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Calcimator

Paper Moisture Calculator

Calculate paper moisture content from wet/dry weights. Estimate dimensional stability impact, equilibrium moisture, and strength changes.

Inputs

%
%

Results

Moisture content (%)

6

Water weight (g)6
Oven-dry weight (g)94
Target wet weight (g)100
Water change needed (g)0
EMC at room RH (%)0.83
Dimensional change (%)0
Strength impact (%)-0
How to Use This Calculator
  1. Weigh your paper sample as-received and record the Wet Weight (g).
  2. Oven-dry at 105°C until constant weight, then enter the Oven-Dry Weight (g).
  3. Enter your target moisture (%) and current room relative humidity (%).
  4. Review Moisture Content (%), Water Weight, and Target Wet Weight.
  5. Use EMC at Room RH and Dimensional Change (%) to plan pressroom conditioning.

What each input means

Wet weight (g)
Weight of the paper sample as received (grams).
Oven-dry weight (g)
Weight after oven drying at 105°C until constant weight (grams).
Target moisture (%)
Desired moisture content percentage (typical 4-8% for printing papers).
Room RH (%)
Relative humidity of the storage/pressroom environment.

What each result means

Moisture content (%)
Current moisture content as percentage of total weight.
Water weight (g)
Weight of water in the sample.
Oven-dry weight (g)
Bone-dry fiber weight.
Target wet weight (g)
What the sample should weigh at target moisture.
Water change needed (g)
Water to add (positive) or remove (negative) to reach target.
EMC at room RH (%)
Equilibrium moisture content the paper will reach in current environment.
Dimensional change (%)
Estimated cross-grain dimensional change from current to target moisture.
Strength impact (%)
Estimated tensile strength change vs. optimum moisture (negative = weaker).

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Wet weight (g) = 100, Oven-dry weight (g) = 94, Target moisture (%) = 6, Room RH (%) = 50 = 4 input(s) provided
  2. Calculate Moisture content
    Moisture content = (waterWeight / wetWeight) * 100
    6 = 6
  3. Calculate Water weight
    Water weight = wetWeight - dryWeight
    6 = 6
  4. Calculate Oven-dry weight
    Oven-dry weight = wetWeight * (1 - moistureContentPct / 100)
    94 = 94

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