Check live network bandwidth on Mac

There’s a difference between “what speed is my ISP giving me” (a speed test) and “how much bandwidth is my Mac using right now.” The first is a once-a-month sanity check; the second is what you actually want when downloads slow down, a video call freezes, or you’re wondering if Time Machine is hogging the line.

How to read live throughput

Activity Monitor

1. Open Activity Monitor, click Network.
2. The bottom panel shows live Data received/sec and Data sent/sec for the whole system.
3. The graph plots packets/sec or bytes/sec — toggle with the dropdown next to it.
4. The top list breaks the throughput down per process when you sort by Rcvd/Sent Bytes/sec.

Apple reports in bytes, not bits. Multiply by 8 to get Mbps when comparing to your ISP advertised speed (1 MB/s ≈ 8 Mbps).

Terminal: nettop and netstat

nettop -P -m route shows per-process bytes per interval. For raw interface counters, netstat -ibn lists bytes in/out per interface; sample it twice a second apart and subtract for current throughput. Crude but reliable.

There’s also iftop (via Homebrew) if you want an ncurses live view by remote host.

Speed tests

For the “is my ISP delivering” question: networkquality is a hidden gem built into macOS — Apple’s own speed test, in Terminal.

networkquality

It gives you upload, download, and a “responsiveness” score (round-trip count under load), without installing anything.

A menu bar monitor

For ambient awareness, this is the right tool. Beacon’s Network readout sits in the bar and updates roughly once a second.

1. Install Beacon.
2. Enable Network in Settings > Menu Bar. Choose Mbps if you prefer that to MB/s.
3. Pick separate up/down arrows or a single combined readout.
4. Click for top processes and a recent throughput graph.

A few gotchas

• Wi-Fi link speed isn’t throughput. The “780 Mbps” you see when you Option-click the Wi-Fi menu is the negotiated link rate. Actual usable bandwidth is typically 40-70% of that.
• VPNs cap throughput — the VPN process can become the bottleneck before your network is. Worth checking VPN process CPU when bandwidth feels low.
• iCloud, Time Machine, Photos happily use whatever’s available unless throttled. The “low data mode” toggle in Network settings is worth knowing about.
• Background updates from the App Store and OS happen on a schedule and can saturate a slow connection without you knowing.

Having a live readout helps you spot all four within seconds instead of guessing.