MM to PX Converter
1 mm = 3.7795 px at 96 DPI
This MM to PX Converter instantly translates millimeters to pixels and back, using any DPI value you choose.
Designers working across print and screen constantly hit this wall: your source file is in mm, your editor wants px. This tool closes that gap. No formulas to remember. No spreadsheets.
Key features:
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Bidirectional conversion -- type in either field, the other updates instantly
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DPI presets for the most common scenarios: Screen (96), Retina (144), Print (300), HD (72)
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Custom DPI input for any device or print spec
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Quick-fill presets for standard sizes: A4, A5, business card, US Letter, 1 inch
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Precise and rounded results shown side by side
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Copy to clipboard on any result with one click
Short inputs, instant output. The live formula at the bottom always shows the exact conversion rate at your current DPI, so you understand the math, not just the answer.
What is MM to PX Conversion
MM to PX conversion is the process of translating a physical length in millimeters into the corresponding number of pixels used on a digital screen or in a print workflow.
A millimeter is an absolute unit. It never changes regardless of the device showing it.
A pixel is different. It's a relative unit whose physical size depends entirely on the screen density of the display it lives on.
That gap is the core problem. You can't convert one to the other without a third value, which is DPI (dots per inch) or PPI (pixels per inch). It connects the physical and digital worlds.
MM to PX Formula
The formula is:
Pixels = Millimeters × (DPI ÷ 25.4)
The 25.4 constant is the number of millimeters in one inch. DPI tells the formula how many pixel dots fit inside that inch.
Why 25.4
One inch equals exactly 25.4 mm. Since DPI and PPI are both defined per inch, the formula first converts millimeters to inches by dividing by 25.4, then multiplies by the pixel density.
How DPI Affects the Result
The same millimeter value produces very different pixel counts depending on your target DPI. Here's what 10 mm converts to across common resolutions:
|
DPI / PPI |
Use Case |
10 mm in Pixels |
|---|---|---|
|
72 DPI |
Screen (legacy Mac) |
28.35 px |
|
96 DPI |
Web / CSS standard |
37.80 px |
|
150 DPI |
Medium-res print |
59.06 px |
|
300 DPI |
High-quality print |
118.11 px |
|
600 DPI |
Professional offset |
236.22 px |
MM to PX Conversion Table
Quick reference for the most common millimeter values at 72, 96, and 300 DPI.
|
MM |
72 DPI |
96 DPI |
300 DPI |
|---|---|---|---|
|
1 mm |
2.83 px |
3.78 px |
11.81 px |
|
5 mm |
14.17 px |
18.90 px |
59.06 px |
|
10 mm |
28.35 px |
37.80 px |
118.11 px |
|
25 mm |
70.87 px |
94.49 px |
295.28 px |
|
50 mm |
141.73 px |
188.98 px |
590.55 px |
|
100 mm |
283.46 px |
377.95 px |
1181.10 px |
|
210 mm |
595.28 px |
793.70 px |
2480.31 px |
|
297 mm |
841.89 px |
1122.52 px |
3507.87 px |
What is a Pixel
A pixel is the smallest controllable unit of a digital image or display. It carries no fixed physical size.
On a low-density screen, one pixel is a larger dot. On a high-density display, it's much smaller.
This variability is exactly why converting millimeters to pixels always requires a DPI or PPI value.
Logical Pixels vs Physical Pixels
Modern devices distinguish between logical and physical pixels.
Device Pixel Ratio (DPR) links the two: logical resolution = physical resolution ÷ DPR.
A screen with 1024×768 physical pixels and a DPR of 2 has a logical resolution of 512×384. CSS works with logical pixels, not physical ones.
CSS Pixels and the 96 PPI Standard
The W3C defined the CSS reference pixel at 96 PPI. This became the baseline for all browser rendering and is why most online converters default to 96 DPI.
At 96 PPI: 1 mm = 3.7795 px. That's the number you'll see most often in web design tools and CSS documentation.
