Why force quitting apps to save battery life is a terrible idea

By , Oct 9, 2015

Force quit app

I’m standing in line at the coffee shop. A man in front of me is frantically swiping up on all the cards in the App Switcher to force quit the applications he just launched a minute ago. I know why he’s doing this, but I can’t help asking him about it. “I’m doing this to save battery,” he answers, not knowing what he just did has the exact opposite effect on his iPhone’s battery life.

Telling him he’s wrong and explaining why force quitting apps drains his battery faster than leaving them in the App Switcher is a lost cause. I know it’s a lost cause because I have been telling people the same thing for years. No one, including members of my own family, can break this bad habit and trust the operating system will manage their apps in a way that will actually save battery life.

If you are someone who force quits apps believing your battery will last longer, then stop what you are doing and read this.

Long story short

For those of you who don’t care about the specifics, here is the gist of the story:

  • Unless an app is not behaving as it should, you should never force quit an app
  • Unlike what many people believe, force quitting an app actually wastes battery
  • Apple is giving developers proper tools to have their apps work efficiently in the background
  • Users should trust the system is effectively managing apps that aren’t active

Now if you want to geek out about the topic of force quitting apps, read on for a detailed explanation.

Terminology: closing vs force quitting

For the sake of clarity, let’s make sure we are on the same page about basic terminology.

Closing an app is done by pressing the Home button.

Force quitting an app requires the user to double press the Home button, then swipe up on the app card in the App Switcher.

The myth

The myth is of course that force quitting applications by removing them from the App Switcher will save battery because these apps won’t be running in the background any longer. That is what people believe, and in many cases, that’s what they have been told by friends, family, or even worse, by Apple employees.

The reality

The reality is that once you close an application by pressing the Home button, it stops using CPU and the app memory usage is suspended. At that time, the app is not actively running in the background.

There are exceptions, which we’ll learn about, but as a general concept, pressing the Home button freezes the app, putting it in a suspended state that uses virtually no battery. By keeping an app in memory, the system makes sure you can pick it up where you left off when you launch that app again.

When you force quit an app, it offloads the memory used by this app, which of course has a negative impact, albeit very small, on your battery. Next time you launch this app, the operating system will run processes to load it back in memory, using yet more battery. By force quitting the app and launching it again soon after, you actually drained your battery twice, for no reason, since it was not consuming any power to begin with.

The take away is that once you press the Home button, the app is in a suspended state using no CPU, and although it is still in memory, this has virtually zero effect on battery.

Again, there are exceptions to this general rule of thumb, and we will discuss them later.

Think about it this way

On the last episode of our podcast Let’s Talk Jailbreak, I made an analogy which I was told by several listeners made lots of sense, so I figured I would explain it here in details.

Let’s imagine you are watching TV and you’re thirsty. You go to the kitchen, grab a glass, fill it up with water, and drink half of it. You then empty the other half of the glass in the sink, and go back to the couch.

Five minutes later, you are thirsty again. You go back to the kitchen, fill up the glass again, drink half of it again, and throw the other half in the sink.

It doesn’t make sense, right? Why would you throw that water away when you’re very likely to be thirsty again in the near future? Why wouldn’t you leave that half full glass on the counter and drink from it when needed instead of filling it up again?

You are wasting resources, and that is exactly what you are doing when you force quit an app. You are wasting battery by taking the app out of memory, and loading it back once you launch the app again.

How iOS handles things when you close an app

In a post detailing misconceptions about iOS and multitasking, Fraser Spears explains that apps can be in one of five states of execution:

  • Not running: the app has not been launched or it’s been terminated. It’s not resident in memory. It is not using battery.
  • Inactive: the app is in the foreground but not being used, such as when you lock your device while an app is currently on screen. It is resident in memory, but uses no CPU or battery.
  • Active: the app is currently being used. It uses CPU and is resident in memory. It uses battery.
  • Background: the app is still processing code, but it is no longer on screen. It uses CPU and is resident in memory. It uses battery.
  • Suspended: the app is no longer on screen or executing code. It is not using CPU but it is resident in memory. It is not using battery.

From active to background, to suspended

If you are currently using an app, it is considered to be active. It’s using CPU and memory. As soon as you press the Home button, the app is moved to the background where it will stay for a very short period of time (a few seconds) before being suspended. Within seconds after you pressed the Home button, the suspended app is no longer using CPU but it is still resident in memory, so that it can resume faster when you next open it.

