Reply To: Em-dash, En-dash, hyphen, ellipsis

I’ve set thousands of books over the years, and it is very rare to have space on either side of an em or en dash (in my experience). And we’ve never made an em dash 80 percent of it’s size. I do recall one publisher who preferred a thin space on either side of em dashes, but that was the exception. A lot of it depends upon which country it’s being set in. For example, the UK seems to use en dashes with a space on either side instead of em dashes. Some use spaced ellipses, while others use the actual ellipses charter (non spaced).

A good source of em dashes, en dashes, ellipses, etc., is the Chicago Manual of Style.