What is a Millimeter
A millimeter is one-thousandth of a meter. It's an absolute unit of length in the metric system, meaning it always represents the same physical distance regardless of screen, device, or medium.
This is the key difference from a pixel. Whether you measure 10 mm on paper or on a ruler, it's always 10 mm. A pixel changes its physical size depending on the display it lives on.
In print design, millimeters are the standard for dimensions. A4 paper is 210 × 297 mm; a standard business card is 85 × 55 mm. When those dimensions need to become digital assets, a mm-to-px conversion is required.
DPI vs PPI
DPI (dots per inch) refers to print resolution - specifically how many ink dots a printer places per inch.
PPI (pixels per inch) is the correct term for screens. It measures how many pixels fit into one inch of a display.
In practice, most converters and design tools use both terms interchangeably. For screen work, PPI is technically accurate; for print work, DPI is the right call.
MM to PX for Web Design
At 96 PPI - the W3C standard for CSS - 1 mm equals 3.7795 px.
Brand guidelines and client briefs often specify dimensions in millimeters. A logo set at 40 mm wide needs to be converted before you can use it in CSS, Figma, or Sketch.
Using MM to PX in CSS
CSS does accept mm as a unit, but browser rendering of physical units is inconsistent across devices.
Converted px values are more reliable. Use the formula, get a pixel value, and hard-code it.
MM to PX in Figma and Sketch
Both tools allow manual unit input. Set your canvas to pixels, convert your mm spec using 96 PPI, and enter the result directly into the width, height, padding, or margin field.
Figma also has a built-in unit switcher in the design panel - though it defaults to 96 PPI, so verify this matches your project specs before relying on it.
MM to PX for Print and Graphic Design
300 DPI is the standard for high-quality print. Professional offset printing typically uses 600 DPI.
At 72 or 96 DPI, print dimensions produce far fewer pixels than the physical output requires - which is why print assets always look blurry when opened at screen resolution.
Business Card Size in Pixels
A standard business card (85 × 55 mm) at 300 DPI converts to 1004 × 650 px.
At 96 DPI (web only), the same card is 321 × 208 px - not suitable for print.
A4 Paper Size in Pixels
A4 (210 × 297 mm) converts as follows:
|
DPI |
Width |
Height |
|---|---|---|
|
72 DPI |
595 px |
842 px |
|
96 DPI |
794 px |
1123 px |
|
300 DPI |
2480 px |
3508 px |
Common Print Format Conversions
|
Format |
Size (mm) |
At 300 DPI |
|---|---|---|
|
Passport photo |
35 × 45 mm |
413 × 531 px |
|
ID card |
85.6 × 54 mm |
1011 × 638 px |
|
US Letter |
216 × 279 mm |
2551 × 3295 px |
|
A3 Poster |
297 × 420 mm |
3508 × 4961 px |
Common MM to PX Values at 96 PPI
At the 96 PPI web standard, these are the most searched conversions:
|
Millimeters |
Pixels (96 PPI) |
|---|---|
|
1 mm |
3.78 px |
|
2 mm |
7.56 px |
|
3 mm |
11.34 px |
|
5 mm |
18.90 px |
|
10 mm |
37.80 px |
|
20 mm |
75.59 px |
|
50 mm |
188.98 px |
1 mm ≈ 3.78 px is the number worth memorizing for everyday web design work.
How to Convert MM to PX Without a Calculator
Three steps:
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Note your millimeter value
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Decide your DPI (96 for web, 300 for print)
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Apply: px = mm × (DPI ÷ 25.4)
Quick worked example: 25 mm at 96 DPI → 25 × (96 ÷ 25.4) → 25 × 3.7795 → 94.49 px
No tool needed. The math takes about 10 seconds with a basic calculator.
