Typography Unit Converter
Convert between typography and CSS units: point (pt), pica, pixel (px), em, rem, inch, cm, and mm. Adjust DPI for accurate screen-to-print conversions. See also Length Converter.
Point (pt)
12
Pica (pc)
1
Pixel (px)
16
Inch (in)
0.166667
Centimeter (cm)
0.423333
Millimeter (mm)
4.233333
Em
1
Rem
1
How the Typography Converter Works
This tool converts between eight common typography and CSS units using the PostScript point as the base unit. Physical units (point, pica, inch, cm, mm) have fixed relationships. Screen units (pixel) depend on the display's DPI (dots per inch). Relative units (em, rem) depend on the base font size. Adjust the DPI and base font size settings for accurate conversions.
Conversion Formulas
1 inch = 72 points = 6 picas = 25.4 mm = 2.54 cm
1 pica = 12 points
1 pixel = 72 / DPI points (at 96 DPI: 1px = 0.75pt)
1 em = base font size in points
1 rem = root font size in points
Example (at 96 DPI, 16px base)
16px = 16 × (72/96) = 12pt
12pt = 1pc (pica)
12pt = 12/72 = 0.166667 inches
12pt = 12 × (25.4/72) = 4.233333 mm
16px = 1em = 1rem (when base = 16px)
Typography Unit Reference Table
| Unit | Abbreviation | Equals (in points) | Use Case |
|---|---|---|---|
| Point | pt | 1 | Print typography, PDF |
| Pica | pc | 12 | Print layout, InDesign |
| Pixel | px | 0.75 (at 96 DPI) | Screen/web design |
| Inch | in | 72 | Print, physical media |
| Centimeter | cm | 28.3465 | Metric print |
| Millimeter | mm | 2.8346 | Metric print |
| Em | em | Relative to parent font | CSS responsive sizing |
| Rem | rem | Relative to root font | CSS responsive sizing |
Screen vs. Print Typography
Print:Uses absolute units (points, picas, inches, cm, mm). A 12pt font is always the same physical size on paper regardless of the printer's resolution. The standard PostScript point is exactly 1/72 of an inch.
Screen:Uses pixels as the primary unit. The physical size of a pixel depends on the display's DPI. At 96 DPI (standard Windows), 1px ≈ 0.26mm. At 144 DPI (Retina), 1px ≈ 0.18mm. CSS pixels are reference pixels — on high-DPI screens, one CSS pixel may map to multiple device pixels. This is why the DPI setting matters for px ↔ pt conversions.
Technical Details
The PostScript point (1/72 inch) is the standard in digital typography and CSS. The older Didot point (0.376mm) and American point (0.3514mm) are rarely used today. CSS defines 1in = 96px = 72pt = 6pc = 2.54cm = 25.4mm. The em unit is relative to the computed font-size of the element's parent; rem is relative to the root element's font-size (typically the <html> element, defaulting to 16px in most browsers).
Frequently Asked Questions
What DPI should I use?
For standard screens, use 96 DPI (Windows default) or 72 DPI (macOS legacy). For print, use 300 DPI (standard print) or 150 DPI (draft). For Retina/HiDPI displays, the CSS pixel ratio handles scaling automatically.
What is the difference between em and rem?
Em is relative to the parent element's font size, so it compounds when nested. Rem is always relative to the root element's font size, making it more predictable. Most modern CSS frameworks prefer rem for consistent sizing.
Why is 16px the default base font size?
All major browsers set the default root font size to 16px. This means 1rem = 16px by default. At 96 DPI, 16px = 12pt, which is a comfortable reading size for body text on screen.
Should I use px or rem in CSS?
Use rem for font sizes and spacing to respect user accessibility settings (users can change their browser's default font size). Use px for borders, shadows, and other decorative properties where exact pixel control is needed.