LabelChop

Royal Mail label size guide for 6x4 printing

Royal Mail label size guide for 6x4, A4 and thermal printer settings, with fixes for tiny, cut off or badly scaled PDFs.

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Cover Image for Royal Mail label size guide for 6x4 printing

Royal Mail label size sounds like a boring detail until the printer ruins a batch.

You buy postage, download the label, send it to the thermal printer and expect a clean 6x4 label. Instead, it prints tiny in one corner, cuts off the barcode, rotates sideways or leaves half the roll blank.

The fix is usually not a new printer. It is making the PDF page size, printer driver and physical label stock agree before you print.

Royal Mail label size guide showing PDF page size, printer driver size and 100 percent thermal printing

In this article:

The short answer on Royal Mail label size

For thermal printer workflows, the common target is a 6x4 inch shipping label.

You may also see that described as 4x6, about 100x150mm, 102x152mm or a size close to A6. Those names are close enough to confuse people, but they are not always identical in printer drivers.

Use this rule before printing:

  1. Check the PDF page size.
  2. Check the printer driver paper size.
  3. Check the physical label size loaded in the printer.
  4. Print at actual size or 100 percent scale when the PDF is already a 6x4 label.

If the PDF is a full A4 page, do not send that whole page straight to a 6x4 thermal printer. Crop or convert the label first.

6x4, 4x6, 100x150mm and A6 explained

The label-size names are annoying because suppliers, printers and carriers do not always say them the same way.

Here is the practical version.

| Label name | Approximate size | What it means for printing | |---|---:|---| | 6x4 inch | 152.4x101.6mm | Common UK shipping label wording, often landscape | | 4x6 inch | 101.6x152.4mm | Same physical stock, often described width first | | 100x150mm | 100x150mm | Common metric thermal label stock | | 102x152mm | 102x152mm | Another common 4x6 thermal stock size | | A6 | 105x148mm | Close to 6x4, but not exactly the same | | A4 | 210x297mm | Office paper size, not a thermal roll label |

A few millimetres difference does not always matter if the label is centred and the barcode has enough quiet space. It does matter when a driver clips the edges, rotates the file or shrinks the whole PDF to fit a slightly different page.

Visual comparison of a native 6x4 Royal Mail thermal label and an A4 page containing a shipping label

If your printer driver offers the exact size of your roll, choose that. If your labels are sold as 100x150mm, use 100x150mm. If they are sold as 4x6, use 4x6 or create a custom size that matches the roll.

A6 is close, but do not assume it is safe if your barcode is clipping or the label drifts. Create the real paper size instead.

A4 Royal Mail PDFs versus thermal labels

A4 is not wrong by itself. It is wrong when you send a full A4 page to a 6x4 thermal printer and expect the printer to guess which part is the label.

There are two different cases:

Native thermal PDF: the PDF page itself is already 6x4 or close to your label stock. Print it at actual size.

A4 PDF with a label inside: the PDF page is A4, and the shipping label sits somewhere on that page. Crop or convert the label area before thermal printing.

The second case is where people get tiny labels. The print dialog sees a full A4 page and scales the whole thing down to fit the 6x4 label. The real label inside the A4 page becomes smaller again.

If you are using an office printer with A4 paper, that may be fine. If you are using a Dymo, Zebra, Brother, MUNBYN, Rollo or similar 4 inch thermal printer, it is the wrong input.

Click & Drop settings to check

Royal Mail Click & Drop workflows can vary by account, service, browser and label format. If you need the full setup path, use the Royal Mail Click & Drop label printer workflow alongside this size checklist.

When you set up a workstation, check these items.

Choose a thermal label format where available

If Click & Drop or your connected workflow gives you a thermal, 6x4 or label-printer-friendly option, use that before trying a workaround.

A native thermal PDF usually means less cropping, less scaling and fewer wasted labels.

Download the PDF and inspect the page

Open one label before printing a batch. If it fills the page like a proper 6x4 label, print at actual size. If it sits inside an A4 page, crop or convert it first.

Do not rely only on the preview thumbnail. Browser previews can make an A4 page and a 6x4 page look deceptively similar.

Avoid browser settings that resize labels

Browser print dialogs are convenient, but they can remember bad settings.