PX to MM Conversion
The reverse formula: Millimeters = Pixels × (25.4 ÷ DPI)
At 96 DPI: 100 px × (25.4 ÷ 96) = 26.46 mm
Use this when you're pulling dimensions out of a digital file and need to match them to a physical print spec. The PX to MM converter handles this automatically if you'd rather skip the manual calculation.
Other unit converters you might need alongside this one:
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PX to CM - for metric print layouts
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PX to Inches - for US print specs
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PX to PT - for typography and font sizing
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PX to REM - for scalable CSS units
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CM to PX - when working from centimeter specs
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Inch to PX - for US measurement inputs
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PT to PX - converting point sizes to pixels
MM to PX for Different Screen Resolutions
The same millimeter value produces different pixel counts on every device. This is device pixel ratio at work.
|
Device |
PPI |
10 mm in Pixels |
|---|---|---|
|
Standard desktop monitor |
96 PPI |
37.80 px |
|
MacBook Pro (Retina) |
227 PPI |
89.37 px |
|
iPhone 15 Pro |
460 PPI |
181.10 px |
|
4K desktop display |
163 PPI |
64.17 px |
CSS logical pixels normalize this. A 38 px CSS value renders at a consistent visual size across all of these screens - the browser handles the DPR scaling behind the scenes.
This is why you don't need to create different px values for different screen densities when writing CSS. You do need to account for DPR when exporting image assets, though. A UI image that looks sharp at 1× will appear blurry on a 2× or 3× Retina display unless you export at the higher resolution.
FAQ on Mm To Px Converters
How do I convert mm to px?
Multiply your millimeter value by your DPI, then divide by 25.4.
At the 96 DPI web standard: 1 mm = 3.78 px. For print at 300 DPI: 1 mm = 11.81 px. Most online calculators handle this instantly.
What DPI should I use for web design?
Use 96 DPI. That's the W3C CSS reference pixel standard used by all major browsers.
It's the default in Figma, Sketch, and most mm to px calculators. Only change it if you're targeting a specific device or non-standard display resolution.
How many pixels is 1 mm?
At 96 DPI, 1 mm equals 3.7795 px.
At 300 DPI (high-quality print), 1 mm equals 11.81 px. The pixel value always depends on your target DPI or PPI - there's no single universal answer.
What's the difference between DPI and PPI?
PPI (pixels per inch) refers to screen resolution. DPI (dots per inch) refers to print output.
Most converters treat them as interchangeable. Technically, use PPI for digital screens and DPI for printers and physical media.
Why can't I just use mm directly in CSS?
You can write mm in CSS, but browser rendering of physical units is unreliable across devices.
Pixel values are consistent and predictable. Convert your mm spec to px first, then use that value in your stylesheet.
How do I convert mm to px for print?
Use 300 DPI for standard print quality, 600 DPI for professional offset.
Apply the formula: px = mm × (DPI ÷ 25.4). A 300 DPI A4 page (210 × 297 mm) produces 2480 × 3508 px - the standard for print-ready files.
What is device pixel ratio and does it affect mm to px conversion?
Device pixel ratio (DPR) is the ratio of physical pixels to logical CSS pixels on a screen.
It affects how assets render visually, but not the mm to px formula itself. CSS works with logical pixels; the browser handles DPR scaling automatically.
How many pixels is a standard business card in mm?
A standard business card is 85 × 55 mm.
At 300 DPI for print, that converts to 1004 × 650 px. At 96 DPI for screen use only, it's 321 × 208 px - not suitable for physical printing.
Is 96 DPI the same as 96 PPI?
Yes, in digital contexts they refer to the same value.
96 PPI is the CSS pixel density standard set by the W3C. The terms DPI and PPI are used interchangeably in most design tools, converters, and browser documentation.
How do I convert px back to mm?
Use the reverse formula: mm = px × (25.4 ÷ DPI).
At 96 DPI, 100 px = 26.46 mm. Use the PX to MM converter to skip the manual calculation when working from digital dimensions back to physical print specs.