With Gparted I have to guess the new size of the partition. If I put the size according to free space, Gparted allows me to put new values, but outputs an error after starting the operation: resize2fs: New size smaller than minimum (2277127). If it can't use that values, why it can't analyze the partition, and don't allow me to put them? Should I use some other programs? How Raspbian release images are made?
So, there is around 1,6Gb of free space on partition, which I can't shrink. I changed partition size long time ago but didn't faced such problem (may be because it was fa32 and ext2, or I didn't shrink it enough).