What size filter should I get for my Fujifilm d/slr?

I'm not sure what size filter cap I should get. On the Fuji site it says it has a 28mm wide angle lens. Do I get that size or do I measure from one edge of the lens to the other? (which is 55mm) This is my camera in case you have it, it's a Fujifilm Finepix S1900. http://www.fujifilm.co.uk/consumer/digital/digital-cameras/d-slr-long-zoom/finepix-s1900?qc=auto&q=FinePix%20S1900