MasaApps360
English
Device Monitor

Can you monitor CPU usage on an iPhone?

Only partly: iOS lets an app measure its own CPU time, never the whole phone's and never another app's. Device Monitor's CPU Monitor card shows that own-process figure once a second, with a 60-second graph, and this page explains what that number is good for and where to look instead.

4 min read · Updated 2026-10-06

Download on the App Store

What the CPU Monitor card reads

It is on the Monitor tab by default. Every second the app asks iOS for each of its own threads, adds up the CPU share of the ones that are not idle, and prints the sum as CPU Usage with one decimal. Next to it is a word: Low under 40 %, Moderate under 70, High under 90, Critical above.

Below that, Live Activity (60s) draws the last 60 readings from 60s ago to Now, then three boxes: MIN, AVG, MAX. Under those, Processor and Model name the chip and the phone.

So if your iPhone feels slow because a game is downloading in the background, this card will not show it. It typically sits around 1% while idle, since Device Monitor itself uses very little CPU.

Worked example: ten seconds on the card

The example below shows the first ten seconds after opening the app: the window starts empty, so these ten readings are all it holds.

CPU Usage readings, one per second
SecondCPU UsageWhat was happening
14.2%opening the app
20.0%idle, all threads asleep
31.3%graph redraw only
40.8%graph redraw only
50.0%idle again
612.6%scrolling the dashboard
79.1%scroll settling
81.0%graph redraw only
90.7%graph redraw only
100.9%graph redraw only
Stat boxes after second 10
BoxShowsHow it is worked out
MIN0.7%lowest reading above zero
AVG3.8%mean of the 8 readings above zero
MAX12.6%highest reading
Plain mean of all 103.1%not shown by the app

That gap matters: AVG skips every second that read exactly zero, so it comes out higher than the true average whenever the app goes fully idle. Read it as the average while busy, not the average over the minute.

The figure is a sum over threads, so on a multi-core chip it could pass 100 % with several busy threads.

Why iOS hides per-app CPU usage

Every App Store app runs in a sandbox. Older iOS versions let an app list the other processes on the phone; Apple closed that in iOS 9, partly because the list of what you run says a lot about you. Since then there is no public way for an app to read system-wide load or another app's CPU, which is why no iPhone task manager in the App Store can show you a per-process list. Any app that claims it does is showing you its own numbers or made-up ones.

When your iPhone CPU usage seems high: what to check

  • Settings > Battery, then scroll to the per-app list. Tap an app to see its screen and background minutes. An app with hours of background activity is the closest thing iOS gives you to a CPU hog list.
  • Thermal State in the Device Info card (free; add it from Edit Dashboard). Normal means the phone is not throttling; Serious or Critical means it is cooling itself and slowing down.
  • RAM Live shows memory Pressure. Skip Clear RAM: iOS frees memory on its own, and the button can push your other apps out so they reload from scratch.
  • Force-quit the app you suspect and watch whether the phone cools down. Crude, but it is the only per-app test you can run without a Mac.

Free vs Pro

The card, its 60-second graph and the stat boxes are free, with banner ads on the Monitor tab. Pro (weekly or yearly subscription) removes ads and adds Extended History (5 min), a 300-point graph of the same own-process figure. It does not add a whole-phone reading, because none exists for apps to read. If what you want is to find which app drains your phone, the Battery screen in Settings answers that better than any monitor app, ours included.

Questions and answers

Is there a task manager on iPhone?
Not in the Windows sense. The app switcher (swipe up and pause) lets you close apps, and Settings > Battery shows which apps used the most screen and background time. No app can list running processes with their CPU use.
How can I see which apps are running in the background?
iOS does not show a live list. Settings > Battery shows background activity per app over the last 24 hours or 10 days, and Settings > General > Background App Refresh lets you switch it off for any app.
Is there an iPhone CPU temperature monitor?
No app can read the CPU temperature in degrees; iOS does not provide it. What apps get is the thermal state (Normal, Elevated, Serious, Critical), which Device Monitor shows for free in Device Info.
Is there a CPU usage widget for iPhone?
Device Monitor has a Home Screen widget with a CPU bar, but read it with care: it shows the widget's own process, so it sits near 0 %. The RAM, storage and battery figures on the same widget are the useful part.

You might also like

More Device Monitor guides