How to see how much data your Mac used this month
Why macOS has no monthly data counter, what netstat shows since startup, and practical ways to track a Mac's data use on a hotspot or capped plan.
Does a Mac track monthly data usage?
No. Activity Monitor and nettop count since each process started; nothing in macOS keeps a running monthly total.
How do I see total data used since startup?
netstat -ib | awk 'NR==1||/en0/'Ibytes and Obytes are bytes received and sent on Wi-Fi (usually en0) since the Mac started.
How do I track data on a hotspot?
The phone's own cellular data screen counts what the Mac used through it. Turning on Low Data Mode for that network reduces background use: reduce Mac data usage.
Common questions
How do I check data usage on my MacBook?
netstat -ib shows bytes since startup; per app use is in Activity Monitor's Network tab.
Can I reset data usage on a Mac?
There is no monthly counter to reset; the counts restart when the Mac restarts.