Why Is My Phone So Slow? How to Find the Cause and Speed It Up

Your phone is slow for one of five reasons. The connection is bad, the storage is full, one app is misbehaving, the software is out of date, or the battery is worn out. Almost every tip online is a fix for one of those five, thrown at you in random order.

Do it the other way. Run a short test that tells you which one you have, then fix that one thing. It takes about ten minutes and you do not need to install anything.

The Short Answer

Only slow online? It is the network, not the phone. Test it with Wi-Fi and data off.
Storage almost full? Clear it first. Google says Android problems can start below 10 percent free.
Fast in safe mode? One of your apps is the cause. Remove recent ones one at a time.
Old iPhone, slow and dying fast? Check Battery Health. A worn battery can slow it down on purpose.
None of the above? Update the system and your apps, then restart.

Step 1. Rule Out the Connection

This is the one most people skip, and it is often the whole answer. If web pages, social apps and video are slow but the camera, settings and calculator are quick, your phone is fine. The signal is not.

Turn on Airplane Mode and open something that works offline, like the camera or your photos. If it opens fast, turn Wi-Fi back on and test again. Then try mobile data alone. Whichever one is slow is your problem. Google's own guide for a slow Android puts the connection check first, and says to contact your carrier or internet provider if it keeps up.

If home Wi-Fi is the weak spot, our guide on how to fix slow home Wi-Fi walks through the router side.

Step 2. Restart the Right Way

A restart clears stuck processes, and it is free. Do it before you change anything else.

iPhone. Turn it off from Settings, General, Shut Down, wait a few seconds, then turn it back on.
Pixel and most Android phones. Google says to hold the power button for about 30 seconds if the phone is stuck. If a Restart option shows up, tap it.
Galaxy. If the phone freezes and the power menu will not come up, Samsung says to hold the Side key and Volume Down together for more than 7 seconds.

If the phone is quick for a few hours after a restart and then slows down again, keep going. Something is building up, and the next steps find it.

Step 3. Check Your Storage

A full phone is a slow phone. The system needs empty space to work, update and cache files. Google says an Android phone can start having problems when less than 10 percent of its storage is free.

iPhone. Go to Settings, then General, then iPhone Storage. Apple shows each app and how much space it uses, plus suggestions at the top. Tap an app to Offload it. Apple says offloading removes the app but keeps its documents and data, so you lose nothing when you reinstall it.
Android. Open Settings and find Storage. Clear big videos, old downloads and apps you never open.
Galaxy. Samsung also has Device care in Settings, with a storage and memory section.

The biggest wins are almost always videos and old message threads full of photos. Clearing a cache helps a little, but deleting one long 4K video helps more. If Safari or Chrome is the slow part, our guide on how to clear the cache on your iPhone covers the browser side.

Step 4. Find the App That Is Doing It

One bad app can drag the whole phone down. Android has a clean way to prove it. Safe mode.

Google says safe mode turns off every app you downloaded, for now. Restart into it using your phone maker's steps. Then use the phone for a few minutes.

Fast in safe mode? An app you installed is the cause. Restart normally, then remove your most recent apps one at a time, checking after each one. Once the lag is gone, you found it. Put back the others.
Still slow in safe mode? Your apps are off the hook. Go to the next step.

iPhones do not have a safe mode, so think about timing. Did the lag start after you installed something? Remove it and see. Also update your apps. Google says to do this from the Play Store under your profile, then Manage apps and devices. On an iPhone, open the App Store and tap your profile.

Step 5. Update the System

Old software can carry bugs that a fix already exists for. Check for updates and install them.

iPhone. Settings, General, Software Update.
Pixel and most Android phones. Google lists Settings, then System, then Software update.
Galaxy. Samsung says to open Settings, then Software update. Newer One UI versions show Check for updates.

One warning. Right after a big update, a phone can feel slow for a day or two while it finishes work in the background. Give it a night on the charger before you judge it.

Step 6. Check the Battery

This is the cause most guides mention last, and on an older iPhone it is often the real one.