Watch for these options:

  • Fit to page
  • Shrink to printable area
  • Scale to paper size
  • Borderless enlargement
  • Headers and footers
  • Margins added by the browser

For a true 6x4 PDF, use 100 percent scale or actual size. For an A4 PDF, crop first, then print the cropped output at actual size.

Printer driver settings for 6x4 labels

The printer driver is the boring bit that saves the whole setup.

Set the paper size in the operating system, not only in the browser. That way Chrome, Edge, Acrobat, Preview and your shipping apps all start from the same default.

Diagram showing the Royal Mail PDF, printer driver and thermal printer settings chain for clean 6x4 output

Use this baseline:

  • Paper size: 6x4, 4x6, 100x150mm or your exact custom label size
  • Scale: actual size or 100 percent
  • Orientation: whichever fills the label without clipping
  • Margins: none or the smallest available setting
  • Media type: direct thermal if the driver asks
  • Darkness: strong enough for sharp barcodes, not so dark that bars bleed
  • Speed: reduce speed if barcodes look fuzzy

Then calibrate the printer after loading a new roll or fanfold stack. Calibration tells the printer where each label starts and ends. If every label drifts lower down the roll, calibration is usually the first fix.

Fix tiny, cut off or sideways Royal Mail labels

Most Royal Mail label-size problems are repeatable. Work through them in order.

Troubleshooting checklist for Royal Mail labels printing too small, cut off, sideways or drifting on a thermal printer

The label prints tiny

This usually means a full A4 PDF is being shrunk onto a 6x4 label. The same root cause is covered in more detail in the shipping label printing too small troubleshooting guide.

Fix it like this:

  1. Open the PDF and check whether the page is A4.
  2. If it is A4, crop or convert the label area first.
  3. Set the thermal printer paper size to the real label stock.
  4. Print the cropped label at actual size.
  5. Turn off fit to page.

If you skip the crop step, the printer will keep treating the A4 page as the thing to fit.

The barcode is cut off

A cut off barcode usually means the page is larger than the selected paper size, the orientation is wrong or the printer starts in the wrong place.

Check the driver paper size first. Then check orientation. Then recalibrate the printer.

Do not ship a label with a clipped barcode just because the address is readable. Scanning is the point of the label.

The label is sideways

Sideways labels happen when the PDF orientation and printer orientation disagree.

If the PDF is already the right size, rotate in the print dialog or change orientation in the driver. If the PDF is A4, crop first. Rotating an uncropped A4 page does not solve the page-size problem.

The label looks blurry

Blurry labels are usually caused by scaling, low print density, poor label stock or printing too fast.

Print at 100 percent, increase darkness one step, reduce speed and make sure the label stock is direct thermal. If the bars bleed together, reduce darkness again.

When to use an automatic PDF fixer

Manual setup is fine if you print a few labels a week and your Royal Mail PDFs already arrive as clean 6x4 pages.

Automation starts to make sense when the same PDF work keeps coming back:

  • Download label
  • Open PDF
  • Realise it is A4 or the wrong size
  • Crop or screenshot the label area
  • Change print settings
  • Print a test label
  • Fix scale
  • Repeat for the next batch

That is the workflow LabelChop is built for. It watches your Downloads folder, detects compatible shipping-label PDFs, crops or resizes them to 4x6 output and sends them to your thermal printer.

For Royal Mail, the careful wording matters. LabelChop is not an official Royal Mail integration. It helps with compatible PDFs from Royal Mail, Click & Drop, marketplaces and other shipping workflows when the PDF format is awkward.

If you want to test the crop step before installing anything, try the free A4 to 4x6 shipping label converter. If cropping fixes the tiny-label problem, automating that step is the next obvious move.

Final label-size checklist

Before printing a batch, check this list:

  1. The label PDF is a thermal-friendly page, or the A4 page has been cropped.
  2. The driver paper size matches the loaded label stock.
  3. The print scale is actual size or 100 percent.
  4. Browser margins, headers and fit-to-page options are off.
  5. The printer has been calibrated after loading labels.
  6. The barcode is dark, sharp and fully inside the label edge.
  7. One test label prints correctly before you send the whole batch.

If all seven are true, the label size is no longer the bottleneck. If you still have to crop the same kind of PDF every shipping day, let software handle that boring step and keep your time for the orders.

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