Transferred file 6 times larger than original.

Using Mac OS, copied 54GB iphoto .photoibrary from external HD to brand new Extreme Portable SSD 500GB and final result is over 300GB. 54GB iphoto photolibrary is same size (consistently 54GB) on multiple other external harddrives. Only Scandisk balloons file.

“Get Info” on folder is endless cycle of “calculating size” but DaisyDisk quickly reveals ultimate size.

Any suggestions for how to retain original photolibrary size?

the ssd is just a storage drive and cannot change the file size. It sounds like the transfer is somehow making duplicate copies. You should be able to test by copying other files and check the file size to see if it is changed and if duplicates are being created. 

can you try to format the drive to HFS+ and see if the issue goes away ?