Changing your BIOS from Legacy to UEFI in Windows 10 is one of those tweaks that sounds more intimidating than it actually is. If you’re tired of slower boot times, limited security features, or just wanna handle larger drives better, switching to UEFI might be the fix. But, of course, before doing anything drastic, you should check if your system supports it — not all motherboards are UEFI ready. Then, it’s all about prepping: backup your important files, because this process often involves a clean install, and creating a Windows 10 installation media with Microsoft’s Media Creation Tool. The tricky part is entering your BIOS—sometimes the key to press is F2, DEL, F12, or ESC, depending on your motherboard—and then finding the right menu to toggle from Legacy to UEFI. Switching the boot mode alone won’t do the trick; you’ll need to reinstall Windows in UEFI mode afterwards for it to work properly. And don’t forget, if you’re using a traditional MBR partition table, you’ll have to convert to GPT, so keep that in mind too — tools like MBR2GPT are handy for that.
How to Fix BIOS Mode from Legacy to UEFI in Windows 10
Check if your system can handle UEFI
This is kind of the first hurdle. Not every PC supports UEFI, especially older ones. You can verify this in your motherboard’s manual or by checking your system specifications online. If you’re not sure whether UEFI is enabled or supported, a quick way is to boot into your current BIOS and look for the *Boot Mode* or *UEFI/Legacy Boot* setting. If it’s missing or only shows Legacy, you might be out of luck or need a firmware update. Also, run msinfo32 in Windows, then look for “BIOS Mode” — if it says UEFI, you’re good to go, otherwise, you’ll need to switch it in the BIOS itself.
Backup everything before you start
This isn’t just paranoia — switching BIOS modes often means wiping your drive for a clean install. Use an external hard drive, cloud storage, or whatever backup method you trust. You don’t want to lose those precious family photos or work files just because of a change that seems simple on paper. Also, note down your current BIOS settings because sometimes, you’ll want to revert if things go sideways.
Create Windows 10 bootable media
Grab a blank USB stick (at least 8GB) and head over to the official Microsoft Media Creation Tool. Run it, select “Create installation media for another PC, ” and pick the correct language plus architecture (likely 64-bit).When it finishes, you’ll have a bootable USB ready to reinstall Windows with the UEFI mode enabled. It’s a lifesaver for this whole switch.
Access your BIOS settings
Reboot and press the key (usually F2, F12, DEL, or ESC) that gets you into BIOS. It’s kinda weird, but sometimes the key flash on the splash screen or your motherboard’s manual has the answer. Once inside, look around for the *Boot* tab or menu. Here’s where it gets interesting—your options for boot mode, boot list, or CSM (Compatibility Support Module).You wanna switch from Legacy or CSM mode to UEFI. Sometimes, you might gotta disable CSM to enable pure UEFI boot, which can be a little confusing if you’re not used to BIOS menus.
Switch to UEFI mode and prep partitions
Change the *Boot Mode* or *Boot Priority* to UEFI. Now, if your drive is formatted with MBR, Windows won’t boot after reinstall unless converted to GPT. Use mbr2gpt.exe /convert /allowfullOS in Command Prompt run as administrator — but only after you’ve backed up everything and confirmed your drive is ready. Quick tip: in some setups, you might have to disable Secure Boot temporarily before switching modes, then re-enable it after the installation.
Reinstall Windows in UEFI mode
Plug in your USB installer, boot from it (which might require selecting your boot device via F12 or F11), and follow the prompts. When you get to the installation screen, make sure to delete your current partitions and select the unallocated space — this ensures Windows installs cleanly in UEFI mode. After completing the setup, your PC should boot up faster with all the benefits UEFI provides: Secure Boot, faster startup, support for bigger drives, and a modern interface.
Fair warning: sometimes, this process doesn’t go perfectly the first time and you might need to tweak a few settings, or update your BIOS firmware (check your motherboard’s website for updates).But once done, the gains are noticeable — fewer boot delays, better security, and future-proofing your PC. Just be prepared for a bit of patience and some troubleshooting if things don’t go as planned. That’s normal.