Moisture Ratio Calculator - Calculator Academy

Calculate moisture ratio, drying time, wet-basis/dry-basis conversions, and wood equilibrium moisture content from temperature and RH.

Moisture Ratio Formula

The following formula uses dry-basis moisture contents. Wet-basis inputs are converted to dry basis before applying the ratio.

MR = (Mₜ - Mₑ) / (M₀ - Mₑ)

Variables:

MR is the moisture ratio
M_t is the moisture content at time t
M_e is the equilibrium moisture content
M_0 is the initial moisture content

To calculate the moisture ratio, subtract the equilibrium moisture content from the moisture content at time t. Divide the result by the difference between the initial moisture content and the equilibrium moisture content.

What is a Moisture Ratio?

The moisture ratio is a dimensionless quantity that represents the relative amount of moisture in a material compared to its initial and equilibrium moisture contents. It is commonly used in drying and moisture analysis to understand how much moisture remains in a material over time. The moisture ratio helps in evaluating the drying process and the efficiency of moisture removal from materials such as food, wood, and other hygroscopic substances.

How to Calculate Moisture Ratio?

The following steps outline how to calculate the Moisture Ratio.

First, determine the moisture content at time t (M_t).
Next, determine the equilibrium moisture content (M_e).
Next, determine the initial moisture content (M_0).
Finally, use dry-basis values in MR = (M_t - M_e) / (M_0 - M_e), or let the calculator convert consistently labeled wet-basis values.
After inserting the values and calculating the result, check your answer with the calculator above.

Example Problem :

Use the following variables as an example problem to test your knowledge.

Moisture content at time t (M_t) = 0.5 on a dry basis

Equilibrium moisture content (M_e) = 0.1 on a dry basis

Initial moisture content (M_0) = 0.8 on a dry basis; MR = (0.5 − 0.1)/(0.8 − 0.1) ≈ 0.571429.