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Is USB or WIFI faster when syncing an iPhone 4 with iOS 5 to iTunes?

This SuperUser answer suggests that Wireless N might be faster than USB 2: http://superuser.com/questions/288705/speed-comparison-usb-vs-wireless-n-vs-cat-6

Note: iPhone 4 is 802.11b/g/n Wi-Fi (802.11n 2.4GHz only)

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6 Answers 6

up vote 7 down vote accepted

USB 2.0 is faster, but Wi-Fi is better.

In practice, Wi-Fi will be superior to USB for syncing and backup since you don't have to worry about plugging it in. It can start as soon as you enter the network, throttle itself based on CPU/iOS activity. You can even start on WiFi and connect your iOS 5 device to USB and syncing will continue at faster speeds if WiFi proves to be slow for a particular sync session.

My experience is the devices can do their thing and sync in the background without me waiting for them and I'm almost always the slowest peg in the process. :-)

However, USB 2.0 speed is faster than 802.11n both in theory and in practice. See this chart from a very nice Apple Insider article on relative speeds relating to Time Capsule performance. The one area where USB (or any other wired connection whether it's USB 2.0, 3.0, FireWire or Thunderbolt) is better than Wi-Fi is latency. If your sync session is largely lots of little checks and no appreciable time is spent waiting for large files to transfer, then the wired connection could be much faster if your sessions are shorter than 15 to 30 seconds in length. Here's another nice article explaining how even a slow USB 2.0 connection can be fast enough for some demanding data transfers: http://www.apogeedigital.com/knowledgebase/quartet/why-doesnt-quartet-use-usb-3-0/

Image of graph from AppleInsider article comparing the theoretical and actual speeds of eSATA, USB 2.0, 10/100 Fast Ethernet, 10/100/1000 Gigabit Ethernet, 802.11g WiFi, and 802.11n WiFi. AppleInsider: Exploring Time Capsule: theoretical speed vs practical throughput

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NEW: BETTER SOLUTION:

If set up optimally, is USB or WIFI faster when syncing an iPhone 4 with iOS 5 to iTunes?

Wi-Fi is MUCH FASTER.

Lifehacker and company are wrong IF things are set up well/optimally!!

Optimal: Use 2.4 GHz Wi-Fi ONLY between the iDevice and the router. Use a wired (Fast or Gigabit) Ethernet connection or 5 GHz between the router and PC/Mac.

USB 2 is 12 Mbit/s (max), but one can sync over Wi-Fi 802.11n, at much higher speeds, if you avoid heavy contention for the Wi-Fi bandwidth. I just ran some tests (6 test runs, plus warm-ups) and was seeing iTunes sync speeds close to USB 2's max over a cable, and 2-4 times that speed (26Mbps to 50 Mbps) when connecting via a wired (gigabit ethernet) to a router and then over Wi-Fi to an iPhone 4S (that is, one wired hop and one wireless hop). (When sending large files to the iPhone. Short distance, 2.4 GHz 802.11n.) I also found that the basic no-op sync when nothing had changed was slightly faster over a well- configured Wi-Fi connection than over USB 2 (apple brand cable; no hub).

WHY? Data sent purely over Wi-Fi via a Wi-Fi router between a PC/Mac and an iDevice will result in heavy contention, as the data has to make two wireless hops, and Wi-Fi routers generally don't buffer well in that situation That's why a VoIP phone call using WiFi and bluetooth simultaneously is so often choppy: The WiFi and bluetooth are often competing for the same 2.4 GHz spectrum at the same time. This is also why most folks are getting poor iTunes throughput with Wi-Fi.

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In my experience, syncing at a variety of times, with an 802.11n network, USB is approximately 4x faster than WiFi.

If you're in the middle of a WiFi sync and it's taking too long, you can connect the USB cable and the sync will complete over the (much) faster USB connection.

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In my experience, USB sync is much faster than WiFi sync over my 802.11n AirPort, which can become an issue when I've recorded video. I was hoping that WiFi syncing meant my phone would auto-sync whenever I arrive home, but in reality it does not start syncing until you plug it in to charge within WiFi range. The upside is: I now sync whenever I plug my phone into any power brick in the house.

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Lifehacker did a pretty thorough write up of wireless syncing. In short - WiFi takes longer, but it's not too bad.

EDIT: Giant caveat - they only tested this over 802.11g. I imagine USB might still be faster, just because even though the iPhone storage is flash, we don't really know what its actual write speeds are.

While music and movies take 13 times longer over Wi-Fi than over USB, it's still a relatively short amount of time—6 and a half minutes for 4 albums isn't bad. If you aren't rushing out the door, it's certainly worth the "not getting out of your chair" factor, and if you're only syncing one or two albums, it'll be even faster. This benefit grows with something like the iPad, which is more difficult to just keep docked at your computer all the time—instead of finding it and bringing it to your computer all the time, you can just hit the sync button on either device and let it go to town.

Overall, Wi-Fi syncing is mostly what we expected—a slower version of USB syncing. However, if you're syncing a small amount of media, it doesn't make a huge difference, and if you're syncing apps, there's almost no reason to plug in at all. Also keep in mind that we were using a wireless G network, and if you're on the newer wireless N standard, you might notice even faster Wi-Fi times. And with the ability to keep using your device while you sync, it is very freeing to have Wi-Fi sync around, as long as you don't have anywhere to be. Have you tried Wi-Fi sync on iOS 5 yet? Share your thoughts with us in the comments.

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If you're syncing over Wifi it will all depend on what else is going on in your network. If it's dead of night and all the other computers are asleep it'll probably be wifi. Some other times it'll be USB. Keep in mind that there's no more syncing screen on USB syncs so you can still do whatever you want while the device is syncing.

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Even when the devices have a dedicated WiFi network, USB will still be faster. Look at bmike's accepted answer; he's got it right. –  CajunLuke Sep 4 '12 at 15:36

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