Converting a Data SSD or SSD with Windows® Installation from Legacy to UEFI without Data Loss

Documentation

Install & Setup

000024558

01/31/2019

Note
  • Before proceeding, we recommend backing up all data.
  • Links provided to third-party tools and sites are for your convenience. We don't endorse the content, products, or services offered. We don't offer support for third-party tools.

This article describes methods to convert SSDs from MBR to GPT partition structure. If you have the legacy boot option set in the BIOS (Basic Input/Output System), it's possible the drive partition table is Master Boot Record (MBR).

If the drive is a secondary/data drive (no OS installed), you can use third-party applications such as EaseUS® to convert from MBR to GPT.

  1. Confirm the drive is MBR or GPT:
    • Open Disk Management by pressing Windows key + R > select Disk Management. Right Click on left panel for the Disk being checked (for example Disk 0, Disk 1, etc) > Properties > Volumes.
  2. If MBR, convert to GPT:

If you are accelerating the system disk (OS Installed) proceed with details below.

You might have the legacy boot option set in the BIOS:

  • After upgrading to Windows® 10 from an older operating system (OS) version, such as Windows® 7 or Windows® 8.1.
  • If you recently installed the operating system, setting the legacy boot option in the BIOS.
  • If you recently installed the operating system and the BIOS was set to CSM, setting the legacy boot option in the legacy boot media partition.

MBR vs. GPT Installation

You may lose some support with the MBR partition table on Windows® 10, such as system acceleration with Intel® Optane™ memory.

The Windows 10 operating system was designed to install with the UEFI (Unified Extensible Firmware Interface) boot option and the resulting drive partition table GUID Partition Table (GPT).

If you want to convert your current partition table from MBR to GPT, we recommend you:

  • Safely back up all your data.
  • Reinstall your operating system from a UEFI OS image with UEFI enabled in the BIOS.

With Windows® 10 Creators Update x64 (Version 1703, Build 10.0.15063) or later, there's an option to convert the partition table from within Windows®. See the steps for this option below.

Note
  • We highly recommended performing a backup of your data. If you have a second disk drive with enough available capacity, you can create a system image and recover the full installation as it was before you started this procedure.
  • Download these steps to another computer or print them out. Some of these steps need to be performed while your OS isn't active.
  • Create a backup of your recovery partition on a USB device. Once created, this bootable recovery USB can optionally be substituted for the system repair disc in the steps below.

Confirm that Windows is installed to an MBR partition

  1. Boot into Windows®.
  2. Open Disk Manager. For Windows 10, press the Windows key and the X key simultaneously, then click Disk Manager.
  3. Locate your primary system boot partition.
    Locate your primary system boot partition
  4. Right-click the disk shown as (Disk x, Basic, Capacity, Online) on the left (Where it says Disk 0 as example in this image).
  5. Select Properties.
  6. Click the Volumes tab.
  7. Here you can confirm the Partition style.

Convert partition table from MBR to GPT with MBR2GPT.exe

Requirements:

  • Windows® 10 Creators Update x64 (Version 1703, Build 10.0.15063) or later.
  • A computer able to boot UEFI. In the BIOS setup, you should see options for UEFI boot. Confirm with your computer manufacturer for support.

Instructions:

  1. Open Command Prompt with administrator privileges.
  2. Issue the following command: mbr2gpt.exe /convert /allowfullOS.
  3. Shut down and boot into your BIOS.
  4. Change your settings to UEFI mode.

Alternatively, you may run this command from within the recovery environment:

  1. Boot to the Windows* Recovery Environment and start the Command Prompt console:
    • Press the Windows key and I key simultaneously to open Settings.
    • Select Update & Security.
    • Select Recovery.
    • Select Restart now under Advanced startup.
    • Select Troubleshoot.
    • Select Advanced Options.
    • Select Command Prompt.
    • It may prompt you to select a user account and type in a password.
  2. Issue convert command: mbr2gpt.exe /convert.
  3. Restart your computer and boot into your UEFI BIOS.
  4. Change BIOS setting from Legacy to UEFI mode.
Related topics
How to Install Windows® 10 to a GUID Partition Table (GPT) Partition
Using MBR2GPT.EXE to convert a disk from MBR to the GPT