The filter thread size of Panasonic Leica DG Vario-Elmarit 8-18mm F2.8-4.0 ASPH is 67mm.
Below are links to the filters that we recommend you to consider for your Panasonic 8-18mm F2.8-4.0 ASPH:
Read our detailed Panasonic Leica DG Vario-Elmarit 8-18mm F2.8-4.0 ASPH Review