What Windows Telemetry Actually Sends — and How Much You Can Really Turn Off

What actually leaves your machine

Two services do almost all of the talking: DiagTrack, listed in services.msc as "Connected User Experiences and Telemetry", and Windows Error Reporting, which handles crash data. The required tier sends device inventory — hardware model, CPU, RAM, disk layout, OS build, language and region — plus health events such as failed updates, boot problems and application crashes. That is the layer Microsoft uses to decide which patches go where, and running a safe update pipeline without it is genuinely difficult. What it is not, despite forum folklore, is a live stream of your documents.

The optional tier differs in kind, not just in volume. Switch it on and Windows adds app usage and app performance details, inking and typing samples that train the prediction model, websites visited in Edge, and richer error reports — including full memory dumps. That last item is the strongest honest argument in this whole debate: a memory dump can contain fragments of whatever was in RAM, including pieces of the document you had open when something crashed. On a clean install optional data is off, but years of upgrades and express-setup routines leave it quietly on more often than people think.

The switches that actually matter

Ten minutes in Settings covers everything that matters. Open "Privacy & security" > "Diagnostics & feedback" first, then walk through "General" and Activity history right after — the names differ slightly between Windows 10 and 11, but the switches are the same. Every one of them is reversible, none of them breaks Windows Update, and the whole set fits into one coffee break. Do it once and the configuration holds for the machine's entire life.

• Optional diagnostic data — off, under Settings > Privacy & security > Diagnostics & feedback; the single biggest cut
• Inking and typing personalization — off, so your typing samples stop training the prediction model
• Advertising ID — off, under Privacy & security > General; apps still show ads, just untargeted ones
• Activity history — off, cleared, and untick sending it to Microsoft
• App-launch tracking — off; the Start menu and search work perfectly without it
• Tailored experiences and suggested content — off, mostly for the silence

What stays on — and whether you should care

The required tier cannot be turned off on Home or Pro, and pretending otherwise costs you an evening. The AllowTelemetry value under HKLM\SOFTWARE\Policies\Microsoft\Windows\DataCollection does accept a 0, and the Group Policy editor will let you write it — but outside Enterprise and Education editions, Windows silently falls back to the required level. The same goes for blocking telemetry endpoints in the hosts file: it has repeatedly broken Windows Update and Store deliveries, which is a bad trade for hiding a hardware inventory from Microsoft. The required core contains no document content and no browsing history.

So the honest scoreboard reads: turning off optional data removes everything that could plausibly leak user content, and the remainder is metadata about the machine itself. For most people that is a fair price for a self-maintaining operating system. If your threat model says otherwise, the real answers are Enterprise policy on managed hardware or network-level filtering with the update-breakage risk accepted consciously — not a checkbox hunt.

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