ðɪ ɛkspɹˈɛʃən, ˈɔːlweɪz ɡˈɪvən ɪn fˈiːt, ɪz ɐ skˈeɪld fˈɪɡjɚ kˌɔːɹɪspˈɑːndɪŋ tə ɹˈʌfli hˈæf ðɪ ˈæktʃuːəl mˈɛʒɚd ɔːɹ ˈɛstᵻmˌeɪɾᵻd hˈaɪt əvə wˈeɪvz fˈeɪs tɹˈɔf tə kɹˈɛst hˈaɪt.
The expression, always given in feet, is a scaled figure corresponding to roughly half the actual measured or estimated height of a wave's face (trough to  crest height).