design & development tools - REM to pixel

REM to PX Converter Online
with Conversion Table

Your Go-to Tool for Converting REM to Pixels (REM to PX) – Free and Easy!

REM ↔ PX Converter

Convert rem to pixels and pixels to rem using your base font size. Perfect for responsive, accessible typography.

REM to Pixels

Example: 0.75, 1, 1.25, 1.5
Pixels
—
Copied!

Formula: px = rem × base font size

Pixels to REM

Example: 12, 16, 20, 24
REM
—
Copied!

Formula: rem = px ÷ base font size

Set your own root font size if it’s different from 16px.
Quick presets:

Quick rem → px reference (16px base)

REM Pixels (px)
0.75 rem12 px
1.00 rem16 px
1.25 rem20 px
1.50 rem24 px
2.00 rem32 px

Tip: using rem instead of px makes your typography more scalable and accessible. For most projects, a 16px base works well.

Common REM to PX sizes at 16px…

  • 0.25 rem to px is 4 px

  • 0.5 rem to px is 8 px

  • 0.75 rem to px is 12 px

  • 1 rem to px is 16 px

  • 1.5 rem to px is 24 px

  • 2 rem to px is 32 px

  • 3 rem to px is 48 px

  • 4 rem to px is 64 px

Common REM to Pixel sizes at 96 PPI…

  • 1.5 rem to px is 24 px

  • 1.6 rem into pixels is 25.6 px

  • 1.7 rem to px is 27.2 px

  • 1.8 rem to pixels is 28.8 px

  • 1.9 rem into px is 30.4 px

  • 2 rem to pixels is 32 px

  • 2.2 rem to px is 35.2 px

  • 2.4 rem into pixels is 38.4 px

Common REM PX sizes at 96 PPI…

  • 2.5 rem to px is 40 px

  • 2.6 rem into pixels is 41.6 px

  • 2.8 rem to px is 44.8 px

  • 3 rem to pixels is 48 px

  • 3.2 rem into px is 51.2 px

  • 3.5 rem to px is 56 px

  • 4 rem into pixels is 64 px

  • 4.5 rem to px is 72 px

Common REM to PX sizes at 96 PPI…

  • 5 rem to pixels is 80 px

  • 6 rem into px is 96 px

  • 6.5 rem to px is 104 px

  • 7 rem to pixels is 112 px

  • 7.5 rem into px is 120 px

  • 8 rem to pixels is 128 px

  • 8.5 rem into px is 136 px

  • 10 rem to px is 160 px

The Ultimate Guide to Converting REM to PX...

In modern web design and frontend development, the interplay between relative and absolute measurement units is constant.

One minute you’re working with fluid layouts and scaling typography using the rem unit; the next you’re handed a design spec or need to liaise with a client or developer who thinks in pixels (px). How do you bridge the two worlds effortlessly?

As the founder of our design & development agency, I’ve seen this challenge play out across dozens of projects. Designers deliver in rem-based systems for scalability and accessibility, developers need pixel values for precise layout, clients expect visual consistency across devices.

 That’s why we built this REM to PX Converter — it gives you instant, accurate pixel equivalents of any rem value, grounded in the root font size your project uses.

Let’s walk through everything you need to know: what rem and px mean, why conversions matter, how to calculate them, how to use the tool, best practices, use-cases, FAQs and more — so you get both the theory and the workflow from an agency-owner’s practical point of view.

What are REM units and Pixels (px)?

REM (root em)

The rem unit stands for root em: it’s a relative CSS unit that uses the font size of the root element (typically the <html> element) as its basis. If you set html { font-size: 16px; }, then 1rem equals 16px. Change the root font size and the rem values scale accordingly. SitePoint+2finsweet.com+2

Because rem is relative, it enables scalable, accessible design: if a user increases their browser base font size, then all elements specified in rem scale appropriately, supporting better accessibility. BrowserStack+1

Pixel (px)

The px unit is an absolute unit referring to a dot on the screen (in CSS terms). For most browser work, px is fixed and predictable: 16px means a block that many device-pixels (or CSS pixels) wide. Because of this fixed nature, px is still widely used when exact layout size matters — margin, padding, images, fixed components.