Apple says that when a battery ages, it may not be able to deliver the peak power the chip asks for. To stop sudden shutdowns, the iPhone can manage performance. Apple lists the effects as longer app launch times, lower frame rates while scrolling, a dimmer screen and lower speaker volume. On the iPhone 6 through the iPhone XS and XR, Apple says this feature turns on after the phone shuts down without warning. For the iPhone 11 and later, Apple says aging can still bring slower app launches and lower frame rates, though the system manages it in a newer way.

Here is how to check.

iPhone 15 and newer. Settings, then Battery, then Battery Health.
iPhone 11 to 14. Settings, then Battery, then Battery Health and Charging.

Apple says the fix for a worn battery is a new one, which restores full performance. That is usually far cheaper than a new phone. On a Pixel 8a or newer, the same screen lives under Settings, then Battery, then Battery health.

If the phone also feels hot while it lags, deal with the heat first. Our guide on why your phone is so hot explains the safe way to cool it down.

The Advice We Disagree With

Closing all your apps. It feels like it should help. It does not. Apple says you should close an app only when it stops responding, and that closing all your apps does not change how the device performs. Phones pause apps you are not looking at. Opening them again from scratch takes more work, not less.

Cleaner, booster and RAM apps. Many of the pages that rank for this question end by selling one. Skip them. Your phone already has the tools built in. iPhone Storage on an iPhone, Storage and safe mode on Android, Device care on a Galaxy. A booster app is one more thing running in the background.

Factory reset as step one. A reset wipes the phone. Google lists it as the last resort, after everything else, and says to back up first. Even then, if the bad app comes back when you reinstall your apps, the lag comes back too.

When It Is Time to Let Go

Some phones are just old. Each new system update asks more of the chip, and a phone that was quick five years ago can feel heavy on today's apps even with a new battery and clean storage. If you did every step above and it is still slow, look at whether it still gets security updates. Our guide on when to replace your phone helps you decide.

The Bottom Line

Test before you fix. Airplane Mode tells you if it is the network. Storage tells you if it is full. Safe mode tells you if it is an app. Battery Health tells you if it is the battery. Fix the one that fails, restart, and stop there. You do not need a cleaner app, and you do not need to close your apps.

Keep Reading

Phone makers change these menus with almost every update. Follow the latest in our devices news, or browse more plain tech advice.

Questions Readers Ask

Why did my phone suddenly get so laggy?

Look at what changed. A big update can keep the phone busy in the background for a while. A new app can misbehave. Storage can fill up after a long video or a big photo sync. Restart the phone first, then check storage and recent apps. If the lag started with a new app, remove it and see if the lag goes away.

How do I find out what is slowing down my phone?

Go one step at a time. Turn off Wi-Fi and mobile data and open an app that works offline. If it is fast, your connection is the problem. Then check free storage. Then restart in safe mode on Android. If the phone is fast in safe mode, one of your apps is the cause. On an iPhone, check Battery Health too.

How do I clean my phone so it runs faster?

Free up storage, not memory. On an iPhone go to Settings, General, iPhone Storage and offload apps you do not use. On Android check storage in Settings and clear what you do not need. Skip cleaner and booster apps. They add one more app running in the background.

Does closing apps make my phone faster?

No. Apple says to close an app only when it stops responding, and that closing all your apps does not change overall performance. Android works the same way. Phones are built to pause apps you are not using.

Can a virus slow down my phone?

It can, but it is rarely the first cause. Apps from outside the official app stores are the usual way in. If the phone is fast in safe mode on Android, a downloaded app is the problem, so remove recent apps one at a time. Our guide on how to tell if your phone is hacked lists the other signs.

Do phones slow down on purpose?

Some do when the battery is worn. Apple says iPhones can manage performance when an aged battery cannot deliver peak power, which can mean slower app launches and lower frame rates. A new battery fixes it. Software updates on very old phones can also feel slower, because new features ask more of old chips.