Wi-Fi Assist is an iPhone setting that uses cellular data when your Wi-Fi connection is weak or slow, so pages, maps and video calls keep working. On iOS 26 and earlier, you find it at the bottom of Settings > Cellular (or Mobile Data). Since iOS 27, Apple has replaced it with Connectivity Assist, which sits in Settings > Wi-Fi. It can use more of your data plan, so turn it off if your data is limited, for example on a small travel eSIM plan. This guide shows where the setting is on your iPhone, how much data it uses and when to switch it off.
What is Wi-Fi Assist on iPhone?
Wi-Fi Assist arrived with iOS 9 in 2015. When the Wi-Fi you're connected to is too weak or slow to load what you're doing, your iPhone uses cellular data for it instead. You stay connected to the Wi-Fi network while it happens.
Think of moments like these:
- You walk into the garden or down to the car, and your home Wi-Fi gets weak.
- You're on a busy café, airport or hotel network that is connected but barely works.
- The Wi-Fi works, but it isn't actually connected to the internet.
Without the feature, your iPhone keeps trying on the bad Wi-Fi. With it, the page loads over cellular data. That data comes off your plan, just like any other cellular data.
Wi-Fi Assist is now Connectivity Assist (iOS 27)
In iOS 27, Apple renamed and moved the feature. Apple says Connectivity Assist "replaces and supersedes Wi-Fi Assist, previously found in Cellular settings" (Apple: About Connectivity Assist). It does the same job: it uses cellular data along with Wi-Fi when Wi-Fi is weak, busy or not connected to the internet. The iOS 27 release notes describe it as "more seamless transitions between Wi-Fi and cellular networks" (Apple: About iOS 27 Updates).
Your old choice carries over. If Wi-Fi Assist was on when you updated, Connectivity Assist is on. If it was off, Connectivity Assist stays off until you turn it on.
Where is Wi-Fi Assist on iPhone?
Where you find the setting depends on your iOS version. To check yours, go to Settings > General > About and look at iOS Version.
iOS 27 and later: Connectivity Assist
- Open Settings and tap Wi-Fi. Make sure Wi-Fi is on.
- Scroll down to Connectivity Assist.
- Turn it on or off.
Right there, your iPhone shows how much cellular data Connectivity Assist has used. Tap Reset Data Usage to start a new count (Apple: Connect iPhone to the internet).
You can also turn it off for one network only, for example a home network with an ad blocker you always want to use. Tap the info button next to the network in Settings > Wi-Fi and turn off Use Connectivity Assist.
iOS 26 and earlier: Wi-Fi Assist
- Open Settings and tap Cellular (or Mobile Data).
- Scroll all the way down, past the list of apps.
- Turn Wi-Fi Assist on or off. The number under it is the cellular data it has used.
Can't find it in either place? Update your iPhone and check again. If your iPhone is on iOS 27 or later, the old toggle in Cellular settings is gone.
Does Wi-Fi Assist use a lot of data?
It depends on how often your Wi-Fi is bad. Apple says that with the feature on, "you might use more cellular data". On a good home network you may barely notice it. If you spend a lot of time on weak Wi-Fi, it adds up.
Apple also lists when it is not used (Apple: About Connectivity Assist):
- When your iPhone is roaming internationally.
- When Low Data Mode is on for your cellular line.
- With some third-party apps that stream audio and video.
The easiest way to know is to look at the counter. On iOS 27 it's in Settings > Wi-Fi. On iOS 26 and earlier it's under the Wi-Fi Assist toggle in Settings > Cellular. For your full usage, app by app, see our guide on how to check your data usage on iPhone and Apple's page on using cellular data on your iPhone.
Should you turn Wi-Fi Assist on or off?
Wi-Fi Assist is neither good nor bad. It trades a bit of data for a smoother connection. Here's a simple way to decide.
Keep it on if
- You have unlimited data or a large monthly allowance.
- Your home or office Wi-Fi has weak spots and you hate pages that stall.
- You often make video calls or use maps while moving between Wi-Fi and cellular.
