HP "Paper Mismatch" — Three Settings Must Agree, Here's Where Each One Lives

By Ryan Green · Updated August 2026 · Independent guide · PrinterCare USA LLC (not affiliated with any printer manufacturer)

Quick answer "Paper Mismatch" fires when the size the printer believes is in the tray differs from the size the job requests. Three settings must agree: the printer's tray size (set on its panel after loading), the driver's default size, and the document's own size. Set all three to Letter (US) or A4 and the message stops.

Where each setting lives

Setting	Where	Set it to
Tray size (what the printer believes)	Printer panel: the prompt after loading paper, or Settings → Tray/Paper Setup → Paper Size	The paper actually loaded
Driver default	Windows: Printers & scanners → printer → Printing preferences → Paper/Quality. Mac: Printers & Scanners → Default paper size	Same as tray
Document size	The app's print dialog (and page setup in Word/Docs)	Same, or use scale/fit for foreign-size documents

Two-minute permanent fix

On the printer: reload the tray; when the size prompt appears, choose the real size. No prompt? Settings → Paper Setup → set it there.
On the computer: set the driver default (table above). This one setting stops the everyday recurrence.
For a stubborn document, print it with "Fit to printable area"/"Scale to fit" — it reconciles any size to your paper.

Special cases

Photo paper: set the exact photo size (4x6, 5x7) in the driver and load the photo tray if the model has one; "Letter" on 4x6 stock guarantees the message.
Envelopes/labels: select the media in the driver and use the guides; on LaserJets use the priority/manual feed slot.
Shared printers: each computer's driver default is independent — the one machine still set to A4 is why only one person gets the message.

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Frequently asked questions

Can I just tell it to ignore the mismatch?

Yes — press OK/Continue on the prompt, and on many models Settings → Preferences → Paper Mismatch Action can be set to "Print anyway". Fine as a one-off; fix the settings if it's every job.

Why does it happen only with PDFs?

PDFs carry their page size internally. A form created on A4 opened in the US prints with a mismatch against Letter. In the PDF print dialog choose "Fit to page" or set the size explicitly.

The tray setting resets itself.

Loading the tray triggers a size prompt on the panel on many models; whoever loads paper may be confirming the wrong size. Watch for the prompt after loading and set it once, correctly.