When you convert from rem → px, you’re translating a relative scalable unit into a fixed absolute one — which is why the root font size becomes a key dependency.

Why Convert REM to Pixels?

In our agency workflows, we repeatedly hit scenarios where rem values are intuitive for design scale, but pixel values are needed for precision, handoffs, or dev specs. Some key real-world use cases:

  • Design handoff to dev: A designer uses 1.5rem for a heading (for scalability), but the dev asks “how many px is that for the breakpoint?” The conversion gets clarity.

  • Responsive typography & spacing system: You set core spacing values in rem for accessibility and responsiveness. But for a fixed-width component or image you might need the pixel equivalent to align elements.

  • Legacy design or fixed-pixel assets: If you’re integrating design into an older system built around px, you may need to convert the rem values into px so the two systems match.

  • Client communication: Clients often talk in “px” because that’s what they see in tools like Figma or on screen. Explaining “1.5rem = 24px (at root font size 16px)” helps bridge design talk with dev talk.

  • Print pre-visualisation or fixed layout previews: Even though rem is a web-unit, when previewing in pixels (screenshots, mockups), you often want pixel-accurate measurements for alignment.

In short, the conversion tool helps preserve scalability and accessibility (via rem) and precision and predictability (via px).

The Key Dependency: Root Font Size (and Browser Defaults)

This is the hinge of the conversion: what is your root font size?

By default, browsers set html { font-size: 16px; }. So in that standard environment:

However:

  • Some projects override the root font size (e.g., html { font-size: 10px; } for easier math)

  • Some frameworks use % or vw formula to base root size on viewport width

  • Some user settings (browser zoom, default font size) alter rendering

Thus when converting rem to px, you must know or decide the root font size your project uses. Without that, px values could be off.

Conversion Formula + Example Calculation

Here’s the formula our converter uses in the background:

Pixels (px) = rem × RootFontSize (in px)

Example 1: Default root = 16px

Let’s convert 2.5rem → px.

px = 2.5 × 16px = 40px

So 2.5rem = 40px when root font-size is 16px.

Example 2: Custom root = 10px (sometimes used for easier maths)

If html { font-size: 10px; } and you want 1.8rem:

px = 1.8 × 10px = 18px

Hence 1.8rem = 18px in that system.

Example 3: Reversing thought-flow

You see 48px, you ask “how many rem is that?”. If root is 16px:

rem = 48px ÷ 16px = 3rem

So 48px = 3rem.

By embedding this logic into our tool, you don’t need to manually compute—just plug and convert.

How to Use Our REM to PX Converter Tool

Here’s the process for your team or clients:

  1. Enter the REM Value: Type the value in rem you want converted (e.g., 3.25rem).

  2. Select or Input the Root Font-Size: Choose the project’s root value (16px is default; adjust if your html uses 10px, 18px, etc.).

  3. Get the Pixel Equivalent (px): The converter shows the result instantly (e.g., 3.25rem × 16px = 52px).

  4. Copy the Result: Use the copy button to paste the px value into your CSS, design specs, dev comments or client documentation.

This tool helps our design-dev workflows to stay aligned: designers use rem for scalability, devs use px for precision — both referencing the same underlying measurement.

Advantages + Use Cases (Founder Voice)

From my view as the founder of a digital agency, here’s what conversion tools like this bring to our workflows:

  • Speed: No mental math or spreadsheet toggling. Value entered → result output in seconds.

  • Accuracy: Eliminates small calculation mistakes (e.g., forgetting root font size or mis-typed values) which can cascade into misalignment, layout drift or inconsistent spacing.

  • Team Consistency: Every designer and developer uses the same conversion logic; when we hand off a design from Figma to dev, both parties speak the same “unit language”.

  • Client Clarity: Clients often don’t care about rem vs px—they care “how big will this be on screen?”. Showing “1.5rem = 24px” delivers next-level transparency.

  • Workflow Integration: We embed this into our style guide, design system, and hand-off checklist. As soon as someone uses rem units, they have the px value for precision tasks.

When you scale across projects, dozens of pages, multiple teams, a small tool like this removes friction and supports quality at scale.

