If you are buying 4x6 thermal labels in Australia, the listings can get annoying fast. One seller calls them 4x6. Another calls them 100x150mm. Someone else says A6 shipping labels, then the roll arrives and your printer refuses to feed it.
That is before you even get to MyPost Business. Plenty of sellers buy the right thermal printer and the right labels, then still end up with an A4 PDF that prints tiny, sideways or half cut off.
This guide keeps it practical. You will learn what size to buy, how to compare direct thermal labels, what to check before ordering from Australian suppliers, and how 4x6 thermal labels fit into a MyPost Business workflow.
In this article:
- What 4x6 thermal labels mean in Australia
- How to choose 4x6 thermal labels Australia sellers can rely on
- Do 4x6 thermal labels work with MyPost Business?
- Where to buy 4x6 thermal labels in Australia
- Common 4x6 thermal label problems
- Related reading
- Final take
What 4x6 thermal labels mean in Australia
A 4x6 thermal label is a shipping label about four inches wide and six inches tall. In metric terms, exact 4x6 is 101.6x152.4mm.
In Australia, most sellers and suppliers use 100x150mm as the everyday equivalent. You will see both terms used for the same shipping label job.
That tiny size difference usually does not matter for parcel labels. It can matter inside your printer settings though. If your driver is set to true 4x6 but your roll is 100x150mm, you may see slight clipping, drift or off centre printing.
4x6, 100x150mm and A6 are close, not identical
Here is the simple version:
| Name used in listings | Actual size | What it usually means | |---|---:|---| | 4x6 inch | 101.6x152.4mm | Common thermal shipping label size | | 100x150mm | 100x150mm | Common Australian metric shipping label size | | 102x152mm | 102x152mm | Another near 4x6 size, often used by label suppliers | | A6 | 105x148mm | Close, but not the same as 100x150mm |
If you only remember one thing, remember this: buy the label stock your printer supports, then set the printer driver to that exact size.
A seller can use 100x150mm labels all day without trouble. Problems start when Windows, macOS, Chrome, Acrobat and the printer driver all think the page is a different size.
Direct thermal is the normal choice for shipping
Most 4x6 shipping labels are direct thermal labels. They do not need ink, toner or ribbon. The printer head heats the label surface and turns it black where the barcode and address need to print.
Thermal transfer labels are different. They use a ribbon and suit longer life labels, product labels, warehouse labels or labels exposed to more heat and rubbing.
For Australia Post, eBay, Shopify, Etsy and Amazon AU parcel labels, direct thermal is normally the cleaner choice. Your parcel label only needs to survive picking, transport and delivery. It does not need to stay perfect on a warehouse shelf for years.
How to choose 4x6 thermal labels Australia sellers can rely on
The cheapest roll is not always the cheapest label. A roll that jams, prints faint barcodes or peels off recycled cartons costs you time and replacement stock.
Before you order a box of labels, check the specs against your printer and your packing setup.
Match the label format to your printer
Most desktop thermal printers use either rolls or fanfold stacks.
Roll labels suit compact desks and printers with internal roll holders. They are tidy and easy to store. The catch is that the core size and outer roll diameter must fit your printer.
Fanfold labels sit behind the printer and feed through the rear slot. They suit higher volume benches because the stack holds more labels and does not curl around a roll. They also need more bench space.
Check these before buying:
- Maximum label width your printer supports
- Roll core size, often 25mm, 38mm or 76mm depending on the printer
- Maximum outer roll diameter
- Whether your printer supports fanfold labels
- Gap sensing or black mark sensing
- Whether the label stock is direct thermal or thermal transfer
Printers such as Zebra, Brother, Dymo, MUNBYN and other 4 inch thermal printers can all print shipping labels, but they do not all feed the same stock. Dymo 550 series buyers should be extra careful because some newer models can be picky about compatible rolls.
Compare cost per label, not pack price
Suppliers package labels in different ways. One listing might look cheaper until you realise it has fewer labels per roll or higher shipping.
Use this basic calculation:
pack price ÷ number of labels = cost per label
Then check:
- GST and shipping cost
- Delivery speed inside Australia
- Labels per roll or labels per fanfold stack
- Whether you need a roll holder
- Supplier return policy if the labels do not feed well
- Whether you are already buying mailers, tape or cartons from the same supplier
For a small eBay seller, grabbing a small pack locally may make sense. For a Shopify store shipping daily, bulk boxes from a packaging or label specialist can reduce the per label cost.
Check adhesive and barcode print quality
A parcel label has two jobs. It needs to stay stuck to the parcel, and the barcode needs to scan.
That sounds obvious, but cheap labels can fail in boring ways. Some peel from recycled satchels. Some print grey instead of dark black. Some have rough perforations that tear badly when you are packing quickly.
If you ship in summer, store direct thermal rolls away from heat and sunlight. Direct thermal labels can darken or fade if they sit in a hot car, near a window or beside a heater.
For regular parcel shipping, you do not need fancy label stock. You do need labels that feed cleanly and produce dark, sharp barcodes.
Do 4x6 thermal labels work with MyPost Business?
Yes, 4x6 thermal labels work with MyPost Business. Australia Post does not force you to use a particular thermal printer brand for normal parcel labels.
The official MyPost Business workflow lets you create shipments and print labels. The awkward part is what the downloaded PDF looks like on your computer.
