# PX to REM Converter > Free px to rem converter - instant CSS unit math at any base font size. 16px = 1rem, 24px = 1.5rem, 8px = 0.5rem. Copy with one click, no signup. - **Source:** DevDreaming (https://devdreaming.com) - **Canonical URL:** https://devdreaming.com/tools/px-to-rem-converter - **Category:** Frontend & CSS - **Price:** Free - no signup --- ## What this tool does The PX to REM Converter is a free tool that turns CSS pixel values into rem units based on a root font size you choose. Enter a pixel value, set your base size (16px by default), and it shows the rem result instantly. It also shows an em result assuming the relevant font size equals that base. REM units are calculated relative to the root html font size, which makes layouts scale predictably when a user changes their browser font setting. The converter does the division for you and also lists a reference table of common sizes so you can grab a value without typing. It runs entirely in your browser with no signup and no data leaving your machine. Conversions update live as you type. ## How to use it 1. Set the Root Font Size field to your project base, which is 16px in most browsers and frameworks. 2. Enter the pixel value you want to convert in the Pixel Value field. 3. Read the Conversion Result card for the rem value and division used. The em figure assumes the relevant font size matches the chosen root size. 4. Use the preset buttons (Small, Regular, Large, Extra Large) to load common values quickly. 5. Click any size in the Common Conversions table to load it into the converter. 6. Click the copy icon to copy the rem or em value, or press Ctrl+L to reset the fields. **[Open the PX to REM Converter tool ->](https://devdreaming.com/tools/px-to-rem-converter)** This tool runs in your browser and cannot be operated from this Markdown copy - open the link above to use it. ## What you can use it for - Converting a design handoff measured in pixels into rem units for an accessible, scalable stylesheet. - Migrating an existing pixel-based CSS file to rem so it respects user font size preferences. - Checking the rem equivalent of a spacing or font-size value while writing a component. - Working with a non-standard root font size, such as the 62.5% trick that makes 1rem equal 10px. - Teaching or learning how the px-to-rem formula works using the shown division. - Looking up common conversions like 24px to rem without doing mental math. ## Key features - Live conversion that updates as you type, with results shown to four decimal places. - Adjustable root font size so you can convert against any base, not just 16px. - A reference table of common pixel sizes with clickable values. - One-click copy of the rem result or the em figure calculated at the same base size. ## Frequently asked questions ### How do you convert px to rem? Divide the pixel value by the root font size. With the standard 16px root, 24px divided by 16 equals 1.5rem and 8px equals 0.5rem. This converter applies that formula automatically and lets you change the root size if your project uses a different base. ### What is 16px in rem? 16px equals 1rem when the root font size is 16px, which is the default in most browsers. If you change the root size, the result changes accordingly, since rem is always relative to the root. ### What is the difference between rem and em? A rem is relative to the root html element's font size. An em depends on context: for font-size it uses the parent's font size, and for many other properties it uses the element's own font size. The em figure here assumes that relevant size equals the root size you entered. ### Why should I use rem instead of px in CSS? Rem units scale with the user's chosen browser font size, so a person who increases their default text size gets a proportionally larger layout. Fixed pixels ignore that preference, which is worse for accessibility. ### Is this px to rem converter free to use? Yes. The converter is completely free, requires no signup, and runs entirely in your browser. No values you enter are sent to a server. ### Can I convert rem back to px with this tool? This tool converts pixel input into rem and em output. To go the other way, multiply the rem value by your root font size: at a 16px root, 1.5rem times 16 equals 24px. ## Privacy All tools on DevDreaming run entirely in your browser - your input is never uploaded to a server. --- ## Related on DevDreaming - [All Free Developer Tools](https://devdreaming.com/tools) - [Frontend & CSS Tools](https://devdreaming.com/tools/category/frontend-css) - [Clamp() Calculator](https://devdreaming.com/tools/clamp-font-size-calculator) - [Aspect Ratio Calculator](https://devdreaming.com/tools/aspect-ratio-calculator) - [Cursor CSS Previewer](https://devdreaming.com/tools/cursor-property-viewer) - [CSS Triangle Generator](https://devdreaming.com/tools/triangle-generator) - [Box Model Visualizer](https://devdreaming.com/tools/css-box-model-visualizer) - [CSS Variables Generator](https://devdreaming.com/tools/css-variables-generator) --- _This is the Markdown twin of a page on **DevDreaming** - free developer tutorials, tools, and AI resources. 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