It’s finally reaching the 1 billion figure. The Firefox Web browser since its first release back in 2004. That’s translate to about 684,000 downloads daily since then.

It is estimated the 1,000,000,000 downloads mark will be breached by Friday at noon GMT. The figure includes all versions of Firefox since the first release in 2004.

If a single user downloaded multiple copies for different computers, they are each counted in the total. And if a user goes to the Web site to download an update to an existing version, instead of waiting for the automatic download, that is counted as well. Automatic updates are not included in the total.

Firefox had 22.51% of the recorded usage share of web browsers as of May 2009, making it the second most popular browser in terms of current use worldwide, after Microsoft’s Internet Explorer.

Its current stable release is version 3.5.1, released on July 16, 2009.