A pair of analysts at Evercore believe Facebook stock will rise to $60 after calculating a revenue estimate for Instagram, which is currently revenue free. Ken Sena and Andrew McNellis believe ads on Instagram could pull in $340 million in 2014.

Facebook recently added 15-second autoplay videos to Instagram, and 15 seconds is a traditional TV ad unit length.

Facebook stock has been on a tear this year, rising from $26 in July to hovering around $50 today.

The Evercore price target isn't based solely on revenue potential for Instagram, of course. Sena and McNellis believe Facebook's Q3 2013 revenues will come in stronger than expected from existing clients, the pair believe, based on their check of Facebook advertisers.

Analysts were surprised in Q2 2013, when Facebook revenue came in far above their expectations largely because Wall Street had not properly factored in mobile revenue to their models. This time around, Sena and McNellis believe analysts have not fully factored in Facebook's relationships with Datalogix and Acxiom, two companies that help advertisers take their offline data — lists of phone numbers, for instance — and use that as a targeting mechanism on Facebook.

Here's their chart on Facebook's revenue per user versus Google's. Lots of growth left, they believe:

Disclosure: The author owns Facebook stock.

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