How to Determine Desiccant Requirements

(For Hermetically Sealed Barrier Containers)


Approximate Required Weight in Grams of Desiccant = 170 x (V x .02832) + (D x 453.6) x F


V = The volume in cubic feet of air inside the barrier
D = The weight in pounds of any dunnage within the barrier
F = Dunnage factor:
= 1/5 for timber with moisture content higher than 14%
= 1/8 for felt, carton board and general packaging materials
= 1/10 for plywood or timber with moisture content less than 14%

Please Note:

This formula is based on the use of silica gel – if using clay desiccants add approximately 30% to the weight (multiply by 1.3)


It is difficult to determine the exact amounts of desiccant required from the above formula given the many variables that can influence the effect of the desiccant. This formula is intended for use as a guideline only in determining approximate amounts. Use of this formula does not guarantee any results due to the many variables that may apply.

Additional Variables:

  • Condensation of water vapor will not occur, even at 90% relative humidity, as long as the temperature does not change
  • Daytime and nighttime temperature changes
  • Seasonal temperature changes
  • Temperature changes affected by machinery running in close proximity
  • MVTR of packaging material used
  • Duration of time in use