Best Practices for Converting REM to PX

Here are refined pro tips to ensure you get optimal outcomes:

1. Define and Document Your Root Font-Size Early

In your CSS/Framework (or style guide) set: html { font-size: 16px; } (or whatever base you choose). Make sure every team member knows the baseline. If you change it (e.g., via media queries), conversions should reflect that. finsweet.com+1

2. Use REM for Scalable Properties — PX for Precision

Use rem units for properties that should scale (typography, spacing, margins). Use px when you need exact pixel fidelity (icons, borders, fixed-width assets). Then convert rem → px when handing over to dev for fixed-elements.

3. Round Thoughtfully

If you convert and get 52.3px, decide if you’ll round to 52px or 52.5px. Ensure rounding aligns with your visuals and consistency. Avoid crazy decimals like 3.746rem that complicate maintenance.

4. Update Root Font-Size with Care

If you ever change the root font size (e.g., for accessibility or responsive scaling), ensure your conversions and rem-based values recalc. For example, if root goes from 16px → 18px, then 1.5rem goes from 24px -> 27px.

5. Keep Related Tools Close

Often conversions go both ways: px → rem, rem → px, px → em, px → vw. In your hand-off process, have these tools inter-linked so your team can jump between units seamlessly.

FAQs

Here are some of the frequently asked questions about conversions…

Pixels = rem × root font-size (in px).

Yes. Simply use the actual root font size your project uses (e.g., 10px, 18px) and apply the formula accordingly.

Because rem units scale with the root font size and respect user preferences (accessibility). Pixel values remain fixed regardless of user settings.

When you need fixed layout elements, precise asset sizes, or pixel-perfect alignment and you don’t want scaling based on user settings or root font changes.

It can, if you rely solely on px values. The converter helps you understand the pixel equivalent, but if you then hardcode px where rem was meant for scalability, you may lose responsiveness. Use conversions thoughtfully.

Assuming root font size of 16px, 1rem = 16px. If root is different, adjust accordingly.

Related tools you might find helpful

If you work with CSS, responsive layouts, or UI design, these converters will help you switch between different units quickly.

Each tool solves a specific use case – whether you're adjusting font sizes, spacing, or converting print measurements to screen pixels. Explore the full set below to speed up your workflow…

Complete list of conversion tools

  • PX to CM Converter – Convert pixels into centimeters for print-friendly layouts and accurate sizing.

  • CM to PX Converter – Convert centimeters to pixels when designing for screens or digital assets.

  • PX to REM Converter – Convert pixels to rem for scalable and accessible typography.

  • REM to PX Converter – Convert rem values back to fixed pixel units for precise layout control.

  • PX to Inches Converter – Convert pixels into inches for print sizes or physical measurements.

  • Inches to PX Converter – Convert inches into pixel dimensions based on standard screen density.

  • MM to PX Converter – Convert millimeters to pixels for UI, print, and product mockups.

  • PX to MM Converter – Convert pixels to millimeters with accurate unit mapping.

  • MM to Inches Converter – Convert millimeters into inch values for sizing and print design.

  • Inches to MM Converter – Convert inches into millimeters for exact physical measurements.

  • VW to PX Converter – Convert viewport-width units into pixel values for responsive layouts.

  • PX to VW Converter – Convert pixel values into viewport-width units for fluid UI scaling.

Conclusion

The REM to PX Converter is more than just a utility – it’s a translator between scalable, accessible design and pixel-precise implementation. Whether you’re working on typography, spacing systems, blueprints for dev, or client deliverables, having accurate conversions keeps your work aligned, speedy and professional.

As an agency founder with multiple design streams, I’ve seen how skipping this step leads to misalignment, wasted time and frustrated hand-offs.

That’s why we built these converter tools, and now they’re here to support your workflow too.

Bookmark this tool, share it with your team, and integrate it into your style-guide process. With scalable units like rem and absolute units like px both in harmony, your designs become not just beautiful – but built for consistency, performance and precision.

Let’s keep your layouts pixel-perfect and yet fully responsive and future-ready.

Cheers,
Kuldeep