How to Flash LG Firmware with LG Flash Tool

Q: Will flashing LG firmware erase my data?

Yes — flashing stock firmware wipes all user data. Always back up before flashing.

Q: My LG phone won't turn on — can I flash it?

If your phone can enter download mode (hold Volume Down + Power), you can use LG Flash Tool to reflash the firmware and recover it.

Q: Which firmware file format does LG Flash Tool use?

LG Flash Tool uses .KDZ files. If you have a newer LG device (2017+), use LGUP Tool instead, which handles .TOT files.

Q: Do I need to install USB drivers first?

Yes — install LG USB drivers before connecting your phone. Without them, the tool cannot detect your device.

By Daniel Cross — Android Firmware Specialist | Updated April 2025

To flash LG firmware: install LG USB drivers, download LG Flash Tool, boot your phone into download mode, connect via USB, load your KDZ firmware file, and click Start. The process takes 10–20 minutes. Works on Windows 7 through Windows 11. Full steps below.

LG Flash Tool gives you a complete flashing experience, providing access to the full potential of your LG device. It is a lightweight application for flashing stock firmware on LG smartphones and tablets, supporting the official .KDZ and .TOT firmware formats from LG. You can install, upgrade, downgrade, or completely restore the official firmware of any LG device using this tool on Windows.

Downgrade or upgrade the firmware of your LG device with ease. Compatible with almost all versions of Windows OS including Windows 7 through Windows 11 (32-bit and 64-bit). For newer LG devices using TOT firmware, see our LGUP Tool page.

Why Should You Flash LG Devices with LG Flash Tool?

Portable Application

Since it was developed as a portable application, LG Flash Tool does not require complex installation on your PC to use. You only need to install the LG USB Driver on your PC. Then connect your LG device, open the Flash Tool, load the firmware, and begin the process immediately.

Flash Firmware Directly

Flash .KDZ and .CAB stock firmware onto your LG phone, tablet, or feature phone. Install the compatible stock firmware for your specific device using the LG USB driver to establish the connection and LG Flash Tool to perform the flash operation.

Multiple Chipset Support

You can flash the stock firmware on LG devices running various chipsets, including CDMA Smartphone (WM), CDMA, ADI, 3GQCT, 3GQCT Smartphone (WM), EMP, Infineon, ODM MediaTek, MediaTek (IM, BIN), and ODM Smartphone variants. This broad chipset support makes LG Flash Tool the most versatile option for LG firmware management.

Device Information Reading

LG Flash Tool can read detailed information about your LG smartphone including Model Name, ESN/IMEI Number, Phone Software Version, Phone Number, Battery Level, Chip Type, Smartphone Model, Android Version, and LTE DL Mode status. This is useful for identifying the exact firmware variant you need to download.

Requirements Before Flashing

Before continuing with the flashing process, review these requirements carefully to prevent bricking your device:

Check that battery percentage is at least 70%. A low battery during flashing can cause an incomplete flash and brick the device.
Keep a full backup of your device — flashing will erase user data in most cases.
Activate USB debugging mode. Navigate to Settings > About Phone > Build Number and tap it about seven times to enable Developer Options. Then go to Settings > Developer Options and enable USB Debugging.
Have the correct KDZ or TOT firmware file downloaded for your exact device model and region before starting.
LG USB drivers must be installed on the PC before connecting the phone.

How to Flash LG Firmware — Step by Step

This guide covers flashing stock firmware using LG Flash Tool on a Windows PC. For LGUP flashing instructions, see our LGUP Tool page. If you encounter errors during this process, refer to our troubleshooting guide.

Download and install the latest version of LG USB driver software on your Windows PC. Do not skip this step — the tool will not detect your device without the correct drivers.
Download LG Flash Tool from our download page. Extract the compressed zip file and run the installer executable as Administrator.
Power off your LG smartphone completely. Boot into download mode using the button combination for your model — commonly: Power off, then hold Volume Down while connecting the USB cable, or hold Power + Volume Up on some models.
Connect the download-mode device to your PC using a recommended USB data cable. Use a USB 2.0 port if available — USB 3.0 can cause connection issues with some LG models.
Open LG Flash Tool. Click on the "Select KDZ File" area and navigate to the KDZ firmware file you downloaded for your device.
Choose your flash mode: Normal Flash — replaces the stock firmware while preserving user data. CSE Flash — wipes all data from the device and restores only the boot files; use this for serious corruption or when Normal Flash fails.
Click the Start button and fill in any required details on the next form. Continue the process and wait for it to complete. Do not disconnect the device or close the tool.
Once the entire flashing process is finished, LG Flash Tool will notify you with a completion message. Your device will restart automatically with the new firmware installed.

