Microsoft officially (and confusingly) discloses Surface Pro storage figures

Microsoft officially (and confusingly) discloses Surface Pro storage figures

Summary: Microsoft's Surface Pro, which the company officially calls "a powerful PC in tablet form," went on sale today. On its website, Microsoft has officially disclosed how much data storage space you can expect to get from each model. Good luck translating the numbers.


Microsoft's Surface Pro went on sale today, with new product positioning and and some new official information about storage capacity.


Now that the Surface Pro is on sale, Microsoft has finally disclosed how much free space buyers of the new device can expect. No, those numbers aren't the ones you read last week. Some commentators were horrified when Microsoft mistakenly confirmed that the smaller Surface Pro would only have 23 GB of free disk space and the larger 128 GB model would be limited to 83 GB of storage.

As it turns out, those numbers are way off the mark. The actual figures, when expressed in the decimal system used to calculate the 64 and 128 GB total storage, are 32 GB and 96 GB, respectively. If you use the built-in tool to relocate the Recovery partition, the amount of free space available climbs to 40 GB for the Surface Pro 64 and 104 GB for the Surface Pro 128.

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But Microsoft has botched its messaging to potential buyers.


On its website, under the heading, “What are my storage options?” the company says the Surface Pro 64 GB model leaves “approximately 29 GB available for user content.” The 128 GB model, that page says, has about 89 GB available for personal data.

Both numbers, of course, exclude the Recovery partition, an 8 GB slice of space at the end of the SSD. That partition can be copied to a USB flash drive, increasing the available space to 37 GB and 97 GB, respectively.

A footnote leads to a detailed breakdown of available storage, which was just updated overnight. Confusingly, the numbers describing total storage (64 GB and 128 GB) are listed using the decimal system (billions of bytes). But all of the numbers for used storage space are reported using the Windows binary system, which makes them appear to be smaller than they are. (For a full explanation of the difference, see this post.)

Here’s the breakdown, directly from Microsoft's website, using the Windows binary system:

Category Surface Pro 128 Surface Pro 64
Total storage 119 59
Reserved for recovery tools -9 -9
Windows 8 Pro, built-in apps -21 -21
Available storage, via File Explorer 89 29

*All numbers in GB, as reported by Windows (binary system)

If you convert those numbers to the decimal system, so that they match the 128 and 64 on the box, in advertising, and on the device itself, you get these numbers instead:

Category Surface Pro 128 Surface Pro 64
Total storage



Reserved for recovery tools



Windows 8 Pro, built-in apps



Available storage



*All numbers in billions of bytes, rounded to nearest whole number

Bottom line: With the Surface Pro 128, you get almost exactly 75 percent of the total storage for data files and new apps. With the smaller 64 GB device, you get almost exactly 50 percent for user data and new apps. If you relocate the Recovery partition, those percentages increase to 81 percent and 62 percent, respectively.

Update: Here's a screen shot of the properties for the system partition on a new Surface Pro 128, freshly set up. Notice the decimal value for free space is slightly over 96 billion bytes.


The recovery partition takes up another 8.4 billion bytes. If you relocate it then total free disk space is equal to 104.5 billion bytes.

By the way, the used space on the Surface Pro includes a trial version of Office 2013, which occupies approximately 1.7 GB. If you activate it using a product key or an Office 365 subscription, the amount of free space doesn't change significantly, because the installer files are already present. If you don't want Office, you can uninstall it to reclaim its disk space.

When I checked in with Microsoft late this week, the text in this disclosure was still being reviewed by lawyers. It appears the technical and marketing teams didn’t have much of a say in the process. The footnote at the bottom of the page still mentions only Windows RT; it should also include Windows 8:

Storage size shown is based on decimal system (1 GB = 1 billion bytes) while Windows RT displays disk size using binary system (1 GB = 1,073,741,824 bytes). As a result, 1 GB (in decimal) appears as about 0.93 GB (in binary). Storage capacity is the same; it's just shown differently depending on how you measure a GB (decimal or binary).

Those numbers count only the included solid-state drive, a stock C400 mSATA part from Micron. Both Surface Pro models also include USB 3.0 ports and SD card slots, giving them access to essentially unlimited external storage. (The maximum SD card size is currently 64 GB, but larger cards are in the pipeline.) And of course, both devices are capable of connecting to network and cloud storage as well.

Update: Microsoft has now revised the language in that disclosure. In addition, I can confirm that the Surface Pro includes a trial version of Office 2013 that occupies about 2 GB of disk space. If you install Office, as most buyers probably will, the disk space usage will not increase.

The question for potential buyers, though, is this: How much local data storage do you really need?

Let’s ask the market: As of this morning, a few hours after the Surface Pro went on sale, Microsoft’s web site shows the 128 GB model as out of stock. Would-be buyers can’t even place an order.  By contrast, the 64 GB model is available for immediate shipment.

The situation is similar at Microsoft's retail partners, where the 128 GB models were out of stock everywhere I looked. Best Buy isn't taking orders from its website, but Staples is. They can ship a 64 GB model immediately, but you can't place an order for a 128 GB device.

