Help me choose

Suppose one word is 5 characters,

With 59 USD, if you use GT4T to translate roughly over 650 words daily in average for the next 12 months, the 12 months package may be a better choice, otherwise choose 1200k. (1200000/5/365=657)

With 39 USD, if you use GT4T to translate roughly over 770 words daily in average for the next 6 months, the 6 months package may be a better choice, otherwise choose 700k. (700000/5/182=770)

With 9 USD, if you use GT4T to translate roughly over 1000 words daily in average for the next 30 days, the 1 months package may be a better choice, otherwise choose 150k. (150000/5/30=1000)