From suspended to not running

If you are launching a memory-intensive game, for instance, and your device needs memory, the system may purge suspended apps to make more space for the foreground app. Purging the suspended app will put it in the “not running” state and it will then be completely removed from memory. Simply explained, it is the equivalent of iOS automatically force quitting an app on your behalf to free up memory for other apps.

You can read more about execution states for apps in Apple’s app programming guide for iOS.

Exceptions to the rule

It is time to talk about exceptions to the rules I just mentioned. In its developer library, Apple goes in great details about these types of apps, which I will briefly sum up here.

Apps that need to finish executing a short task: these are apps that have initiated a process in the foreground but are offered a time extension to finish that process once the app is closed. For example, if you are using a third-party email client to send a very large file, you may tap “Send” and close the app. This app can request an extension to be backgrounded while it completes the task. Once the task is done, the app will be suspended.

Apps that need to download content in the background: these are apps that initiate downloads in the foreground but need time to finish that task when the app is moved to the background. According to Apple, these apps can hand off management of those downloads to the system, allowing the app to be suspended or terminated while the download continues. A good example would be a podcast application downloading a new episode. You can initiate the download, close the app, but the download will be processed in the background.

Apps that need to execute long-running tasks: these are apps that must be allowed to run in the background to perform specific types of tasks, such as playing audible content (a music app), recording audio, actively keeping track of location (a navigation app), supporting Voice over Internet Protocol (Such as Skype), processing new content regularly (magazine-style apps), and receiving regular updates from external accessories (an app linked to a physical heart rate monitor).

Once again, the user must trust that the system will efficiently manage these apps.

You can read more about background execution in Apple’s app programming guide for iOS.

About Background App Refresh

With all that said, some of you are probably wondering what happens to applications for which Background App Refresh is enabled. I couldn’t find much technical details about this feature, except for this support document:

After you switch to a different app, some apps run for a short period of time before they’re set to a suspended state. Apps that are in a suspended state aren’t actively in use, open, or taking up system resources. With Background App Refresh, suspended apps can check for updates and new content.

As it turns out, an earlier version of this same document gave much more details about how Background App Refresh actually works:

Some apps can continue to run in the background. You can allow these apps to refresh themselves by turning on Background App Refresh. This settings lets apps check for new content and download updates, or retrieve updated content in the background when they receive push notifications.

To save battery, apps running in the background refresh at certain times, like when your device is connected to Wi-Fi, plugged into a power source, or being actively used. iOS learns patterns based on how you use your device and tries to predict when an app running in the background should refresh. It also learns when the device is typically inactive, like at night, to help keep apps from refreshing when you’re not using your device. Apps can also schedule background refreshing based on your location.

Based on that earlier version of the support document, and also based on common sense, it’s safe to assume that iOS is smart about the way it refreshes apps in the background, and won’t recklessly update apps all day long. For example, it won’t continually refresh your Facebook feed in the background throughout the day.

If you’re conscious about battery life, it’s probably a good idea to venture into Settings > General > Background App Refresh, and disable apps you don’t use or care enough to let them update in the background. Personally, I turned off Background App Refresh for about 80% of my apps. I just don’t care enough about these being updated to let them run without me manually launching them.

Also see: ways to save battery life on your iPhone

So, when should you force quit apps?

In theory, you should never have to force quit applications. In practice, it’s a little more subjective because there are times where you must force quit an app, such as when it doesn’t function properly, or if it is frozen. In this case, it is of course suggested to force quit applications. For everything else, you should let iOS handle it because that’s its job. Yours is just to enjoy the device.

Now do your friends and family a favor. Next time you see someone force quitting applications, either send them a link to this post, or explain to them what doing that is actually a terrible idea.

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  • kespiritu

    It reduces UI lag, thats why I do it.

  • kickinghorse99

    So simple but turn out so complicated. Try it else go on…

  • The Pool Man

    I don’t understand why Apple doesn’t offer ‘quit all open apps’ at reboot.

    • pegger1

      That doesn’t even make sense. All open apps ARE automatically closed on a reboot.
      You’re confused on the app switcher. It’s not just open apps that appear there, it’s the most recently used apps, even those that are already closed.

