Safe way to convert mbr to gpt without formatting on windows 10?

Typical scenarios where a mrb to gpt conversion makes sense

Installing Windows 11 on a PC that shipped with Windows 10 in Legacy BIOS mode.

Migrating your OS to a new NVMe SSD larger than 2 TB.

Setting up multi-boot (Windows + Linux + recovery) without resorting to extended partitions.

Enabling BitLocker with TPM 2.0 + Secure Boot for stronger full-disk encryption.

Checklist before mbr to gpt conversion

1. Back up anything you care about. A typo or power loss can still brick the disk.

2. Make sure the disk meets GPT rules:

First partition starts at or after sector 34

At least 33 free sectors at the very end (GPT keeps its backup header here)

3. Firmware must be able to boot UEFI. If you’re converting a system disk, switch the motherboard from Legacy/CSM to UEFI after the conversion but before first boot.

4. If the drive will become bootable, have Windows installation media handy so you can run bcdboot to create an EFI System Partition (GPTGen does not do that part for you).