A few weeks back the city's Budget and Legislative Analyst’s Office, at the behest of Supervisor David Campos, put out a report in which they attempted to estimate how many "commercial users" of Airbnb there are citywide — and by that they meant hosts who are keeping units off the long-term rental market because it's more financially advantageous to them to rent them out via Airbnb. The figure is hard to determine without Airbnb's help, but the report came up with some startling assertions such as a) between 29 and 40 percent of all available housing units in the Mission are currently being rented out via Airbnb instead, and b) there are something like 2,000 units citywide that are being rented by these "commercial hosts." Airbnb immediately responded to the report saying it came "from the same people who want to ban new housing in the Mission," and they've now put together their own report and crunched their own numbers, which naturally paint a less sensational picture about Airbnb usage across SF.

This retort, as it were, comes just before votes by the Board of Supervisors tomorrow on two different proposals that would effectively cap the number of nights per year that an Airbnb host is permitted to rent their unit on a short-term basis. Campos is pushing for a 60-day-per-year cap, while there's also a ballot measure upcoming that would make it a 75-day cap.

Per the Planning Department's earlier analysis, going by median rents in various neighborhoods, it would take about 257 days per year of Airbnb occupancy to out-compete what a landlord would get if they rented the same unit to a long-term renter. Taking that figure, they say, "from May 1, 2014 to April 30, 2015 only 3.2 percent of Airbnb entire unit listings in San Francisco were rented more than 257 days." And that represents just 0.6 percent of all vacant housing units citywide.

Furthermore, they calculate the median days per year it would take to break even with Airbnb versus a long-term renter is 211 days — less than Planning's estimate, but far more than the budget office's number, which was 59 days.

And they say that these so-called "commercial" units that are being rented at least that many days per year represent less than 1 percent of all housing units in the city, and 1.14 percent of all vacant units. Airbnb spokesperson Christopher Nulty clarifies that that is based on a 2013 figure for vacant units, which was 30,501 — so that means that by their estimate, 348 units are being kept off the market and rented as short-term rentals. That should be compared to the budget office's estimate of 2,000 units, and the real number is, perhaps, somewhere between the two.

Airbnb stresses that 211 nights per year is more than double the number of nights the average SF host rents their unit — that would be 90 nights per year, with the vast majority, 80 percent, renting their primary residence to help pay their rent or mortgage.

The new report concludes that "opponents have attempted to misuse data to mislead San Franciscans about an important issue that predated Airbnb’s existence," namely the problem of how expensive it is to live here, and how people rent their homes to help make ends meet. And, because it's Airbnb, they continue to stress the idea most people aren't taking advantage of the short-term rental economy for pure financial gain, keeping empty units off the long-term market. And that "home sharing has been the one thing making it possible for thousands of middle class families to stay in the city they love."

Nevertheless, you can prepare for these numbers to continue to be debated as we head toward possibly ending hosts' ability to rent their units all year long.

Previously: Study: Airbnb 'Commercial Hosts' Definitely Keeping Long-Term Rental Units Off the Market