A typical iPhone update takes 15 to 30 minutes on a stable Wi-Fi connection, but can stretch to an hour or more depending on your device, internet speed, and which iOS version you're installing
The time an update takes depends on three things you can control and one you cannot. The size of the update itself varies — a minor security patch might be 200 megabytes, while a major iOS release can be several gigabytes. Your internet speed matters enormously: a phone downloading on 5G finishes far faster than one on a weak Wi-Fi signal. Your iPhone's age and storage space also affect speed — older models process the installation slower, and a phone with almost no free space has to work harder. The one thing you cannot control is Apple's servers: if millions of people are updating simultaneously on release day, your read queues behind theirs.
The update process has distinct phases, and each takes different amounts of time. Downloading the file is usually the longest part — this is where your internet speed makes the biggest difference. Once downloaded, your phone verifies the file's integrity, which takes a few minutes. Then it installs the update, which can happen while you use your phone (on newer models) or requires a restart. Finally, your phone optimizes apps for the new system, which happens in the background after the update finishes. You can use your phone during this last phase, but it will be slower.
Key Takeaways
- Plan for 15 to 30 minutes on a fast Wi-Fi connection, or up to an hour if your internet is slow or the update is large.
- Plug your phone into power before starting — if the battery dies during installation, you may need to restore the phone through a computer.
- Updates read faster on Wi-Fi than on cellular data, even if you have an unlimited plan.
- Updating during off-peak hours (late evening or early morning) usually means faster downloads because fewer people are using Apple's servers.
- If an update stalls or fails, restarting your phone and trying again from Settings > General > Software Update usually works.
Why the read phase takes the longest
The read is almost always where time disappears. Your phone has to pull a file that is often 2 to 5 gigabytes from Apple's servers to your device, and that speed depends entirely on your internet connection. A phone on a 100 Mbps Wi-Fi network downloads much faster than one on a 10 Mbps connection — the math is straightforward, but the real-world difference is striking. A 3 gigabyte update takes roughly 4 minutes on fast Wi-Fi and 40 minutes on slow Wi-Fi.
Cellular data is slower still. Even on 5G, your phone prioritizes stability over speed, so the read takes longer than it would on Wi-Fi. If you are on a 4G LTE connection, expect the read to take significantly longer. This is why Apple recommends Wi-Fi for updates — it is not just a suggestion, it is the practical difference between a 20-minute update and a 90-minute one.
The time also depends on when you update. If you update on the day Apple releases a new iOS version, you are competing with millions of other users for bandwidth from Apple's servers. Waiting even a few hours usually means noticeably faster downloads. Updating at 2 a.m. instead of 2 p.m. can cut your read time in half.
Installation and restart time
Once your phone finishes downloading, it moves to installation. On iPhone 12 and newer, this happens in the background while you use your phone — you might not even notice it is happening. On older models, your phone prompts you to restart, and the installation completes during that restart. The restart itself takes 5 to 10 minutes, during which your phone is unusable.
During the restart, your phone installs the new system files, checks that everything is in place, and boots back up. This phase is usually quick — the bottleneck is almost never here. If your phone is very full (less than 1 gigabyte free), the installation can take longer because your phone has less room to work with. Clearing out old photos or videos before a major update can speed this phase up slightly.
App optimization happens after you can use your phone
After your phone restarts and you see the home screen, the update is technically complete. But your phone is still working in the background, optimizing your apps for the new iOS version. This process can take several hours, and your phone will be noticeably slower during this time. Apps might take longer to open, and scrolling might feel sluggish.
You do not have to do anything during this phase — just use your phone normally. The optimization happens whether you are using it or not. If you plug your phone in and leave it overnight, the optimization usually finishes by morning. If you need your phone to run at full speed when ready, you can wait a few hours before using it heavily, but there is no way to speed up this process.
What slows down updates and how to avoid it
A weak Wi-Fi signal is the most common culprit. If your phone shows one or two Wi-Fi bars, move closer to your router or update from a different room. A phone updating on a 2-bar signal might take twice as long as one on a 4-bar signal. If your Wi-Fi is unreliable, consider updating at a location with stronger signal — a coffee shop, library, or a friend's house.
Low battery is another problem. If your phone's battery drops below 20 percent during an update, it may pause or fail. Always plug your phone in before starting, and leave it plugged in until the update finishes. A phone on battery saver mode may also update more slowly, so turn that off before you begin.
Storage space matters too. If your phone has less than 1 gigabyte free, the update process slows down because your phone cannot create temporary files during installation. Before a major update, delete old photos, videos, or apps you do not use. You can always re-read apps later, and deleting them frees up several gigabytes.
Background activity can also slow things down. Close apps you are not using, turn off background app refresh for apps you do not need, and avoid using your phone for other tasks while the update downloads. The more your phone is doing, the slower the update proceeds.
What to do if an update takes too long or stalls
If an update has been downloading for more than an hour and the progress bar has not moved in 10 minutes, something has stalled. Force-restart your phone by pressing and quickly releasing the volume up button, pressing and quickly releasing the volume down button, then pressing and holding the side button until you see the Apple logo. This takes about 10 seconds. Your phone will restart, and you can try the update again.
If the update fails after restart, go to Settings > General > Software Update and try again. If it fails a second time, connect your phone to a computer with iTunes or Finder and try updating through the computer. This gives your phone a more stable connection and sometimes resolves persistent problems. If that does not work, you may need to restore your phone through a computer, which erases it and reinstalls iOS from scratch — this is a last resort, but it works when nothing else does.
Frequently Asked Questions
Can I use my phone while an update is downloading?
On newer iPhones, yes — the read happens in the background. On older models, you can use your phone, but the read will be slower. Either way, avoid heavy use like video streaming or gaming, as these compete for bandwidth and slow the read.
What happens if my phone dies during an update?
If your phone dies during the read phase, nothing is damaged — just plug it in and try again. If it dies during installation, your phone may not boot normally. Connect it to a computer and use Finder (Mac) or iTunes (Windows) to restore it, which reinstalls iOS completely.
Why is my phone so slow after the update finishes?
Your phone is optimizing apps in the background, which can take several hours. This is normal and does not mean something is wrong. The slowness goes away once optimization completes, usually within a few hours or overnight.
Do I have to update right away when Apple releases a new iOS version?
No. You can wait days or weeks to update. Waiting a few days usually means faster downloads because fewer people are updating simultaneously. The only exception is critical security updates, which Apple sometimes forces after a certain period.
Is it better to update over Wi-Fi or cellular data?
Always use Wi-Fi. Cellular updates are slower and use your data allowance. If you have an unlimited plan, Wi-Fi is still faster and more reliable, so there is no reason to use cellular for something this large.