Estimate resulting dry coating thickness from wet film thickness and volume solids, with automatic conversion between micrometres, millimetres and mils.
Coating Inputs
The basic estimate uses DFT = WFT × volume solids fraction. This assumes the wet film measurement and volume-solids value are representative of the applied coating.
Ready to calculate. Press Calculate Dry Film Thickness.
Dry Film Thickness Result
Estimated Dry Film Thickness
—
Wet Film
—
input thickness
Volume Solids
—
percent
Dry Film
—
µm
Dry Film
—
mils
Dry Film
—
mm
Wet Film to Dry Film Visualization
Resulting dry film
Simplified coating cross-section — not to scale
The illustration is conceptual. Actual coating shrinkage and final film build depend on the coating system and application conditions.
Conversion Summary
Input
Wet film thickness—
Volume solids—
Solids fraction—
Result
Dry film thickness—
Micrometres—
Millimetres—
Mils—
Common Wet-to-Dry Examples
Wet Film
Volume Solids
Estimated Dry Film
Dry Film in Mils
100 µm
50%
50 µm
1.969 mil
100 µm
65%
65 µm
2.559 mil
150 µm
50%
75 µm
2.953 mil
150 µm
65%
97.5 µm
3.839 mil
200 µm
65%
130 µm
5.118 mil
250 µm
80%
200 µm
7.874 mil
300 µm
70%
210 µm
8.268 mil
Wet Film to Dry Film Formula
The theoretical relationship between wet film thickness and dry film thickness is based on the volume of non-volatile coating material remaining after curing.
DFT = WFT × (Volume Solids ÷ 100)
For example, if the wet film is 150 µm and the coating has 65% volume solids:
DFT = 150 × 0.65 = 97.5 µm
Reverse Calculation: Required Wet Film
When a target dry film thickness is known, the theoretical wet film thickness can be estimated by dividing the target DFT by the volume-solids fraction.
WFT = DFT ÷ (Volume Solids ÷ 100)
For example, achieving 100 µm DFT with 65% volume solids requires approximately 153.85 µm theoretical WFT.
Why WFT and DFT Differ
A wet coating contains volatile components that leave the film during drying or curing. The remaining solids form the dry coating film.
Higher volume solids generally means less thickness loss between wet and dry film.
Lower volume solids generally means a larger difference between WFT and DFT.
Actual film build can vary with application technique and substrate profile.
Some coating systems can behave differently from a simple idealized calculation.
Important Limitations
This calculator provides a theoretical wet-to-dry thickness estimate.
It does not measure actual wet film thickness.
It does not measure actual dry film thickness.
Use the coating manufacturer's stated volume-solids value.
Actual dry film thickness can be affected by substrate roughness and application conditions.
Multiple coating layers should be evaluated according to the coating system specification.
Solvent evaporation, curing and other coating characteristics can affect actual film build.
Final inspection should use a suitable calibrated coating thickness instrument.
Use this result for estimation and planning. For coating acceptance or specification compliance, follow the coating manufacturer's technical data, project specification and applicable inspection procedure.
Frequently Asked Questions
How do I convert wet film thickness to dry film thickness?
Multiply the wet film thickness by the coating's volume-solids percentage expressed as a decimal.
What is the formula for WFT to DFT?
DFT = WFT × (Volume Solids ÷ 100).
What happens when volume solids is 100%?
In the idealized calculation, the dry film thickness equals the wet film thickness because no volume is lost from the film.
Can I enter WFT in mils?
Yes. The calculator accepts micrometres, mils and millimetres.
Can the calculator show the result in mils and micrometres?
Yes. Every calculation displays the estimated DFT in all three common thickness units.
Does this replace a dry-film thickness measurement?
No. It is a theoretical estimate and should not replace actual coating inspection measurements.