REM to PX Converter - Free Online REM to Pixel Calculator
Need to convert rem to px for pixel-perfect designs? You’re in the right place.
Here’s the deal:
Our free rem to px converter gives you instant, accurate pixel values from rem units. Perfect for design handoffs and debugging.
How to Use This REM to PX Converter
Using this tool is straightforward:
- Enter a value - Type your rem or pixel value in either input field
- Select your base font size - Choose from 6px to 32px using the dropdown menu (default is 16px)
- Get instant results - The conversion happens automatically as you type
Want to know the best part?
This is a bidirectional converter. You can convert rem to px OR px to rem - just enter your value in either field and the other updates instantly. Need the reverse? Try our PX to REM converter .
Pro tip: Always verify the base font size matches your project’s root font-size. Different projects may use 10px, 14px, or 18px bases.
Why Convert REM Back to PX?
You might be wondering:
If rem is so great for responsive design, why would anyone need to convert back to pixels?
Here’s the thing:
Pixels are still essential in many real-world scenarios:
- Design handoffs - Designers work in pixels (Figma, Sketch, Adobe XD)
- Debugging layouts - Browser DevTools show computed values in px
- Pixel-perfect requirements - Some elements need exact pixel dimensions
- Legacy code maintenance - Older codebases may use px values
- Client communication - Stakeholders understand pixels better than rem
What Is REM?
REM stands for “Root EM” - a relative CSS unit based on the root element’s font size.
Now:
If your <html> element has font-size: 16px, then:
- 1rem = 16px
- 2rem = 32px
- 0.5rem = 8px
REM values scale proportionally when the root font size changes, making layouts responsive to user preferences.
What Is PX (Pixel)?
PX stands for pixels - the most fundamental unit in digital design.
Here’s what makes pixels valuable:
- Absolute precision - 1px is always 1px, no calculations needed
- Universal understanding - Everyone from designers to clients understands pixels
- Design tool standard - All major design tools export in pixels
- Browser DevTools - Computed styles are displayed in pixels
- Print consistency - Pixels map predictably to physical dimensions
The bottom line:
Pixels provide the certainty and precision that relative units can’t offer.
REM vs PX: When Pixels Win
Here’s a comparison showing when px is the better choice:
| Scenario | Use REM | Use PX |
|---|---|---|
| Body text size | ✅ Best | ❌ Not ideal |
| Borders | ❌ May blur | ✅ Crisp lines |
| Box shadows | ❌ Over-scales | ✅ Controlled |
| Media query breakpoints | ❌ Unpredictable | ✅ Consistent |
| Design specs | ❌ Needs conversion | ✅ Direct match |
| 1px dividers | ❌ May disappear | ✅ Always visible |
| Icon sizing | Depends | ✅ Often better |
It gets better:
Using px strategically alongside rem gives you the best of both worlds:
- Predictable borders - 1px borders stay crisp at any zoom
- Consistent breakpoints - Media queries behave reliably
- Design accuracy - Match mockups pixel-for-pixel
- Debugging clarity - See exact computed values
How REM to PX Conversion Works
The rem to px formula is simple:
px = rem × base-font-sizeFor example, with a 16px base font:
- 1rem × 16 = 16px
- 1.5rem × 16 = 24px
- 2rem × 16 = 32px
- 0.5rem × 16 = 8px
To convert px to rem:
rem = px ÷ base-font-sizeThis is crazy:
If your project uses a 10px base (62.5%), the math becomes even easier: 1.6rem = 16px, 2rem = 20px.
Common REM to PX Conversion Table
Here are frequently used rem to px conversions (base 16px):
| REM | Pixels | Common Use Case |
|---|---|---|
| 0.25rem | 4px | Hairline borders, micro spacing |
| 0.5rem | 8px | Small gaps, icon padding |
| 0.75rem | 12px | Small text, captions |
| 0.875rem | 14px | Secondary text, labels |
| 1rem | 16px | Default body text |
| 1.125rem | 18px | Large body text |
| 1.25rem | 20px | H4 headings |
| 1.5rem | 24px | H3 headings, section spacing |
| 2rem | 32px | H2 headings |
| 3rem | 48px | H1 headings |
| 4rem | 64px | Hero text, display headings |
Bulk Conversion
Need to convert a whole stylesheet or a long text block? Use the Bulk Conversion panel.
- Paste CSS/text that contains rem values (e.g.
1.25rem). - Choose the base font size used in your project.
- Copy the output with all rem values converted to px.
Bulk conversion replaces rem values only (rem -> px) and uses the base font size you select.
Frequently Asked Questions
When should I use px instead of rem?
Use pixels for:
- Borders - 1px borders should stay crisp at any size
- Box shadows - Fixed shadows look more consistent
- Media queries - Define breakpoints in px for reliability
- Hairline dividers - Thin lines that shouldn’t scale
- Design spec matching - When you need exact pixel values
How do I find the base font size of a website?
Open your browser DevTools (F12), select the <html> element, and check the computed font-size value. Most sites use 16px, but some use 10px (62.5%), 14px, or 18px.
Why do designers work in pixels, not rem?
Design tools like Figma, Sketch, and Adobe XD are pixel-based. Designers need exact measurements for layouts, spacing, and typography. The rem to px conversion happens during development, not design.
Can I use both px and rem in the same project?
Absolutely. Best practice:
- rem for font sizes, padding, margins (scalable elements)
- px for borders, shadows, breakpoints (fixed elements)
This hybrid approach gives you accessibility benefits of rem while maintaining pixel precision where needed.
How do browser DevTools show rem values?
DevTools show computed values in pixels. If you set font-size: 1.5rem and your base is 16px, DevTools will display font-size: 24px. This is why rem to px conversion is essential for debugging.
What if my base font size changes responsively?
If you use clamp() or media queries to change the root font size, your rem values will produce different pixel results at different viewport sizes. Use this converter with each base size to verify your design at all breakpoints.
Is there a performance difference between px and rem?
No measurable performance difference. Browsers calculate rem to px instantly. Choose based on use case, not performance.
Why does 0.5rem sometimes look wrong?
With a 16px base, 0.5rem = 8px. But on some displays, sub-pixel rendering can make certain values look blurry. For thin borders or dividers, stick with whole pixel values like 1px.