Note: Keep the downloaded KDZ file in the extracted folder of the tool, or save it in an easily accessible location such as the desktop. The tool needs to locate the file to begin flashing.

Supported LG Chipsets

LG Flash Tool supports flashing on LG devices across a wide range of chipset platforms. Use this table to confirm your device is supported:

Chipset Platform	Type	Tool
Qualcomm Snapdragon (pre-2017)	CDMA / LTE	LG Flash Tool
Qualcomm Snapdragon (2017+)	LTE	LGUP Tool
MediaTek (IM, BIN)	ODM MediaTek	LG Flash Tool
Infineon	3G/LTE	LG Flash Tool
CDMA Smartphone (WM)	CDMA	LG Flash Tool
3GQCT / 3GQCT Smartphone (WM)	3G	LG Flash Tool
EMP / ADI	Feature Phone	LG Flash Tool
ODM Smartphone	Various	LG Flash Tool

Safety Notes for LG Flash Tool Users

Since you are dealing with system-level modifications, careful attention to the instructions below will help ensure a safe and successful flash:

OS Compatibility: LG Flash Tool supports Windows XP, Vista, 7, 8, 8.1, and Windows 10/11 (both 32-bit and 64-bit).
Use the latest version: Always download the latest LG Flash Tool from our download page to ensure maximum device compatibility.
Correct firmware: Download the KDZ file specifically matched to your device model number and carrier variant. Using the wrong KDZ can cause a permanent brick.
Update LG USB Drivers: Always use the latest official LG USB driver. Outdated drivers are a common cause of device recognition failures.

Frequently Asked Questions about KDZ Files

What is a KDZ file? KDZ is the stock firmware format that LG uses for official firmware releases. All official stock firmware for LG Android devices (pre-2017) is distributed in KDZ format. LG Flash Tool is the primary tool for flashing these files.

Is LG Flash Tool safe to download? Yes. LG Flash Tool is the established, widely-used flashing utility for LG devices. Downloaded from a reputable source like lgflash.com, it is safe to use. The tool guarantees speed and consistent performance throughout the flashing process.

What causes the 4% installing error? This is a frequent error during LG Flash Tool installation and is typically caused by unsupported or missing .DLL files in the installation folder. Ensure the MegaLock.dll file is present and install the Visual C++ runtime if the error persists.

How to fix LG Flash Tool connection failure? This is usually caused by driver or USB port issues. Try: reinstalling USB drivers, switching to a different USB port (try USB 2.0 instead of 3.0), running the app as Administrator, and confirming the KDZ file is compatible with your exact device build number.

Is LG Flash Tool free? Yes. LG Flash Tool is completely free to download and use. There are no hidden fees or registration requirements. Downloading from lgflash.com costs nothing.

Frequently Asked Questions

Will flashing LG firmware erase my data?

Yes — flashing stock firmware wipes all user data. The extent depends on the flash mode: Normal Flash replaces the firmware but may preserve data on some devices, while CSE Flash wipes the entire device. Always back up your photos, contacts, and app data before flashing.

My LG phone won't turn on — can I flash it?

If your phone can still enter download mode (typically by holding Volume Down while connecting the USB cable), you can use LG Flash Tool to reflash the firmware and recover it from a bootloop or soft brick. If the device cannot enter download mode at all, you may need professional hardware repair.

Which firmware file format does LG Flash Tool use?

LG Flash Tool uses .KDZ files, which is LG's official firmware format for devices released through 2016. If you have a newer LG device (2017 or later), use LGUP Tool instead, which handles .TOT files used by newer LG models.

Do I need to install USB drivers first?

Yes — install LG USB drivers before connecting your phone to the PC. Without the correct drivers, Windows cannot recognize your LG device in download mode and the flashing tool will report a connection error.