MUNBYN RW403B setup for Windows, Mac and phones

Check the model and decide how you will print

Read the model label on the machine: this guide is for the RW403B. Instructions for an ITPP130B, RW402B or an AirPrint model can look similar while using different software or buttons. Keep the supplied power adapter, data cable and any USB adapter together until setup is complete.

The RW403B is a 203 dpi direct thermal printer with USB and Bluetooth connections. Its supported label width range is 40–108 mm. For ordinary parcel dispatch, nominal 4×6-inch direct thermal stock is a useful starting point; the exact dimensions still need to agree with the print settings.

Choose one route for your first print. A computer on USB offers a direct way to check the driver and PDF settings. A phone needs the Munbyn Print app. Desktop Bluetooth is a separate browser workflow. Getting one route working before adding another makes a fault easier to locate.

Download software from MUNBYN’s RW403B driver listing. Check your operating system and processor before installing. This matters especially for Windows computers using ARM processors: the current Windows help article includes a note naming a different model, RW405B, so it is insufficient evidence to promise RW403B support for every ARM laptop.

Load suitable stock with a clear feed path

Put the printer on a firm surface with space behind it for the supply. Keep a fanfold stack level; use a suitable holder for an external roll. Labels should reach the entry straight, without catching a laptop cable, desk edge or packing tape dispenser.

Follow the RW403B loading diagram for the coated side and paper guides. Guides should support the liner without squeezing it. Keep several consecutive labels available for the machine’s recognition procedure, close the cover fully and let it finish moving the stock before sending a job.

Use direct thermal labels within the printer’s supported dimensions. A Brother DK roll or DYMO Series 5 supply is a different system. Our thermal label buying guide explains those boundaries and the choice between rolls and fanfold stacks.

The fanfold pack below suits a straightforward external feed without needing a roll spindle. Check the pack’s actual dimensions against the paper size you select; “100 × 150 mm” and exact 4×6 inches are close, but not identical.

Windows: establish a USB connection first

1. Connect the supplied power supply and switch the printer on. Connect its data cable to the computer, using the appropriate adapter if required.
2. Obtain the current RW403B Windows driver from MUNBYN. Follow its installer prompts. The maker also describes a driver download file on the removable drive that appears when the printer is connected.
3. Open Windows Settings → Bluetooth & devices → Printers & scanners. Check that the RW403B print queue is present, then open its printing preferences.
4. Set the page dimensions to your stock. For exact 4×6-inch labels, that is 101.6 × 152.4 mm; a driver may round the displayed name. Check the actual setting rather than relying on its friendly name.

Use the RW403B queue when printing from your PDF application. If several old MUNBYN queues are present, identify which belongs to the connected machine before sending repeated jobs. A document waiting in another queue will not be repaired by changing the labels.

Mac: install the matching driver and check the queue

MUNBYN’s USB instructions require a driver on the Mac too. Connect the powered printer by its data cable, install the current RW403B Mac package and follow the maker’s steps to add the printer in System Settings → Printers & Scanners.

If the printer does not appear, check the cable at both ends and restart the printer. Confirm that the connection carries data: a cable or adapter that only supplies power is not sufficient. MUNBYN’s Mac discovery guide covers adding RW403B after installation.

In the PDF print dialogue, select that queue and the correct paper dimensions. Save a useful preset after the first correct print, giving it a clear name such as “RW403B parcel labels”. Recheck it when changing stock or after a software update.

iPhone and Android: connect inside Munbyn Print

MUNBYN’s current phone guide names Munbyn Print, available through the phone’s app store. Switch on the printer and Bluetooth, open the app, choose the 4 inch printer category and select RW403B. Allow the Bluetooth and local file permissions needed for the printing workflow.

The guide describes a successful connection message and a blue Bluetooth status light. Import the postage file into the app; MUNBYN recommends PDF. Check the label dimensions and orientation before printing. Keep the original downloaded file rather than replacing it with a screenshot that may reduce barcode clarity.

If discovery fails, confirm the printer is powered on and search again within the app. This is different from expecting the printer to appear in the iPhone’s native AirPrint list. Use the official phone connection guide if the app’s screens differ from an older tutorial.

Desktop Bluetooth: MUNBYN Editor is a separate route

For supported computers, MUNBYN documents an online Bluetooth workflow through MUNBYN Editor in Chrome. Turn on Bluetooth and the printer, open the official editor, sign in and select the device and label dimensions. Use its printer pairing and Bluetooth printing controls.

This route includes an account and browser connection step; pairing in the computer’s Bluetooth settings alone does not establish that every PDF application can print wirelessly. For routine PDF dispatch from a desktop application, USB with the matching driver may be the more convenient workflow. Choose according to how you actually create postage, rather than assuming every connection behaves the same way.

Make the PDF, paper and preview agree

Before the first job, check three dimensions: the document page, the physical label and the selected printer paper size. A carrier’s A4 PDF can contain a small postage area surrounded by blank paper. Shrinking that whole page onto a four-inch label produces a miniature postage label.

Select thermal output in the postage service where offered. Follow that service’s print instructions, inspect the preview and avoid accidental scaling. Print one label, check that the address and every barcode are complete, then continue with the batch. See 4×6 versus A4 shipping labels for the format decisions.

Diagnose the symptom before changing settings

Tiny but complete label: inspect the PDF page size and scaling. The same edge missing every time: check orientation, printable area and paper dimensions. Each label drifts further down the stock: check the label length, gap setting and recognition procedure. Treat these as different faults.

MUNBYN’s offset guidance says the configured gap should match the physical gap. Do not copy a gap value from another brand’s roll. Increasing darkness cannot fix a page-size mismatch, and moving the artwork cannot correct a feed length that is wrong on every label.

For a solid red light, no feed response or an out-of-paper message despite loaded stock, MUNBYN provides a distinct sensor calibration procedure. It starts with the printer off and no paper loaded. Follow that model-specific procedure, rather than trying button combinations from another MUNBYN machine. If the problem persists, record the connection, file size, stock dimensions and error for support.

For a label already on your phone, follow the iPhone printing walkthrough or Android printing walkthrough to get the PDF out of the order and into the right print app.

Manufacturer guidance used for this page

Reviewed in November 2026 using manufacturer setup instructions.

• RW403B UK specifications
• Windows USB installation and Mac USB installation
• MUNBYN Editor Bluetooth workflow
• Paper size and gap settings