Detailed within its Q2 2013 earnings release, Facebook announced it has passed 819 million mobile monthly active users (MAUs). These mobile users now collectively account for 41% of Facebook’s total ad revenue, or $656 million.

Compared to the company’s previous release back in May — when Facebook reported 751M mobile MAUs, and generated $375M or 30% of total ad revenue — Facebook is seeing strong growth.

When compared to 2012, the numbers look even better: Facebook’s monthly MAUs are up 51% year over year for Q2. Now, let’s observe Facebook’s mobile growth, starting in 2009:

fb mobile june 730x529 Facebooks mobile spike: 819M monthly users brought in $656M in Q2, 41% of ad revenue

For fun, let’s do some math: If Facebook brought in $656M this past quarter through its 819M mobile MAUs, then each one is worth approximately $0.80 cents to the company. Applying that same math to last quarter, however, places the worth of a single mobile MAU at just under $0.50. This calculation is certainly flawed — there’s no doubt mobile users represent varying value to Facebook’s ad network — but it still reveals that Facebook’s mobile users are growing in value to the company as they simultaneously grow in numbers.

Interestingly, Q2 marks Facebook’s third consecutive quarter in which more users accessed the site from a mobile device than they did from the Web. In total, Facebook now has 1.15 billion monthly active users and 699 million daily active users.