I measured what my meeting notes app uploads. Notion sent 115 MB for 10 minutes.

I wanted to know a simple thing: when a meeting notes app records a meeting, how much of it leaves the laptop? So I recorded the same 10-minute meeting with two apps on one Mac and logged every byte each one sent.

The result

Notion sent 115.7 MB while it recorded, steadily, at about 1.5 Mbit/s for the full 10 minutes. That's 6 times the size of the WAV. It's also almost exactly what 10 minutes of uncompressed 48 kHz audio weighs (115.2 MB). I can't see inside the traffic, so I can't say what format it is, only that the size matches. The upload happens live, while you record, not after you press stop.

Lyonesse sent 0.02 MB while recording. Transcription, speaker detection and the summary all ran on the Mac.

Full disclosure, and two things about Lyonesse

I make Lyonesse, the other app in this test. It's a meeting notes app that transcribes on your device, so take the comparison with that in mind. Everything here is reproducible, and the scripts and data are linked at the end.

• It downloaded 18 MB on first use. That's the optional speaker detection models, fetched once. It's a download, not an upload.
• About 0.4 MB went to iCloud after the recording, through macOS's own sync. That's the note's text syncing to your other devices, not the audio, since the audio file is several MB.

Why only two apps

I planned five. Granola wouldn't let me sign up without a work Google or Microsoft account, and Otter needed a free trial before I could try it. You can't even try most of them without an account or a trial. Notion was the one that just worked on a free plan, and it's also the one with the biggest install base, so it's the comparison that matters most.

This isn't a security audit

Cloud transcription needs your audio. That's how it works, and for a lot of people it's a fair trade. This post just shows what that trade looks like in bytes, so you can decide with numbers instead of guesses. Notion isn't doing anything it doesn't tell you it does.

Check any app on your own Mac

You don't need any of my scripts for a quick look. Open Activity Monitor, go to the Network tab and sort by Sent Bytes, and you'll see how much every running app has sent since it started. For a per-app count you can log over time, run this in Terminal:

nettop -P -L 1 -J bytes_in,bytes_out -x

It prints one line per app with bytes in and out. Drop the -P and you get every connection with its remote address. No sudo needed.

How I measured

• One Mac (macOS 27.0.1), one home Wi-Fi network, one day, default settings, free plans.
• The clip is 10 minutes of a real four-person design meeting from the AMI Meeting Corpus (ES2004a, CC BY 4.0), played through the speakers at a fixed volume, so each app heard it through the mic like a real meeting.
• nettop logged every process's bytes in and out per connection about once a second. No sudo, no proxy, no decryption, only byte counts.
• Each run: record the clip, stop, wait for the summary, wait 3 more minutes, then turn Wi-Fi off and try a 1-minute recording, then reconnect and wait 3 minutes for any catch-up upload. A 15-minute control run with no meeting app shows the background noise of a quiet Mac: about 0.03 MB.
• Lyonesse was recorded with its plain Record button, mic only. Network numbers don't depend on that.
• Very short connections, under about a second, can be missed. A 115 MB upload isn't one of them.

Data and scripts

• notion.csv, lyonesse.csv and control-system.csv: bytes sent and received per process, per phase
• run.sh: the runner
• analyze.mjs: the analysis, bytes per phase and where they went
• README.md: what each file is, and the clip's source and license

If you run it on your own Mac, I'd love to see what you get, especially for apps I couldn't test.

Test audio: AMI Meeting Corpus (ES2004a), University of Edinburgh, CC BY 4.0.