Converting font sizes from pixels or points to ems

By John Dobson, University of Winnipeg Library

The following chart shows correspondences in font sizes as measured in pixels, points, and ems, as rendered in Internet Explorer, or Netscape 6 (with the browser’s text size at the normal setting). Sizes are calibrated to screen display, and may require adjustment for purposes of printing. Font sizes as measured in ems are about 10% larger in Netscape 4. Larger sizes may be extrapolated from the values given here.

The formula for converting pixels to ems is: ems = 0.05 * Int((5*pixels + 1)/4)

pixels points ems
1 0.5, 1 0.05
2 1.5 0.10
    0.15
3 2, 2.5 0.20
4 3 0.25
5 3.5, 4 0.30
6 4.5 0.35
    0.40
7 5, 5.5 0.45
8 6 0.50
9 6.5, 7 0.55
10 7.5 0.60
    0.65
11 8, 8.5 0.70
12 9 0.75
13 9.5, 10 0.80
14 10.5 0.85
    0.90
15 11, 11.5 0.95
16 12 1.00
17 12.5, 13 1.05
18 13.5 1.10
    1.15
   
pixels points ems
19 14, 14.5 1.20
20 15 1.25
21 15.5, 16 1.30
22 16.5 1.35
    1.40
23 17, 17.5 1.45
24 18 1.50
25 18.5, 19 1.55
26 19.5 1.60
    1.65
27 20, 20.5 1.70
28 21 1.75
29 21.5, 22 1.80
30 22.5 1.85
    1.90
31 23, 23.5 1.95
32 24 2.00
33 24.5, 25 2.05
34 25.5 2.10
    2.15
35 26, 26.5 2.20
36 27 2.25
37 27.5, 28 2.30
38 28.5 2.35
http://library.uwinnipeg.ca/people/dobson/portfolio/documents/font_conversion.html