Pixels and points

The relationship of pixels to points depends on the number of pixels per inch (ppi), which is typically some 'standard' value corresponding to default screen fonts. For example, MS Windows has two standard sets of screen fonts initially designed for IBM display systems: 'small' (VGA) and 'large' (8514/A). 'Small' fonts are 96 ppi, 'large' are 120. Macintosh operating systems prior to OS X v10.4 render type at a nominal 72 ppi, i.e. one pixel = one point. Windows and newer Mac OS displays with scalable screen fonts allow fine tuning of ppi to suit user preferences.

The side-by-side text blocks below compare font-size specified in pixels on the left with font-size specified in points on the right. When ppi corresponds to your display, the font-size and line-height in the two columns should correspond closely (exactly when your display is 72 or 96 ppi). This page is currently composed for 96 ppi. Your display computes to  .
Enter your display's ppi here: and click to view results.

This text has a font-size of 24 pixels and a line-height of 40 pixels. The baseline to baseline distance should equal two grid squares. On a display where 96 pixels equals one inch, this font should be the same size as that in the right column. This text has a font-size of 18 points and a line-height of 30 points. On a display where 96 pixels equals one inch, both the baseline to baseline distance and the font size should be the same as those in the left column.

Note that the accuracy of fractional point measurements may vary with browser.

David Perrell