  • Adrian

    There is 1 app that you should always force kill otherwise your battery is empty in less than an hour (even without activated background activity): Facebook…
    I once let it “idling” in the background and the battery went up to -900mA… (Tweak BatteryLife)

  • Pedro Leite

    I’ve read that explanation a lot of times, and it’s great, except for one thing: none of you seem to have an iPad 2 running on iOS 8 or 9.

    Some of us don’t force quit apps to save battery time, but to make our devices usable. I assume that means saving RAM, and therefore making iOS more stable and fluid. Some savvy may explain otherwise, but I’ll still believe in my daily experience…

    I use my iPad manly to study. Try using Pages on an iPad 2 for a while, closing it (home button), and opening safari. Than close safari and open Pages back. Yep, iOS will slow down and stutter.

    If you force quit safari, though, Pages will run significantly better (though still not perfectly).

    I mention Pages and Safari because those are my most used apps, but the idea applies to any of them: apps suspended or in background make iOS run slower, crippling already crippled old devices.

    That’s definitely one thing to consider.

    Ps. No, I don’t think I should buy a new iPad. I do think Apple should let users of old devices to downgrade, at their will. I strongly believe not letting us do that is a policy used (among other reasons) to improve sales, and that’s just wrong. I love Apple products, but I hate that I can’t use my iPad 2 as I should.

    Ps. I’ve had an iPhone 3G, an iPhone 4S, an iPad 2 and now have an iPhone 6. I’ll probably keep buying Apple products as I can afford them.

  • Razick Rilshad

    I always force closing the background apps.now I learned something thanks

  • Joey Hoey

    I dislike the premise of this article because it blames end users for the badly thought design model used by designers and developers. For users it is normal to equate shutting down an app with preserving memory. Writing a whole article about how “users are idiots” and that they should let Apple’s iOS do it’s job misses the target on what real user experience means. The problem here is Apple who is not designing systems that fit most users’ mental models. Trying to “train” users into interacting with their devices the way Apple intended reinforce the privilege “in the know” mentality versus the bearish and unlearned mass attitude that is responsible for much of the problem with Silicon Valley and how it makes products that regular people can’t use.The problem is with Apple, not users. Apple should create an OS that acts the way most unlearned users expect, as opposed to stigmatizing your own clients for being ‘too stupid to get it.” It’s called good user experience. UX is not about pretty buttons and menus.

  • This is all good, assuming developers are using the APIs correctly. Also, whenever there’s a major iOS update it is quite common place for some apps to behave incorrectly until they are properly updated. Just my 2¢. 🙂

  • Abdul

    Hi guys sorry completely off topic but i just wanted to ask is there an accessory that charges my ipad mini and my iphone 6 at the same time. What i mean is like a dock with two positions for ipad and iphone.

  • Ran Mintz

    Very important information. Thanks.i wonder what about GPS apps (like waze), should I force quit once I’m done using it?

  • AI

    Wait, so you’re saying never force quit apps and keep every app you use open in the background?
    Ok, I buy the battery thing. It makes sense. But what about the RAM usage? Doesn’t that slow down your phone?
    Oh, and what’s the point of the app switcher if you have to scroll and scroll if you want to quickly switch between apps (and i’m assuming you use more than 5 apps..)?

  • bradmacpro

    quitting the apps will free up memory, so there is a reason to do this, just not for saving battery. In fact relaunching an app will use more battery life.

  • yzjustdatguy

    This doesn’t apply to snapchat lol. Please force quit that app when not in use

  • James

    What about when you just don’t want all those apps in the app switcher? It can be a little hard to find the app you want if there are a bunch of apps left open.

  • Anton Prakapenkau

    Is it ok writing like this “cause because” at the beginning of the article?

    • pegger1

      Why wouldn’t it be OK? “Cause” in this usage isn’t the incorrect shortened version of because. It’s a noun.

      ” I know it’s a lost cause because I have been telling people the same thing for years.”

      -cause (noun)
      a principle, ideal, goal, or movement to which a person or
      group is dedicated:
      the Socialist cause; the human rights cause.

  • Wilbert

    so I been using the smartclose tweak I’m wondering does that make any good in battery life ?

  • Ian

    Unfortunately iOS doesn’t handle memory perfectly. My example is playing Crossy Road (not a particularly demanding game) on my iPad Air. Often it lags. Force quitting apps in multitasking then relaunching fixes the lag. It seems iOS frees enough memory to launch the game but not necessarily enough to play it smoothly. This I have to achieve manually.

