Normally the acurrate calculation for requirement of the Desiccant is difficult, because of the various factors like climatic conditions, hygroscopicity of stuffing goods, Transit duration, climatic and temperature variations while sailing in sea etc. But normally we recommend 2 - 4 kgs for a 20 foot Container Dry Cargo with Moisture content of the goods less than 10% and transit time 10 Days. If moisture content is more than 10 % we recommend 4- 6 kgs. You can also increase or decrease of the quantity of desiccants as per your needs. Using more number of desiccants will give a good protection from condensation.