How can I safely shrink an encrypted Linux drive for a Windows installation?

If you cannot make and test a full backup, the safer choices are installing Windows on another SSD or using a separate external drive. Windows setup can also overwrite or alter boot entries, so keep a Linux live USB available for boot repair afterward. With a single drive and no reliable backup, repartitioning an encrypted system is a high-risk operation even when the commands are technically correct.

First identify the layout from a live environment with commands such as `lsblk -f`, `cryptsetup luksDump`, `pvs`, `vgs`, and `lvs`. Pop!_OS commonly uses LUKS with LVM, but you should confirm rather than assume. After unlocking it, the general sequence is: check and shrink the filesystem, reduce the logical volume, move any allocated data toward the beginning of the physical volume, reduce the physical volume, close the encrypted volume, and only then shrink the outer partition. Do not resize the outer partition first, and do not rely on a guessed size.

Back up everything important before attempting this. Shrinking an encrypted installation is possible, but GParted usually cannot safely resize a locked LUKS container. You generally have to boot from a live USB, unlock the LUKS volume, shrink the filesystem first, then shrink the logical volume or physical volume, the LUKS container, and finally the partition. The order matters, and one incorrect size can make the installation unbootable. If the files are important, making a complete backup or disk image first is strongly recommended.