By Dervish / Last Updated May 12, 2023

What is boot mode Legacy and UEFI?

Boot mode is actually the program that boots the computer to start. Simply put, it is a program that starts first after the computer is turned on and prepares for the startup of the operating system. There are three kinds of boot modes: Legacy BIOS, UEFI, and Legacy + UEFI. Read on, and you’ll know what's the differences between Legacy and UEFI, and how to boot from Legacy or UEFI.

Legacy boot mode

Legacy boot mode, as its name implies, is a kind of traditional boot mode. It is common in Windows systems before Windows 8. It owns good compatibility and can be used on both on 32bit and 64bit systems.

Legacy mode

Legacy boot mode supports MBR disk, whose features are listed as follows:
It supports up to four primary partitions.
It doesn’t support a disk beyond 2 TB.
Only one operating system boot record can be stored in a single MBR.

UEFI boot mode

UEFI, the successor to Legacy, is currently the mainstream boot mode. Compared with Legacy, UEFI has better program ability, greater scalability, higher performance, and higher security. In recent years, UEFI has become an increasingly common boot mode. Microsoft has also made it clear that Windows 11 needs to boot from UEFI.


★UEFI supports GPT disk, which owns the following features:
It supports up to 128 primary partitions.
It breaks disk size limitation of 2 TB and supports up to 18 EB.
UEFI offers secure boot to prevent various from loading when booting.
The interface of UEFI BIOS is more intuitive, and more interactive, and it supports mouse operation and multi-language.
There is no self-test process at boot time, and the boot speed can be faster.

Legacy+UEFI boot mode

Legacy mode is old but not completely useless, as some hardware (like GTX660) and systems (like XP) only support Legacy mode.

Legacy And Uefi

Therefore, most new motherboards also allow users to switch to Legacy+UEFI compatibility mode. When the BIOS detects a system installed under Legacy, it will start the Legacy boot mode. Similarly, if it detects a system installed under UEFI, It will start in UEFI mode.

How to check out boot mode

If you are not sure which boot mode your PC is using, you can use the following methods to check whether your computer is using Legacy BIOS or UEFI.

Step 1. Press "Windows + R", type in "msinfo32" and hit Enter to open system information.

Step 2. Now, you can check the boot mode of the PC.

Check Boot Mode

Should I boot from Legacy or UEFI?

For Windows 11 users, you must boot from UEFI, as Microsoft requires Windows 11 to be booted from UEFI boot mode. So, if your system disk is MBR partition style, you have to convert it to GPT, and then change the Legacy boot mode to UEFI. Please refer to the following steps:

▶ Part 1. Convert MBR to GPT

As mentioned earlier, Legacy BIOS supports MBR disk, while UEFI supports GPT disk. If you plan to boot your PC via UEFI, then you need to check if your system disk is a GPT disk. If not, you should convert MBR to GPT.

To convert MBR to GPT quickly and easily, I recommend you to use AOMEI Partition Assistant Professional. This is a powerful MBR to GPT converter in Windows 11, 10, 8, 7, Vista and XP, it supports to convert both data disk and system disk from MBR to GPT without data loss.

Warning: Make sure that your motherboard supports UEFI before converting the system disk to GPT. Otherwise, the PC will not boot normally. 

Please download the demo version of AOMEI Partition Assistant Professional to see how to boot from Legacy or UEFI. 

Download Demo Win 11/10/8.1/8/7/XP
Secure Download

Step 1. Install and run AOMEI Partition Assistant Professional. In the main Tab, click the target disk and then select Convert to GPT on the right pane.

Convert System Disk To Gpt

Tip: If your disk is originally initialized as GPT, you can choose Convert to MBR Disk without losing data.

Step 2. Click OK and Yes to confirm your operation.

Ok To Gpt System Disk

Step 3. You’ll get back to the main interface. Click Apply and Proceed to commit the operation.

Apply To Gpt System Disk

▶ Part 2. Change Legacy to UEFI

After convert system disk from MBR to GPT, your computer will restart. The PC will not boot without changing the boot mode from Legacy BIOS to UEFI.

1. Press the prompt key at the bottom of the screen continuously to enter the BIOS setup menu when powering on.

2. In the BIOS Setup Utility, navigate to the Boot tab on the top menu bar.

3. The boot menu screen appears. Select the UEFI/BIOS Boot Mode field and use the "+/-" keys to change the setting to UEFI.

4. Save and exit. Reboot again and your computer will boot from UEFI.

Change Legacy to UEFI

Wrap things up

From what has been discussed above, we had talked about the difference between Legacy BIOS and UEFI. In addition, the specific steps of changing BIOS to UEFI were provided too, I believe you have an answer about how to boot from Legacy or UEFI. 

Last but not least, if you need to convert MBR to GPT in Windows Server, you need to switch to AOMEI Partition Assistant Server.