Also works with: This guide covers the Zebra GK420d, but the same steps apply to the Zebra GX420d and GC420d. If you have a newer ZD420 or ZD411, see our ZD420/ZD411 Setup Guide. For the older ZP 450 or LP 2844, see the ZP 450 Setup Guide.

The Zebra GK420d is one of the most popular desktop thermal printers ever made. It sits right between the older LP 2844 / ZP 450 generation and the newer ZD-series printers. If you bought one refurbished or pulled it out of a closet, this guide will get you up and running with shipping labels, barcodes, or any 4-inch label in minutes.

What This Guide Covers

• Printer Specs
• Downloads You Need
• Unboxing & Hardware Setup
• Loading Labels
• Installing the Driver
• Printing a Test Page
• Calibrating the Printer
• Troubleshooting
• Resources & Official Links

Printer Specs

Downloads You Need

Unboxing & Hardware Setup

What You Should Have

• Zebra GK420d printer
• External power adapter + power cord
• USB cable (Type A to Type B)
• Starter roll of labels (if purchased from Thermal Printer Outlet)

Connect the Power

1. Plug the power adapter into the round DC jack on the back of the printer.
2. Connect the power cord to a surge-protected outlet.
3. The printer powers on automatically. Wait for the green status light on top — this means the printer is ready.

Power Supply Note: The GK420d uses the same style external power adapter as the ZP 450. If you have a spare ZP 450 power supply, it will work. If you need a replacement, we sell them at thermalprinteroutlet.com.

Loading Labels

The GK420d loads labels from the top — very similar to the ZP 450 if you’ve used one before.

1. Open the top cover: Pull the release latches on each side of the printer and lift the cover.
2. Place the label roll: Set the roll into the label compartment with the labels feeding from underneath (labels face up as they come out the front).
3. Adjust the guides: Slide the green media guides so they’re snug against the edges of the label roll.
4. Feed the labels: Pull the leading edge of the labels past the front of the printer, extending about an inch beyond the tear bar.
5. Close the cover: Press down until it clicks on both sides.
6. Press Feed once. The printer advances one label and stops at the gap.

Label Compatibility: Use 4″ x 6″ direct thermal labels with a 1″ core for shipping labels. These are the standard UPS/FedEx/USPS size. Direct thermal labels do not need a ribbon — the print head heats the label directly to create the image. You can buy these at thermalprinteroutlet.com.

Installing the Driver

Option A: Zebra Setup Utilities (Recommended for General Use)

1. Go to the Zebra GK420d support page.
2. Download Zebra Setup Utilities for Windows.
3. Run the installer and follow the prompts.
4. When asked to select a printer model, choose Zebra GK420d.
5. Select USB as the connection port.
6. Now plug in the USB cable between your printer and computer.
7. The installer detects the printer and finishes setup.

Option B: UPS Driver (If You Only Ship UPS)

1. Download the UPS Zebra Driver.
2. Run the installer. It installs the driver optimized for UPS label formats.
3. Your printer appears as “UPS Thermal” in Printers & Scanners.

Option C: FedEx Certified Driver (If You Ship FedEx)

1. Download the FedEx Certified Driver v4.7.0.
2. Extract the ZIP file and run the installer inside.
3. Follow the prompts — this installs a driver specifically tuned for FedEx 4×6 labels.

Verify Installation

1. Open Settings > Devices > Printers & Scanners (Windows 10/11).
2. Look for ZDesigner GK420d (or “UPS Thermal” if you used the UPS driver).
3. Right-click → Printer Properties → Print Test Page.

Success! If a readable test page prints, your GK420d is ready. Continue to your shipping platform’s setup — see our guides for UPS.com / WorldShip, FedEx Ship Manager, or FedEx.com.

Printing a Test Page

You can also print a configuration label directly from the printer itself (no computer needed):

1. Make sure the printer is on and the green light is steady.
2. Press and hold the Feed button for about 3 seconds, then release.
3. The printer outputs a configuration label with all current settings — firmware version, print speed, darkness, sensor type, and communication settings.

This label is useful for confirming the printer is functional and for troubleshooting.

Calibrating the Printer

If the printer feeds multiple labels without stopping, or prints in the wrong position, you need to calibrate the media sensor.

Manual Calibration (Feed Button Method)

1. Turn the printer off.
2. Press and hold the Feed button.
3. While holding Feed, turn the printer on.
4. Continue holding Feed until the green status light comes on (about 10 seconds).
5. Release the Feed button.
6. The printer feeds several labels while it learns the label gap, then stops.
7. Press Feed once more — the printer should advance exactly one label.

Still feeding multiple labels? Make sure you’re using labels with gaps between them (not continuous stock). The GK420d’s transmissive sensor looks for the gap between labels to know where to stop. If you’re using black-mark labels, you’ll need to switch the sensor mode — check the GK420d User Guide for instructions.

Troubleshooting

Resources & Official Links

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