Some sellers get a thermal friendly label. Many get an A4 PDF with the label sitting in one corner. If you send that full A4 page to a 100x150mm printer, the printer has to guess what to do.
The A4 PDF problem
A thermal printer expects the page size to match the loaded label. MyPost Business labels often arrive as A4 PDFs because A4 works for office printers and legacy workflows.
That creates the classic seller headache:
- Download the label from MyPost Business.
- Open the PDF in Acrobat, Chrome or Preview.
- Pick the thermal printer.
- Set the paper to 100x150mm or 4x6.
- Print a test label.
- Discover it is tiny, cropped, rotated or off centre.
- Waste another label while changing scale settings.
The label content is usually fine. The page around it is the problem.
Recommended MyPost Business setup
For 4x6 thermal labels Australia Post sellers should start with these settings:
- Set your printer paper size to the actual stock, usually 100x150mm.
- Turn off "fit to page" if it shrinks the label.
- Use actual size or 100% scale when the PDF is already 4x6.
- Crop the A4 PDF first if the label is sitting inside an A4 page.
- Calibrate the printer after changing label rolls.
- Print one test label before sending a batch.
If you process a few orders a week, manual cropping may be tolerable. If you ship every day, the repeated cropping and scaling gets old quickly.
That is the gap LabelChop was built for. It watches your Downloads folder, detects MyPost Business A4 PDF labels, crops them to 4x6 and sends them to your thermal printer.
Where to buy 4x6 thermal labels in Australia
There is no single best supplier for every seller. The right place depends on order volume, delivery speed, printer model and whether you care about packaging materials beyond labels.
You will usually compare three supplier types.
Packaging suppliers
Packaging suppliers are handy when you want labels, mailers, cartons and tape in the same order. For example, AwesomePack is a useful Australian reference point for ecommerce packaging supplies.
HeapsGood is another supplier worth checking if your brand already leans toward lower impact packaging. For those stores, the cheapest cost per label may not be the deciding factor.
When comparing packaging suppliers, check whether the listing clearly says direct thermal, 100x150mm and compatible with your printer style. Do not rely on the word "shipping" alone.
Label specialists
Label specialists can help when you need more exact specs. That might mean a specific core size, fanfold cartons, stronger adhesive or a printer that is fussy about label sensing.
This path makes more sense once your shipping volume grows. At that point, a small difference in cost per label matters, but feed reliability matters more.
If a supplier lists technical details clearly, that is a good sign. You want actual dimensions, roll specs, material type and compatibility notes, not just a photo of a white roll.
Marketplaces and office retailers
Amazon AU, eBay Australia and office retailers can be good for testing or emergency restocks. They are easy to search and often ship quickly.
The trade-off is inconsistency. Two listings can use the same title and sell very different stock.
Before ordering from a marketplace, read the specs slowly. Check label count, actual dimensions, core size, return policy and recent reviews that mention barcode darkness, jamming or adhesive.
Common 4x6 thermal label problems
Most label problems come from a mismatch between the PDF, printer driver and label stock. The printer is rarely broken.
The label prints too small
This usually means the software is shrinking an A4 page down to a 100x150mm label.
Fix it by cropping the PDF to the label area first, then printing at actual size. If the file is already 4x6, turn off any setting that says fit, shrink or scale to printable area.
The label is cut off
A cut off label usually means the page size is bigger than the physical label, or the printer is starting from the wrong edge.
Set the paper size to match the stock. Then calibrate the printer so it can detect the gaps between labels.
The printer feeds blank labels
Blank labels usually mean one of three things.
- The roll is loaded upside down
- The printer is a thermal transfer model but no ribbon is installed
- The stock is not direct thermal label stock
A quick test is to scratch the label surface with a fingernail or coin. Direct thermal stock usually darkens where you scratch it.
The barcode looks grey or fuzzy
Grey barcodes can come from low darkness settings, poor label stock or a worn print head.
Increase darkness in small steps, clean the print head and test another roll if you have one. Do not crank darkness to maximum unless you need to, because it can reduce print head life.
The label prints off centre
Off centre printing often comes from calibration or a size mismatch. It also happens when an A4 MyPost Business label has been cropped badly.
Recalibrate after loading a new roll. If you are cropping manually, make sure the crop box starts at the label edge, not the A4 page edge.
Related reading
If you are setting up the whole label workflow, these guides will help:
- How to print MyPost Business labels on a thermal printer
- How to crop MyPost Business A4 labels to 4x6
- Best thermal printers for Australia Post labels in 2026
- Shipping label printing problems and how to fix them
- Thermal vs inkjet for shipping labels
Final take
For most Australian ecommerce sellers, the safe starting point is 100x150mm direct thermal labels. They are the local version of 4x6 shipping labels and they suit most MyPost Business, eBay, Shopify, Etsy and Amazon AU parcel workflows.
Buy labels that match your printer, not just the cheapest listing. Check roll size, core size, direct thermal stock, feed type and real cost per label before ordering in bulk.
If MyPost Business still gives you A4 PDFs, the label stock is not the problem. You need to crop or convert the PDF before printing. LabelChop handles that part automatically, so your thermal printer gets the 4x6 label it expected in the first place.
You can see plans on the pricing page, or check common setup questions in the FAQ.