What is the em font-size unit? How much is it in pixels?

by

Despite what you may read elsewhere, there is no direct relationship between em and px.

As one of the links states:

the “em” value is based
on the width of the uppercase M

So it’s going to be different for every font. A narrow font might have the same height (in px) as an extended font, but the em size will be different.

EDIT three years later:

There are now lots of sources which say that 1em = font size (in px). That is, when you write font-size:16px, then 1em = 16px. This still doesn’t agree with the Adobe source (which says 1em = the font size in pt), but in either case it seems bizarre; the em size would be far too large with condensed fonts and far too small with extended fonts.

I’m going to make some test pages and see for myself.

And also:

I see that nobody (including me) actually answered the question (which was kind of hidden):

I also read somewhere about some ie bug and to overcome that set body font-size to something

According to this page, you need to add this to your css: html{ font-size:100%; }. That page is six years old, and I haven’t read the (hundreds) of comments, so I don’t know if it’s still relevant.

More Related Contents:

  1. Font scaling based on width of container
  2. Responsive font size in CSS
  3. How is font size calculated?
  4. Font-size issues comparing chrome and Firefox
  5. Font size in CSS – % or em? [duplicate]
  6. How can I change the font-size of a select option? [duplicate]
  7. What does font-size really correspond to?
  8. Some font-size’s rendered larger on Safari (iPhone)
  9. Font scaling based on size of container
  10. CSS: 100% font size – 100% of what?
  11. how to override font boosting in mobile chrome
  12. Specify width in *characters*
  13. How to create one vertical column in between rows in Flexbox [closed]
  14. How can i make this wave effect on both bottom and top
  15. How to apply a CSS filter to a background image
  16. Why is a flex item limited to parent size?
  17. Transparent text cut out of background
  18. Remove blue border from css custom-styled button in Chrome
  19. How do I use /deep/ or >>> or ::v-deep in Vue.js?
  20. React.js inline style best practices [closed]
  21. Internet Explorer’s CSS rules limits
  22. CSS: Set a background color which is 50% of the width of the window
  23. IE8 :nth-child and :before
  24. Disable zoom on a div, but allow zoom on the page (an alternate div)
  25. CSS Selector for
  26. Make scrollbars only visible when a Div is hovered over?
  27. Can I define a class name on paragraph using Markdown?
  28. How to add a margin to a table row [duplicate]
  29. minmax fails (invalid property value)
  30. Select specific element before other element

Leave a Comment