Indeed, you'd be amazed how quickly your iPhone (or your LTE-enabled iPad, for that matter) can gobble up mobile data--particularly if you're, say, watching HD-quality Netflix videos, streaming iTunes Match songs, using your iPhone's personal hotspot with your laptop, or letting iOS update your apps automatically.
Read on for 7 ways to put a lid on your iPhone's cellular data use, starting with...
Stop automatic downloads from using cellular data
With the right settings enabled, iOS will automatically download any new music, apps, or iBooks purchased by any of your iCloud-connected devices. Even better, your iPhone can automatically download and install updates for all your iOS apps.
While certainly convenient, "automatic downloads" can put a serious dent in your monthly cellular data allowance, especially if you have a lot of iOS apps installed.
Luckily, you can flip a switch to block cellular access to automatic downloads, and doing also turns off the spigot for two other data-hogging features: iTunes Radio and iTunes Match.
Just tap Settings, iTunes & App Store, then flip off the "Use Cellular Data" switch.
The only downside is that you can't pick a choose which automatic download features can use cellular data; instead, it's an all-or-nothing deal. In other words, if you don't let your iPhone downloading app updates over cellular, you won't be able to stream iTunes Match tracks on your mobile network, either.
Keep FaceTime calls short and sweet
FaceTime makes for a great way to keep in touch with far-flung family and friends, as well as a surprisingly easy way to drain your monthly cellular data allowance.
You've got a couple of options when it comes to limiting FaceTime's cellular use: either exercise a little self-discipline when it comes to non-Wi-Fi video calls, or shut off FaceTime's cellular access completely.
If you picked option number two, tap Settings, Cellular, scroll down to the FaceTime setting (under the "Use cellular data for" heading), then flick the "off" switch.
Bonus tip: You can turn off cellular access for any of your apps from the Cellular settings screen, not just FaceTime.
Easy does it with Netflix and YouTube
Whether you're stuck at an airport or cooling your heels in a hotel room, watching a movie on Netflix over your iPhone's speedy LTE connection can be a tempting diversion.
But think twice before binge-watching an entire season of House of Cards over LTE. Netflix (or another video-streaming service, for that matter) can easily chomp a gig or more of data an hour for HD-quality video. Indeed, a couple of HD Netflix movies could blow through an entire month of cellular data.
So take it easy when it comes to streaming Netflix, YouTube, or other videos over cellular. Remember, even just a few minutes each day can add up.
If you simply can't live without Netflix while you're on the road, try dialing down your Netflix video quality to save bandwidth. Open your Netflix account in a desktop browser, visit the Your Account screen, click the "Playback Settings" screen, then pick an option: Low (think sub-DVD quality, but only a third of a gigabyte of data use per hour), Medium (0.7 GB an hour for SD-quality video), or High (3GB an hour or more for HD-plus quality).
Turn off auto-playing videos on Facebook
A recent update of Facebook's iOS app added an eye-popping new feature: auto-play videos, which start playing automatically as you scroll through your news feed.
It's a nifty feature, and the default "smart auto-play" setting supposedly adjusts your auto-play video quality depending on your battery life and whether you're on a cellular network. Still, all those auto-playing videos can add up when it comes to cellular data.
If you'd rather turn off auto-play Facebook videos, try this: Open the Facebook app on your iPhone, tap the More button in the bottom-right corner of the screen, scroll down and tap Account Settings, then tap Videos, Auto-play. Flick off the "Smart Auto-play" switch, then pick a new setting--ideally, either "Use Wi-Fi Only" or "Never Play Videos Automatically."
Use a browser with a mobile-friendly mode
A little casual web browsing over your iPhone's LTE connection probably won't drain your monthly data allowance on its own. Again, though, it all adds up.
That's why frugal iPhone users would be well served with a bandwidth-conscious mobile browser--specifically, one that "crunches" webpages into smaller chunks that consume less cellular data.
Among the options: Opera Mini, a free browser that shaves hefty chunks of data from webpages, and Google Chrome, which crunches webpages with its Google-hosted "Data Saver" feature (tap the menu button in the top corner of the screen, then tap Settings, Bandwidth, Data Saver).
Set your podcatcher to only use Wi-Fi
Not that long ago, my wife and I had a brief but annoying cable Internet outage at our house, meaning (horror of horrors!) we had to rough it with LTE for a few days. Oh well, I thought; we're grownups, and we can live without Netflix for 48 hours, right (Um, right)
So imagine my surprise when a rare text alert from my carrier landed on my phone a day or so later: somehow, we'd used more than 90 percent of our cellular data for the month. What happened
Well, turns out the podcast apps on our iPhones hadn't gotten the memo about being careful with bandwidth, and they dutifully downloaded a fistful of new podcasts--yes, including several lengthy video episodes. Oops.
Moral of the story: Make sure your podcast manager of choice only downloads new podcasts over Wi-Fi, not cellular.
For the iOS Podcasts app, tap Settings, scroll down to Podcasts, then flip on the "Only Download on Wi-Fi" setting.
Don't see a similar setting for your favorite podcast app You can always block its cellular access. Tap Settings, Cellular, find your podcast app in the big list of apps, and flip off its cellular switch.
Careful when using Personal Hotspot
Turning your iPhone into a portable hotspot makes for a great way to keep your laptop connected while you're on the go--and it's also a recipe for a jumbo-sized wireless bill.
Unless you tell your desktop or notebook PC otherwise, it'll assume it's using a no-limit Internet connection, leaving it free to download massive system and app updates, grab file attachments from your email provider, sync your Dropbox and Google Drive folders, and perform any number of data-hogging activities.
The good news is that newer iMacs and MacBooks will automatically cool it when it comes to giant system updates over your iPhone's mobile hotspot. Similarly, if you're using Windows 8 or better, you can designate your Personal Hotspot as a "metered connection"; just open the Settings panel on the right side of the screen, click the Network icon, right-click the name of your mobile hotspot and select "Set as metered connection."
That said, even the "metered connection" flag won't stop your laptop from syncing, say, those massive video files in your Dropbox, or pinging Outlook for new messages and attachments every five minutes.
Make sure to pause any file-syncing apps on your desktop before you connect using your iOS Personal Hotspot, and consider using a web client for checking email. Users of iTunes on the desktop should look out for automatic podcast, music, and video downloads. And yes--previous warnings about Neflix, YouTube, and other video-streaming services still apply.
You can use the Activity Monitor app on your Mac to keep an eye on your data usage--just make sure the Network tab is selected. On a Windows 8 or better PC, you can check watch your bandwidth by right-clicking your data connection and selecting "Show estimated data usage."