  • Nolan I.

    You missed one critical detail – people with older devices.

    Let’s go back to that water cup analogy:
    iPad Pro users (once it comes out) will have a gigantic five gallon bucket of water. iPhone 6+ users have a pretty big pitcher of water. iPhone 5-6 users have a normal old water cup. Last of all though, iPhone 4s users have a tiny little shot glass.

    Suspended apps don’t take up CPU or battery life, but they take up MEMORY! This is a precious commodity for older devices like the 4s, iPad 2, and iPhone 4s.

    The water in the cup is apps, and the cup is memory. Some apps take up MUCH more “water”, and once it starts to get to the top things start to slow down. Once it overflows, the app will crash.

    I have an iPod 5 and if I don’t quit my apps, some don’t even open. For example I normally have to respring my iPod or go to safe mode to open Smashy Road. And even then, it is a 50/50 chance of whether it will open.

    So there is my take on quitting apps – please consider it.

  • M_Hawke

    Oh, here’s one app that I ALWAYS force close to save battery: Waze. Because it IS a battery hog and force closing it does save my battery significantly.

  • Giovanni Cardona

    That’s cool and all… but try to explain that to people with OCD

  • Kong Fury

    First I recommend googling “iOS app lifecycle” for a more accurate account of the true life cycle of an iOS app. There you will find a link on the Apple developer site which goes through the execution states of an iOS application. In this particular case I believe we are referencing an app in the “Suspended” state where it clearly states the app consumes memory. In my opinion there is more than one reason to “force quit” an app than battery life. Although I would not use the term “force quit” because there is a notification sent to the app so that it is allowed to close gracefully. This is not the same as sending a kill signal as with linux or other operating systems. The terminology force quit here implies something that is not completely accurate. Force quit is often (but not always) used to kill an application or process that is hung or otherwise not responding. Having apps open that you are no longer using needlessly consumes memory. Indeed iOS will release memory as stated on the developer site in extreme low memory conditions, or pop the low memory warning.

    Leaving apps open is not that much unlike leaving apps open in OS X. They may not be draining battery life, or they could be if configured to perform background operations, but they are still using resources. Also, I believe the blanket statement of “doing it wrong” is itself incorrect. Because there is an assumption made that people do not have background refresh set or location services on for background apps. Likewise network com is battery intensive even if refreshes are happening every so often. Lots of apps open with each performing minimal refreshes over time equals a lot of refreshing especially when location services are being used. So I don’t know that the blanket statement of this article title is true because it assumes you have everything set to not use background location services or background refresh which i would assume most people do not have configured in this manner.

    It would be like me saying I am the richest man as an article title… then toward the middle of the article saying “in my house”. It is more misleading than it is true or helpful. Just my opinion.

  • BrS

    You’re just plain wrong. I have particular applications that run my battery down even when they’re not open. Killing them saves my battery.

  • The jailbreak tweak Dissident has a feature where swiping apps up out of the app switcher instantly puts them in deep freeze instead of force closing them. Great for those with an OCD about having an empty switcher.

  • Luna

    I force quit apps because sometimes leaving them in the background makes my phone much slower? It seems to solve the problem so there’s that

  • Cascadia R

    Great article!
    Thought though: Except maybe when you are out of RAM… for example attempting to look at CADD/BIM building designs in BIM 360 Glue, if the file is large the app will warn that you are running out of memory and to try closing background apps. Using a system monitor I could see the RAM usage drop by more than half after swiping away all the cards in the app switcher.
    There may be more to the story here but seems maybe another special case scenario.

  • ckrachmer

    this does not apply to the sonos app…that thing engages in so much background activity, it drains the hell out of your battery if you don’t quit it. not sure, but i’m guessing that’s true of other apps out there…usually, when people make blanket, “youre doing it wrong” statements, they’re only partially right.

  • Rombout

    I find this a bit hard to be leave, how does a app than actually work in the background. In this theory that would not be possible thus. Eventually you will have each and every app “open” on your iphone? It slow down system when i got to much

  • eilfurz

    i never thought about saving battery life, but about having more ram available. on my 5s, safari often grays out the dictation-symbol. force quitting apps in the app switcher remedies this.