Even the most diehard of Microsoft (MSFT -3.71%) fans will admit its old Surface RT tablet was an unmitigated disaster. From lackluster sales to massive inventory write-offs, former Microsoft CEO Steve Ballmer's efforts to make a splash in mobile devices and services didn't exactly start off with a bang. And catching tablet sales leader Apple (AAPL -0.08%) with the Surface RT? Not even close.

But just how bad were the Surface RT sales, and that of its future iterations? According to some recent computations from Computerworld and a tech industry analyst, about $1.7 billion in red ink bad. Of course, in Microsoft's recently completed fiscal 2014 the company generated close to $87 billion in revenue, so $1.7 billion isn't a ton, at least as a percentage of overall sales. But regardless of total revenues, that kind of loss -- assuming it's close to being accurate -- is still a bitter pill to swallow.

What's the problem?
Though the $1.7 billion loss seems at first to be a huge figure, if Surface RT sales in the first year are any indication, it may not be too far off the mark. Microsoft aficionados will (painfully) recall it was about this time in 2013, just a year after first introducing the Surface RT to the masses, that Microsoft announced it was taking a $900 million write-off because of excess RT inventory.

Right around the time Microsoft was announcing its $900 million Surface RT hit, its tablet sales actually started to pick up; that's the good news. Unfortunately, it took huge price reductions to get consumers interested in Microsoft's foray into tablets. After cutting the price by 30%, and even more for schools and businesses, the Surface RT finally began moving off the shelves. But by that time, the damage had been done, and with those kind of markdowns, margins were taking a beating.

By the numbers
Getting to the $1.7 billion loss figure was a bit convoluted, in that the Computerworld pundit and industry analyst had to estimate expenses associated with the manufacturing and distribution of Surface tablets. Why? Because unlike previous filings with the Securities and Exchange Commission, Microsoft chose to not disclose the cost of generating Surface's $409 million in revenue last quarter. Microsoft's decision to stay mum on costs associated with Surface sales in and of itself could be construed as a telling sign.

Without specific expense information associated with Surface tablets from Microsoft, estimating losses required digging through recent SEC filings and "earlier reports." Based on the results of that research, Computerworld's computations determined that it cost Microsoft about $772 million last quarter to manufacture and sell a mere $409 million in Surface tablets.

The analyst included in Computerworld's loss tally put the expense figure at slightly less $733 million last quarter. Using similar methodologies, the loss calculations were then backdated using past quarterly financial data, ultimately arriving at the $1.7 billion total. It should be noted that the overhead costs in Microsoft's recently completed fiscal 2014 Q4 included write-offs for the never-released Surface Mini, and production expenses for the newly released Surface Pro 3.

The road ahead
Considering the nearly $1 billion loss Microsoft took following the Surface's first year in production, the $1.7 billion may not be far off the mark. However, going forward, Microsoft thinks it may have finally found the answer to Apple's tablet industry leading iPad: the Surface Pro 3. Shortly after making it available to the masses in select markets, Microsoft recently announced the Pro 3 will launch in 25 more regions at the end of August, including China, the U.K., as well as several European and Asian countries.

Is there light at the end of the Surface Pro 3 Tunnel? Based on slowing sales of Apple's iPad, Microsoft would like to think so. At 13.3 million units sold in Apple's fiscal Q3, you have to go back about two years to find a quarter that the iPad sold so poorly. Of course, Microsoft wouldn't complain if it moved over 13 million Surface Pro 3 pseudo-tablets, but it's the new kid on the tablet block, not the established leader that Apple is.

Final Foolish thoughts
Even with declining iPad sales, Microsoft's Surface Pro 3 has a long hill to climb. Whether older iterations of Surface have in fact lost $1.7 billion or not, it's safe to say Microsoft would prefer to look forward at what the Pro 3 can accomplish in the global tablet market, rather than look back at the mess that was the RT.