How NotchStar measures network speed
NotchStar shows your current download and upload speed next to the rings in the System tab. The figures are bytes per second, measured from your WiFi and Ethernet interfaces, and they update once a second while the tab is open.
How it is measured
Your Mac keeps a running count of bytes received and sent on each network interface. NotchStar reads those counters every second and divides the difference by the time between the two reads. It only counts interfaces whose names start with en, which covers WiFi and Ethernet. VPN tunnels and other virtual interfaces are left out, because their traffic also passes through the real interface and would be counted twice.
The counters are 32 bit and wrap around. NotchStar works out each interface’s change on its own, so a wrap does not produce a huge false spike.
Reading the units
The readout switches unit as the number grows: B/s, KB/s, MB/s, then GB/s, each step being 1024. These are bytes, not bits. Internet plans are usually sold in bits, so divide the plan by eight to compare.
Limits
- A dash shows until the second sample, about one second after opening the tab.
- It is a total for the Mac. It does not say which app is using the bandwidth.
- It measures traffic, not the speed your connection could reach. It is not a speed test.
For the other rings, see the System stats feature page and what the CPU gauge shows. To see how it compares with Activity Monitor’s Network tab, read NotchStar System vs Activity Monitor.
