How to Change Legacy to UEFI Without Reinstalling Windows 10

Last updated on February 28th, 2019

On the latest motherboard (PC/Laptops) models, the manufacturers have added the support for the UEFI (Unified Extensible Firmware Interface), in addition to the traditional BIOS (Basic Input Output System) firmware interface. This is happened, because the UEFI can support hard disks with over 2TB storage disk space and offers better performance, diagnostics and repairs of computers, even with no operating system installed.

UEFI is supported only on 64-bit Windows 7, 8/8.1 or 10 Editions and since the Windows 10 version 1607 you cannot use the UEFI advantages (if your mainboard supports it), without having to reinstall Windows from scratch, because the UEFI uses the GUID Partition table (GPT), instead of the Legacy BIOS which uses the MBR Partition Table.

If you have a computer or laptop, with Windows 10 version 1703 (Build 10.0.15063) or later, you can take advantage of the UEFI without having to reinstall Windows, by using the MBR2GPT.EXE command line tool.

In this tutorial you 'll find detailed instructions to change the Legacy Boot to UEFI Boot, without having to reinstall the operating system and with No Data loss. The instructions applies only if you have installed Windows 10 {version 1703 (Build 10.0.15063)} on your computer.

The tutorial applies to one of the following cases:

  • Your system has upgraded to Windows 10 from an older Operating System (e.g. Windows 7, 8 or 8.1).
  • You have installed the Windows 10 OS v1703 (or later version), using the Legacy boot option in BIOS (CMOS) setup.
  • You have installed the Windows 10, v1703 (or later version), using a Windows 10 boot media created for MBR partition type.

How to Change from Legacy Boot Mode to UEFi Boot Mode without reinstalling and data loss in a Windows 10 PC.

Prerequisites.
1. You own a PC or Laptop with a motherboard that supports both Legacy and UEFI.
2. You own a PC or Laptop with Windows 10 version 1703, 1709 or later, already installed* to an MBR Partition.**

* Note 1: To view the installed Windows 10 version/build:

1. Press the "Windows" image  + "R" keys to load the Run dialog box.
2. Type winver and press Enter.

Change Legacy to UEFI

Change Legacy to UEFI without data loss

** Note 2: To view if Windows 10 is installed to an MBR partition:

1. Press the "Windows" image  + "R" keys to load the Run dialog box.
2. Type diskmgmt.msc and press Enter.

disk management

3. Right click on your main disk (Disk 0) and click Properties.
4. If the "Convert to GPT Disk" option is greyed out, then the partition style on your disk is MBR.

view disk properties

How to use MBR2GPT.EXE tool, to convert MBR partition to GPT, without data loss

Once again: The instructions below apply only if you have already Windows 10 version 1703 or later on your system. If you don't, then navigate to Windows 10 download site and click the Update now button, to install the latest Windows 10 version.

Suggestion: Before you continue to the steps below, backup your data, to avoid data loss if something goes wrong.

Method 1. Convert MBR to GPT from Windows GUI.
Method 2. Convert MBR to GPT Using Recovery Environment.

Method 1. Convert MBR to GPT from Windows GUI.

1. In the Search box type: cmd or command prompt
2. Right click on the command prompt (result) and select Run as Administrator.

command prompt administrator

3. At command prompt, type the following command and press Enter.

  • mbr2gpt.exe /convert /allowfullOS

change mbr to gpt

4. Wait until the conversion is completed.

convert mbr to gpt windows 10

5. When the conversion is done, Shutdown your computer.
6. Power on you computer and enter into BIOS Setup.
7. Change the Boot Mode from Legacy to UEFI.

legacy to uefi

8. Save changes and exit from BIOS Setup.
9. Boot to Windows 10 normally.

Method 2. Convert MBR to GPT Using Recovery Environment.

1. Boot your computer from a Windows Installation Media (USB or DVD). *
2. At the Windows Setup screen press SHIFT + F10 to access command prompt, or choose Next –> Repair your computer –> Troubleshoot –> Advanced Options –> Command Prompt.

* If you don't own a Windows Installation Media, then you can create one (corresponding to your Windows Edition and Version) directly from Microsoft.

windows setup screen

3. In command prompt type the following command and press Enter:

  • mbr2gpt.exe /convert

4. When the conversion is done, Shutdown your computer.
5. Power on you computer and enter into BIOS Setup.
6. Change the Boot Mode from Legacy to UEFI.
7
. Save changes and exit from BIOS Setup.
8. Boot to Windows 10 normally.

That's it! Let me know if this guide has helped you by leaving your comment about your experience. Please like and share this guide to help others.

If this article was useful for you, please consider supporting us by making a donation. Even $1 can a make a huge difference for us in our effort to continue to help others while keeping this site free: