The filter thread size of Fujifilm XF 100-400mm F4.5-5.6 R LM OIS WR is 77mm.
Below are links to the filters that we recommend you to consider for your Fujifilm XF 100-400mm F4.5-5.6:
Read our detailed Fujifilm XF 100-400mm F4.5-5.6 R LM OIS WR Review