Turn it off if
- Your plan has a small data allowance or charges you for going over it.
- You're using a travel eSIM with a set amount of data and want every gigabyte for maps, messages and bookings.
- You always want to stay on a specific Wi-Fi network, for example because of an ad blocker on your router. On iOS 27 you can turn it off for that network only.
- You often join a friend's phone hotspot with a weak signal and would rather wait than use your own data. More on sharing data in does a hotspot cost money and what is tethering.
Wi-Fi Assist when you travel abroad
Abroad, Wi-Fi is often weak: in hotels, cafés, trains and airports. That's exactly when Wi-Fi Assist kicks in, and when data costs the most.
On your home SIM
Apple says the feature isn't used while your iPhone is roaming internationally. That helps, but don't rely on it alone. If you don't have a travel plan with your carrier, turn off Data Roaming for your home line so it can't use data abroad at all. See the correct roaming settings for an eSIM.
On a travel eSIM
A travel eSIM gives you a fixed amount of data for a fixed number of days. Whether your iPhone treats it as roaming depends on the network it uses, so don't count on the roaming rule here. If your data is limited, do this:
- Set the travel eSIM as your data line in Settings > Cellular > Cellular Data. Cellular data, including what Wi-Fi Assist uses, comes from this line.
- Turn off Connectivity Assist (iOS 27) or Wi-Fi Assist (iOS 26 and earlier) if you want weak hotel Wi-Fi to stay Wi-Fi only.
- Or keep it on and turn on Low Data Mode for the travel eSIM: go to Settings > Cellular, tap the travel line and turn on Low Data Mode. Apple says Connectivity Assist isn't used in cellular Low Data Mode, and Low Data Mode also limits background data (Apple: Use Low Data Mode).
- If you also keep your home line on, think about Allow Cellular Data Switching, a different setting that lets your iPhone use cellular data from both lines, depending on coverage. Keep it off if your home line shouldn't use data abroad.
Check the usage counter every few days, and see our tips to reduce data usage abroad.
Planning a trip? A SimOptions data-only eSIM gives you a set amount of data, so you know what you have and can see exactly what Wi-Fi Assist uses from it. You install it before you leave, and it activates when you arrive in a covered country.
Data-only plans for Europe, the USA and Asia · See all Europe eSIMs · Going somewhere else? Find your destination
FAQs
What is Wi-Fi Assist on iPhone?
It's a setting that uses cellular data when your Wi-Fi is weak or slow, so your apps keep working. Since iOS 27 it's called Connectivity Assist.
Where is Wi-Fi Assist on my iPhone?
On iOS 26 and earlier: Settings > Cellular (or Mobile Data), at the very bottom. On iOS 27 and later: Settings > Wi-Fi > Connectivity Assist.
Why can't I find Wi-Fi Assist in Cellular settings?
If your iPhone is on iOS 27 or later, it moved. Look for Connectivity Assist in Settings > Wi-Fi.
Is Wi-Fi Assist on by default?
Wi-Fi Assist was on by default when it launched with iOS 9 (9to5Mac). After the update to iOS 27, Connectivity Assist keeps the setting you had for Wi-Fi Assist.
Is Wi-Fi Assist good or bad?
Neither. It's useful if you have plenty of data. If your data is limited, at home or abroad, turning it off gives you more control.
Does Wi-Fi Assist work while roaming?
Apple says it isn't used when your iPhone is roaming internationally. With a travel eSIM, turn it off or use Low Data Mode if you want to be sure.
Is "Intelligent Wi-Fi" the same thing?
Intelligent Wi-Fi is Samsung's name for a group of Wi-Fi settings on Galaxy phones. One of them, Switch to mobile data, works like Wi-Fi Assist (Samsung: How to optimize network connectivity). On iPhone, the matching setting is Wi-Fi Assist or Connectivity Assist.
Does turning off Wi-Fi Assist turn off Wi-Fi or cellular data?
No. Wi-Fi and cellular data keep working as usual. Your iPhone just stays on the Wi-Fi network, even when it's weak, instead of helping out with cellular data.
