How to Convert MBR to GPT in Windows Without Data Loss

Introduction

When setting up a new hard drive or reinstalling Windows, you’re often asked whether you want to use MBR (Master Boot Record) or GPT (GUID Partition Table).

Most modern systems use UEFI firmware, which requires GPT instead of MBR. But what if your disk is already formatted as MBR and contains important data?

Good news — you can convert MBR to GPT in Windows without losing data, safely and efficiently.

In this article, we’ll explain:

• The difference between MBR and GPT,
• Why you should convert to GPT,
• And step-by-step methods to perform the conversion without formatting your disk.

What Are MBR and GPT?

Before converting, it’s essential to understand the basics.

🔹 MBR (Master Boot Record)

• The older partitioning style, introduced in the 1980s.
• Stores boot information in the first sector of the disk.
• Supports only 4 primary partitions.
• Maximum disk size: 2 TB.
• Works with Legacy BIOS systems.

🔹 GPT (GUID Partition Table)

• The modern partitioning style, used with UEFI firmware.
• Supports up to 128 partitions on Windows.
• Can handle disks larger than 2 TB.
• Stores redundant partition tables for recovery.
• More secure and reliable.

Why Convert MBR to GPT?

Here are the main reasons to switch from MBR to GPT:

👉 Windows 11 specifically requires UEFI with Secure Boot, which means GPT is mandatory for installation.

Precautions Before Conversion

To ensure a safe conversion process without losing data, follow these precautions:

1. Backup Important Data
   Even though MBR-to-GPT conversion can be lossless, creating a full backup of your important files is essential.
2. Check System Compatibility
   Make sure your system supports UEFI boot mode.
   • Enter BIOS setup (usually F2, Del, or Esc during startup).
   • Look for “Boot Mode” — it should list UEFI.
3. Close All Programs
   Before running conversion commands, close all applications and background tasks.
4. Ensure Sufficient Power
   If converting a laptop, keep it connected to power during the entire process.

Method 1: Convert MBR to GPT Using MBR2GPT (Without Data Loss)

Windows 10 and Windows 11 include a built-in utility called MBR2GPT, which can convert disks without deleting data or partitions.

🔹 Step 1: Check Current Partition Style

1. Press Windows + X → Select Disk Management.
2. Right-click on your disk (e.g., Disk 0) → Properties → Volumes tab.
3. Look for Partition Style — if it says “MBR,” you can proceed.

🔹 Step 2: Open Command Prompt as Administrator

1. Press Start, type cmd.
2. Right-click Command Prompt → Select Run as administrator.

🔹 Step 3: Validate the Disk

Before converting, verify the disk structure:

mbr2gpt /validate /disk:0 /allowfullos

• Replace 0 with the correct disk number from Disk Management.
• If validation succeeds, proceed to conversion.

🔹 Step 4: Convert the Disk

Run the conversion command:

mbr2gpt /convert /disk:0 /allowfullos

✅ What this does:

• Creates a GPT partition table.
• Updates boot files for UEFI mode.
• Preserves existing data and partitions.

🔹 Step 5: Change BIOS Settings

After successful conversion:

1. Restart your computer.
2. Enter BIOS (press Del, F2, or Esc).
3. Change Boot Mode → Set to UEFI.
4. Save and Exit.

Your system will now boot using UEFI with GPT.

Method 2: Convert Using Disk Management (Data Loss Warning)

If you don’t mind erasing all data, you can use Disk Management to reformat the drive.

⚠️ Warning: This method erases all partitions and data on the disk.

Steps:

1. Right-click This PC → Manage → Disk Management.
2. Right-click the disk → Delete all volumes.
3. After it becomes unallocated space, right-click → Convert to GPT Disk.

Use this only for empty or new disks.

Method 3: Convert MBR to GPT Using Third-Party Tools

If the built-in tool fails, you can use reliable third-party utilities.
These tools offer GUI interfaces and often ensure zero data loss.

Recommended Tools:

• EaseUS Partition Master
• AOMEI Partition Assistant
• MiniTool Partition Wizard

General Steps:

1. Install the tool and select your MBR disk.
2. Choose Convert MBR to GPT.
3. Apply and confirm changes.
4. Restart system if required.

These tools perform automatic validation and usually don’t require BIOS changes manually.

Verify Conversion

After conversion, confirm the new partition style:

On Windows:

1. Press Windows + X → Disk Management.
2. Right-click disk → Properties → Volumes.
3. You should see: GUID Partition Table (GPT).

Or use Command Prompt:

diskpart
list disk

GPT disks show an asterisk (*) under the GPT column.

Troubleshooting Common Issues

Benefits of Converting to GPT

By switching to GPT, you ensure future compatibility, better performance, and enhanced reliability for modern hardware and OS versions.

Final Verdict

If you’re using Windows 10 or 11 and have UEFI firmware, converting your system disk from MBR to GPT is highly recommended.

Using the MBR2GPT tool, you can do it without losing any data, ensuring a smooth transition to modern standards.

✅ Recommended method:
Run:

mbr2gpt /convert /disk:0 /allowfullos

Then switch BIOS mode to UEFI — and your system is ready for the future.