On the pro side, charging by the word, especially by the source word, means that everyone knows in advance how much the translation will cost. A 10,000 word translation at 20 cents per word will cost exactly $2,000, no matter how long it takes the translator to complete it. Charging by the word is also an advantage for experienced translators and those who keep up with advances in translation productivity software, since translators who work faster make more money. Finally, charging by the word leaves very little room for debate or interpretation about what work is billable and what work is not; the translator simply issues an invoice for the number of words translated (just make sure to always agree in advance on whether you will bill for the source or target word count).