Converter generates a ready-to-use Bootstrap 5 conversion reference card that displays calculated values across px, rem, em, vw, and percentage units based on your project's base font size and viewport width. It is built for frontend developers and designers who need accurate unit conversions without leaving their workflow. Paste the output directly into any Canvas HTML or Bootstrap 5 project.

Configuration

Content

Card Title

Card Subtitle

Pixel Value to Convert (px)

Base Font Size (px)

Viewport Width (px)

Container Width (px) for % calc

Footer Notes

Design

Accent Color

Header Text Color

Card Border Radius (px)

Table Style

Card Shadow

Layout

Card Width

Show Unit Badge Labels

How to Use

1. Configure your base font size, viewport width, and the pixel value you want to convert. 2. Adjust the card title, accent color, border radius, and which unit rows to display. 3. Preview the generated conversion reference card in real time. 4. Copy or download the HTML and drop it straight into your project.

Why Use This Tool?

Manual CSS unit conversion is error-prone and interrupts your flow, especially when switching between design tools and code. This tool generates a polished, shareable reference card you can embed in a style guide, documentation site, or dev dashboard in seconds. No JavaScript libraries, no npm packages, no build step required.

Frequently Asked Questions

What is the CSS Unit Converter?

The CSS Unit Converter is a free tool that takes a pixel value and your project's base configuration, then generates a Bootstrap 5 HTML card showing equivalent values in rem, em, vw, and percentage units for instant reference.

How does rem conversion work and why does the base font size matter?

rem (root em) is always relative to the root element's font size, which browsers default to 16px. If you change the root font size in your CSS (for example, html { font-size: 18px; }), every rem value changes proportionally. This tool lets you set your actual base font size so the converted rem values match your real project output, not just the browser default. For example, 32px at a base of 16px equals 2rem, but at a base of 18px it equals approximately 1.778rem.

Is it free?

Yes — the CSS Unit Converter is completely free with no signup required. Built by the CanvasBuilder.co team.