This study aims at unveiling phonetic cue weighting of English word recognition by Korean learners of English using a web-based online perception experiment. The longer duration of a high front tense vowel than that of a lax counterpart is used as a cue by native English speakers and presumably as a cue by Korean learners of English. The longer duration of a vowel before voiced stops than that of an equivalent before voiceless stops serves as a cue by native Speakers of English and also probably by Korean learners of English. A web-based online experiment has been designed to examine how Korean learners of English cope with a mixture of fine grained phonetic cues. Results of the web-based online experiment reveal that duration is primarily and robustly used to distinguish a tense vowel before voiced stops and a lax vowel before voiceless stops. At the same time, spectral cues are also put to use, though to a lesser extent, to help make a distinction from a tense vowel before voiceless stops and a lax vowel before voiced stops. The study implies that learners of English try to utilize a complex mixture of acoustic cues to distinguish words.