Netflix’s 10 Year Sustained Bandwidth is 200 Gigabits Per Second!

Today Netflix announced that they delivered their two billionth DVD, an impressive milestone. This brought to mind something we learned in the early days of Excite, which was to never underestimate the bandwidth of physical storage media sent via UPS, the USPS or FedEx. When we opened our second datacenter circa 1996 (on the east coast in one of AOL’s datacenters) we quickly found out that it was faster, cheaper and more reliable to simply FedEx overnight an archived backup tape copy of our search index to the east coast mirror site than to transfer the files over the internet.

I’ve always thought that Netflix’s business was a brilliant bet that the bandwidth and quality of a rental experience powered by DVDs sent via USPS was going to be cheaper and exceed the capabilities of on-demand via the internet for much longer than people were expecting, and of course this turned out to be true. And now that internet tech is finally catching up to the low tech method of shipping atoms full of bits around the country, I think Netflix has done a brilliant job with their internet strategy and distribution partnerships, which should enable a graceful (and still longer-term than people expect) transition from postal delivery to internet delivery.

So when I saw the announcement of the two billionth DVD delivered, I decided to do a quick and dirty back-of-the-envelope calculation of how much data Netflix has delivered to customers in the roughly 10 years since their subscription service launched. (Apologies in advance to all the sticklers out there who might point out the imprecision of this calculation since I’m using factors of 1,000 instead of 1,024 to measure my gigabytes and petabytes.) Here goes:

A DVD has a max capacity of 4.7 gigabytes. Since Netflix also ships TV shows and the like, which don’t fill a DVD to capacity, let’s assume that the average DVD contains 4 GB of data. So, that means they’ve delivered eight billion gigabytes, or eight million terabytes, or eight thousand petabytes, which boils down to an average of 800 petabytes per year over a ten year period. Multiply that by 8 bits per byte and divide by 31,536,000 seconds per year, and you get 202,942,669,000 bits per second, or a sustained ten-year average bandwidth of 200 gigabits per second.

Of course, that’s an average spread evenly over 10 years, and today’s outgoing bandwidth from Netflix via the USPS is many times higher, given the ramp from zero DVDs shipped in the early years and given the fact that Netflix is now shipping Bluray discs, which hold 50GB vs. the 4.7GB on a traditional DVD. And, finally, given they are actually delivering movies via the net, they are now using actual net bandwidth instead of theoretically derived, USPS-enabled bandwidth, though I’m sure their actual bandwidth consumption is still dwarfed by the discs in the mail.

But still, I was surprised by the 200 Gbps number and had to check my calculations a few times to make sure I was right. And it is conceivable that that means that their theoretical bandwidth today could be in the terabit per second range. Golly.

  • Ross

    That's great Ryan – the only thing I'd add is your calculations are off by roughly half, a comerical DVD is 8.5 GB, not 4.7 (they are dual layer). So really it's just about double this, again in very rough math. But holy wow, who know the USPS could sustain such bandwidth!

  • Chris McGarry

    Very interesting observation! Following on Ross' comment, average feature size (the movie itself minus bonus DVD content) is prob around 6 GB.

  • Craig Hughes

    Not only are most commercial video DVDs dual-layered, many are also double-sided, with a letterbox version on one side and pan-and-scan on the reverse, for a total of 16GB. So Netflix could be up around 1/2 terabit per second average, depending on the ratios.

  • Deyan Vitanov

    Well, one could take the opposite view and say that actually encoded movies are about ~700MB a piece (using Xvid or DivX or similar) – which would make sense if you are making a comparison with online transfer, because no one would start transfering raw DVDs. Great post!

    • Craig Hughes

      Yeah, who would transfer whole DVDs online? Actually probably gives a decent sense for how many DVDs are single-layer vs dual for estimating Netflix's offline bandwidth.

    • I think you've missed the point slightly which was about bandwidth _actually_ consumed.

  • Great post! Here is some other good reading in the matter. Streamfile's take on file transfers and shuffling data in general.

  • Thanks for all the comments, and for pointing out the dual-layer issue as well as the fact that if served online, they'd be compressed using a more efficient codec, which probably means the average size of a video in a real-world streaming situation is probably closer to 1GB.

    Even if you drop my 4GB per disc estimate by a factor of four, and then increase to what Netflix's actuall daily volume is *today* (as opposed to a 10 year average), those two factors probably cancel each other out, and you probably wind up with something in the neighborhood of my original estimate of 200 Gbps if Netflix were actually serving all of their videos on demand today. And I don't think there's many (maybe YouTube?) sites out there today that could claim that kind of throughput.

    • Heh. Assuming a linear increase from 0 DVDs ten years ago to max today Netflix are shipping out 3200 petabyte of data this year. That is around 755 gigabits per second or 12 DVDs delivered every second, 24/7 for a whole year.

  • the 200 Gbps number!It let me very surprised as well.