The height of existing lighthouses is expressed in two measures: the height of the tower itself, and the distance from the focal plane (that is, the center) of the light source to the water.
ðə hˈaɪt ʌv ɛɡzˈɪstɪŋ lˈaɪthaʊsᵻz ɪz ɛkspɹˈɛst ɪn tˈuː mˈɛʒɚz: ðə hˈaɪt ʌvðə tˈaʊɚɹ ɪtsˈɛlf, ænd ðə dˈɪstəns fɹʌmðə fˈoʊkəl plˈeɪn ðæt ˈɪz, ðə sˈɛntɚ ʌvðə lˈaɪt sˈoːɹs tə ðə wˈɔːɾɚ.