Moisture Barrier Requirement Calculator

Work out moisture barrier requirement instantly with clear inputs, formula shown and shareable results.

About Moisture Barrier Requirement Calculator

The barrier requirement follows from the moisture budget: allowable water gain divided by shelf life days gives grams per day, and dividing by pack surface area gives the maximum water vapour transmission rate the laminate may have. WVTR is quoted at a stated temperature and humidity, so the specification must state those conditions.

Formula

Barrier requirement

Water allowed = product weight x allowable gain %; max WVTR = water allowed / (days x pack area)

Worked example

With the default values below, Moisture Barrier Requirement Calculator returns Maximum Permissible WVTR of 0.11416. Change any input above and every figure here is recalculated in your browser.

Inputs used

Product Weight Per Packminimum 0.01 g: 250 g
Allowable Moisture Gainaccepts 0.001–20 %: 1 %
Required Shelf Lifeminimum 0.01 days: 365 days
Pack Surface Areaminimum 0 m2: 0.06 m2

Results

Maximum Permissible WVTR: 0.11416
Total Water Ingress Allowed: 2.5000
Water Ingress Per Day: 0.006849
Shelf Life: 12.01

Step by step

1Values used
2Barrier requirement
3Maximum Permissible WVTR= 0.11416
4Total Water Ingress Allowed= 2.5000
5Water Ingress Per Day= 0.006849
6Shelf Life= 12.01

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 6 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

What WVTR do common materials give?

Around 5-15 g/m2/day for PE at 38 C and 90% RH, 1-5 for metallised film, 0.1-0.5 for high-barrier coated films and effectively zero for aluminium foil above 9 micron.

Do seals and closures matter?

Often more than the film. A pack with excellent film but a poor seal or a leaking closure fails long before the barrier calculation predicts, so integrity testing is essential.