How can I change mbr to gpt without data loss?

You're thinking about changing from MBR to GPT without losing data — nice move, but gotta be careful. Don’t just jump in with any partition tool. Use reliable ones like Disk Management (built-in), or third-party tools. Some tools are buggy or buggy enough to cause data loss. Make sure your motherboard and BIOS support GPT (most modern stuff does, but older BIOS systems might not). If your BIOS is BIOS instead of UEFI, switching to GPT might cause boot issues.

If it’s your boot drive (where Windows is installed), you need to do a GPT conversion in UEFI mode. Doing it in Legacy BIOS mode can brick your OS. Also, for a system disk, use tools like Microsoft’s MBR2GPT utility — don’t just try to convert with third-party tools blindly. After changing MBR to GPT without losing data, make sure to switch your BIOS from Legacy to UEFI mode if needed. If you forget, your system won’t boot.

Your disk should be partitioned properly after conversion. For example, if you have multiple partitions, make sure they’re all intact and correctly formatted. Every tool has its quirks. Read the documentation. For example, MBR2GPT has specific steps and requirements, like having a system partition with enough space, no other OS installed on the same disk, etc.