I guess the market has spoken. They prefer at least 128 GB of storage for this "powerful PC in tablet form."

Update: It's worth noting that one model of the Surface RT also sold out early when it went on sale last October. But in that case it was the $499 32 GB model that buyers snapped up quickly. The 64 GB Surface RT continued to be available online. That suggests that buyers of the RT device were price-sensitive and were looking for something with a tablet-like price. By contrast, the initial sell-out of the higher-priced 128 GB Surface Pro suggests early buyers are spec-sensitive and are skeptical of the available storage in the 64 GB device.

In other words, buyers are treating the Surface RT like a tablet and the Surface Pro like a PC. 

Topic: Microsoft Surface

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  • Again, GB is officially equals to 1 billion bytes by *standard* for a long

    ... time already.

    Microsoft has to end this confusion by using proper measurements.

    Binary gigabyte = 2^30 = 1,073,741,824 bytes = 1 GiB, not 1 GB.
    • Correction: "... GB officially equals to ..."

      The subject.
    • The great thing about standards

      The great thing about standards is that there are so many of them. ;)

      The problem here is that Microsoft is mixing and matching two different measurements. That's a recipe for consumer confusion.

      Changing the built-in Windows tools so they report decimal instead of base 2 storage is the first step, but that would touch some of the lowest level components in Windows.
      Ed Bott
      • Confusion is the theme for Surface

        Their marketing may be confusing by reinterpreting data measurements, but at least Microsoft is being consistently confusing with Surface.

        Casual observers do not understand the difference between RT and Pro. To many folks the Pro is just an overpriced tablet, so they won't buy it - even though it is clearly the better choice for them.

        Perhaps Microsoft has found a new strategy for bringing down Apple that we aren't privy to.
        • Snake oil and snake oil salesman

          Snake oil and snake oil salesman.
          • Remember Zune HD?

            Meh. This is just like Zune HD Sold Out in 2009 according to MS PR. Give me numbers.
      • -

        anona nimos
    • Math is not the enemy

      I don't think there is any operating system that uses the decimal based notation to report drive space. The problem here is that we dumbed it down and turned megabytes into mibibytes instead of forcing people to do a little bit of math. Data storage is binary. Why would it be reported in any other way?
      • Ahem

        OS X has used decimal notation to report drive sizes since 2009.

        I wrote about it earlier this week. You must have missed it.
        Ed Bott
        • As does Linux

          Or at least current iteratins of Ubuntu
          • bean520-0b405....why bring up Ubuntu

            This is all about Ed sticking up for Microsoft again.....ever herd the story that ..."TWO WRONGS DON'T MAKE IT RIGHT".....that all Ed doing by bringing up old stories he wrote..............

            PS Ubuntu 13.04 Alpha is just crusing along...................
            Over and Out
      • What is needed is a cross platform standard way.

        For a consumer it probably makes no difference which method of reporting is used. What is important to them is to have storage reported consistently across all the devices they use. This lets them compare apples to apples when transferring files from one device to another.

        It probably would have been better if hard drive manufacturers had not used decimal numbers to inflate the size of their drives - so I would not still have to be explaining to people why the 640 GB drive in their PC is really 596 GB. But they did and now we are stuck with this system that makes sense to geeks but no one else cares about - they just want sizes reported consistently across the board.
        • binary

          In my opinion binary notation is the right way, not decimal.
        • Re: What is needed is a cross platform standard way.

          There is, and it's even an official standard:

    • Along with using proper SI system instead of imperial

      But only after US abandons all these crazy feet, inches, miles, Fahrenheit degrees, gallons, pounds, and ounces (and I don't even want to know what fl. oz. means) :)

      I think Microsoft should have called it Surface Pro 120 and Surface Pro 60. Due to marketing reasons, MS most probably will soon switch to decimal system too. Windows 9?
      • Not happening anytime soon

        A lot of people in the USA love their imperial unit measurement, so don't expect a metric change in your lifetime. I'd love to see it happen, but it won't.
        • Re: A lot of people in the USA love their imperial unit measurement

          Ironic, isn't it, since that "imperial" refers to the British Empire, which I thought the USians fought a war to be free of. Yet here they are, still clinging to one outmoded aspect of it in a most peculiar way...
      • That argument's been going on for a long time

        AFAICT, the only reason why the UK gave up its customary system because it was a requirement for joining the EEC (now the EU). It wouldn't surprise me if Thomas Jefferson tried to get the metric system adopted when he was President in the early 1800s, but Congress wouldn't go along (apparently, changing the side of the road Americans drove on was radical enough).

        But we are seeing slow adoption of metric units in both commerce and academia. I notice that the skeins in my wife's new yarn shop show weights in both grams and ounces. Metric measurements have been standard in U.S. science since at least the 1970s when I was in high school.

        I figure we'll adopt the metric system when we're good and ready and not one second before.
        John L. Ries
      • Never gonna happen

        When I was in 4th grade we started learning the metric system because the U.S. was going to change over by the time we were in high school. I'm 55 now and still waiting.
        • One more thing

          We have more people in the U.S. who believe in angels than we have that believe in evolution.

          So I repeat, never gonna happen.