File Path Length Excel

Try

=MID(CELL("filename"),SEARCH("[",CELL("filename"))+1, SEARCH("]",CELL("filename"))-SEARCH("[",CELL("filename"))-1)

For file name and

=LEN(MID(CELL("filename"),SEARCH("[",CELL("filename"))+1, SEARCH("]",CELL("filename"))-SEARCH("[",CELL("filename"))-1))

For its length