iOS updates usually take 15 minutes to an hour on your device, but the full process — from when Apple releases it to when your phone finishes installing — can stretch across several days

The time you spend watching your phone update is different from the time between when Apple announces an update and when you can actually use it. Apple releases iOS updates to everyone at once, but your phone may not read it when ready. Once your phone starts installing, the actual process on your device typically takes 15 to 60 minutes, depending on your model, how much storage you have free, and whether you're updating from a very old version.

The confusion usually comes from three separate timelines: when Apple releases the update (usually a Tuesday morning), when your phone downloads it (which can be hours or days later), and when the installation finishes on your device (which is the part you watch). Understanding which one matters for your security means knowing what you're actually waiting for.

Key Takeaways

  • The installation on your phone — the part where you see the progress bar — usually takes 15 to 60 minutes depending on your device model and how much free storage you have.
  • Your phone may not read the update when ready after Apple releases it, especially if you have automatic updates turned off or if Apple is rolling it out gradually.
  • Older iPhone models and phones with less than 5 GB of free storage typically take longer to update than newer models with more space available.
  • Plugging in your phone and connecting to Wi-Fi before starting the update can reduce the time it takes, since cellular downloads are slower and battery drain can pause the process.
  • If your update stalls or gets stuck, force-restarting your phone and trying again usually works better than waiting or trying over cellular.

Why your phone might not update right away

Apple releases iOS updates to all devices at the same moment, but your phone does not automatically read it within minutes. If you have automatic updates turned on in Settings > General > Software Update, your phone will read the update overnight when plugged in and on Wi-Fi — but this can happen the night of the release or several nights later, depending on your phone's schedule and whether the conditions are met.

Apple also sometimes rolls out updates in stages, meaning not every phone gets the read available at the exact same time. This is less common with major releases (like iOS 18) and more common with smaller security updates. If you want to update when ready rather than wait for your phone to do it automatically, you can go to Settings > General > Software Update and tap "read and Install" manually.

Network congestion also matters. If millions of people are downloading the update at the same time, your read may be slower. This is why updates released on a Tuesday morning can take longer to read on Tuesday afternoon than on Wednesday morning.

How long the actual installation takes on your device

Once your phone starts installing — the part where you see "Preparing Update," then a progress bar, then "Installing" — the process usually takes 15 to 45 minutes on newer iPhones (iPhone 12 and later) and 30 to 60 minutes on older models. During this time, your phone will restart multiple times. You will see the Apple logo, a progress bar, and possibly a "slide to upgrade" screen. Do not force-restart your phone or unplug it during this time.

The installation is slower on older models because they have slower processors and less RAM. An iPhone 8 or iPhone XR will take noticeably longer than an iPhone 15. If your phone has less than 5 GB of free storage, the installation can take significantly longer because iOS needs temporary space to unpack and verify the update files before installing them.

If you are updating from a version that is several releases old — for example, jumping from iOS 16 to iOS 18 — the installation will take longer because your phone has to explore multiple updates' worth of changes. Updating from iOS 17 to iOS 18 is faster than updating from iOS 15 to iOS 18.

What slows down updates and what speeds them up

Your phone's battery level matters more than many people realize. If your battery is below 20%, your phone may pause the update or refuse to start it. Plugging in your phone before you start the update and keeping it plugged in throughout the process is the single most reliable way to avoid delays.

Wi-Fi connection is faster and more stable than cellular. If you start an update over cellular and your signal drops, the read may pause or restart. Connecting to a reliable Wi-Fi network before you begin saves time and reduces the chance of the update getting stuck.

Background apps and processes can slow down the installation. Closing apps before you update, or straightforward letting your phone sit idle during the installation, helps it move faster. Restarting your phone before you start the update also clears out temporary files and can speed up the process slightly.

When updates get stuck and what to do

If your phone has been "Installing" for more than 90 minutes, or if the progress bar has not moved in 30 minutes, the update is likely stuck. The most common causes are low battery, poor Wi-Fi connection, or insufficient storage space.

The first step is to force-restart your phone. The method depends on your model: on iPhone 8 and later, quickly press and release the Volume Up button, quickly press and release the Volume Down button, then press and hold the Side button until you see "slide to power off," then release and wait for the phone to restart. On older models, press and hold the Top (or Side) button and the Volume Down button together until the restart screen appears.

After the restart, your phone will usually resume the update from where it left off. If it gets stuck again, try connecting to a different Wi-Fi network, or plug in your phone and wait 30 minutes before trying again. If the update fails multiple times, you may need to use a computer and iTunes or Finder to restore your phone, but this is rare.

Security updates versus major releases

iOS security updates (like iOS 17.5.1) are smaller and install faster — usually 5 to 15 minutes — because they contain only security patches and bug fixes. Major releases (like iOS 18) include new features and larger changes, so they take longer to read and install.

Security updates are released more frequently and are important for closing vulnerabilities that could affect your data or privacy. Major releases come once a year, usually in September. Both types of updates are worth installing promptly, but security updates are the ones that directly protect you from known threats.

What to expect after the update finishes

After your phone restarts and shows your lock screen, the update is technically complete, but your phone may still be doing background work for several minutes. Apps may take longer to open, and your phone may feel slightly slower for a few minutes as it indexes files and rebuilds caches. This is normal and does not mean something went wrong.

You can use your phone when ready after the update finishes, but if you notice it is running slowly, restarting it again can help. Some people also notice that their battery drains faster for a day or two after an update — this is usually because the phone is doing background processing, not because the update itself is faulty.

Frequently Asked Questions

Can I use my phone while it is updating?

No. Once the installation starts (the part with the progress bar), your phone will restart and you will not be able to use it. The read phase before installation starts is different — you can use your phone while it is downloading, though it may be slower. Once you tap "Install Now," set your phone down and leave it plugged in.

What if I turn off my phone during an update?

If you force-restart your phone during the installation phase, it will usually resume the update when it turns back on. However, if you turn it off during the read phase, you will need to start the read again. Avoid turning off your phone during updates if possible — let it finish, even if it takes longer than expected.

Why does my iPhone 8 take so much longer to update than my friend's iPhone 15?

Older phones have slower processors and less RAM, so they take longer to unpack, verify, and install update files. An iPhone 8 updating to iOS 18 may take 60 minutes or more, while an iPhone 15 might finish in 20 minutes. This is normal and does not indicate a problem with your phone.

Is it safe to update over cellular instead of Wi-Fi?

It is technically possible, but Wi-Fi is more reliable. Cellular connections can drop, which may pause or restart your read. If you must update over cellular, make sure you have a strong signal and plenty of battery. Wi-Fi is the safer choice.

Should I update when ready when Apple releases it, or can I wait?

Security updates are worth installing within a few days of release, since they close known vulnerabilities. Major releases can wait a week or two if you prefer, though there is no harm in updating when ready. Avoid waiting more than a month, since older versions stop receiving security patches.