Hotspots and data

Mac uses Personal Hotspot data in the background

A Mac on a phone hotspot can use a lot of data with no action from you. Find the apps that use it, then pause them.

Applies to: macOS 13 Ventura and later for the System Settings paths. nettop is in all current macOS versions.Checked: 29 October 2026

Symptoms

The phone's data plan goes down fast while the Mac is connected to its Personal Hotspot.
The carrier sends a warning that the data limit is near.
The hotspot is slow, although you only read email or web pages.

Likely causes

Cloud sync. iCloud Drive, iCloud Photos and other sync apps upload and download changes when a connection is available.
Updates. macOS, the App Store and app updaters can download large updates in the background.
Backups and large uploads. Cloud backup apps can upload many gigabytes after a long time offline.
Apps that ignore the network type. macOS marks Personal Hotspot as an expensive network, but each app decides what to do with that information.
Video and streaming. Video apps can choose a high quality when the hotspot is fast.

How to check

Open Terminal. Show the processes that use expensive interfaces, such as a hotspot. Press q to stop.
```
nettop -P -t expensive
```
Output One row per process, with the bytes in and bytes out on the expensive interface.
To see only the change since you started, add -d. Let it run for one minute.
```
nettop -P -d -t expensive
```
Open Activity Monitor from Applications > Utilities. Click Network.
Click the Sent Bytes or Rcvd Bytes column to sort the processes.

How to fix it

Turn on Low Data Mode for the hotspot. Choose Apple menu > System Settings > Wi-Fi.
Click Details next to the hotspot network. Turn on Low data mode. Click OK.
Pause sync in apps that do not obey Low Data Mode. Use the menu or settings of each app.
Stop automatic macOS downloads while you tether. See Stop Software Update downloading on a hotspot.
Quit apps that you do not need. Quit cloud backup apps until you are on your usual network.
Run nettop again after some minutes. Make sure that the data use is lower.

With Kilobat

See live upload and download for each app in the menu-bar popover. This is free. See See which app uses data on a hotspot.
Use the same view in Terminal.
```
kilobat status --watch
```
Switch to the Travel profile to block the apps that you did not allow. This needs Pro and the network filter.
```
kilobat profile travel
```
Set a data budget for the hotspot. With the filter on, new connections stop at the limit. See Set a monthly data budget that resets on renewal day.
```
kilobat limit 2
```
With the filter on, Kilobat pauses updater helpers on metered networks. See Stop updates from using hotspot data.

Questions

Does macOS know that my Mac uses a hotspot?

Apple's documentation says that macOS marks cellular and Personal Hotspot connections as expensive. Apps can read this. Other phones' hotspots can look like usual Wi-Fi. See Make a Mac treat a network as metered.

Does Low Data Mode stop all background data?

No. Apple describes it as a way to reduce data use on that network. Apps decide how much they reduce.

Why does the carrier figure differ from what the Mac shows?

The carrier counts all devices on the hotspot and the phone itself. The Mac counts only its own traffic. See Compare Kilobat with your carrier's data figure.

Sources

nettop(1), man page installed with macOS 27.2
Apple Developer: NWPath isExpensive
Apple Support: Wi-Fi settings on Mac
Apple Support: View network activity in Activity Monitor on Mac
Kilobat docs: Hotspots and data cost

Sources checked on 29 October 2026. Man pages are the ones installed with macOS; open one with man <name> in Terminal.