WFT/DFT Coating Coverage Calculator

Q: "What is the difference between WFT and DFT?"

"WFT is the film thickness right after application, while DFT is the film thickness left after drying. Volume solids are used to convert between them."

Q: "Are volume solids and weight solids the same?"

"No. Use volume solids for thickness conversion. If you only have weight solids, convert them separately first."

Q: "What loss rate should I enter?"

"Use a value that matches the application method, geometry, and your field experience. Higher overspray usually means a higher loss rate."

Q: "Can I use it without entering area?"

"Yes. Leave area blank if you only need the WFT and theoretical coverage calculation."

Q: "Can I mix metric and imperial units in one calculation?"

"No. Keep the entire calculation in one unit system at a time."

Back-calculate the wet film thickness and actual material usage from target dry film thickness, volume solids, loss rate, and area.

Switch between microns and mils while working through industrial coating stages, including heavy-duty coating jobs.

See DFT, WFT, theoretical coverage, and usage in one place

Supports microns / mils and m²/L / ft²/gal

Handles stripe coat and touch-up area shares

How to use

Choose the unit system.
Enter target DFT, volume solids, and coats for each stage.
Add area, loss rate, and area share if needed.
Review WFT, theoretical coverage, and actual usage.
Copy the result or share the current state if needed.

Samples

Two-stage heavy-duty coating (metric)

Input Area 100 m², loss rate 10%, Primer: DFT 75 µm, volume solids 80%, 1 coat, area share 100%, Topcoat: DFT 50 µm, volume solids 65%, 2 coats, area share 100%

Output Primer WFT 93.75 µm, theoretical coverage 10.67 m²/L, usage 10.42 L. Topcoat WFT 76.92 µm, theoretical coverage 13.00 m²/L, usage 17.09 L. Total 27.51 L.

Partial coating with stripe coat (imperial)

Input Area 10,000 ft², loss rate 10%, Stripe coat: DFT 3 mil, volume solids 80%, 1 coat, area share 25%

Output WFT 3.75 mil, theoretical coverage 427.78 ft²/gal, effective coverage 385.00 ft²/gal, actual usage 6.49 gal.

Formulas

WFT = DFT ÷ solidsFraction
Theoretical coverage = 1000 ÷ WFT(µm)
Theoretical coverage = 1604.1666667 ÷ WFT(mil)
Actual usage = Area × AreaShare × Coats × DFT ÷ (1000 × solidsFraction × (1 - lossRate))
Stage total DFT = DFT × Coats

Glossary

DFT

Dry film thickness left after curing. This is the main figure used in specifications and inspection criteria.

WFT

Wet film thickness immediately after application. Only the solids remain after drying.

Volume solids

The share of volume that remains as film. Use volume solids for thickness conversion.

Theoretical coverage

A no-loss coverage estimate derived from WFT.

Area share

The share of total area assigned to a stage, such as stripe coat or touch-up work.

Notes

This calculator uses volume solids, not weight solids.
Loss rate is a simplified model that varies with overspray, tool hold-up, container residue, and site conditions.
Area share can be set per stage. It works well for stripe coat and touch-up work.
Actual usage varies with the manufacturer's procedure, application method, temperature, humidity, and substrate condition.

FAQ

What is the difference between WFT and DFT?

WFT is the film thickness right after application, while DFT is the film thickness left after drying. Volume solids are used to convert between them.

Are volume solids and weight solids the same?

No. Use volume solids for thickness conversion. If you only have weight solids, convert them separately first.

What loss rate should I enter?

Use a value that matches the application method, geometry, and your field experience. Higher overspray usually means a higher loss rate.

Can I use it without entering area?

Yes. Leave area blank if you only need the WFT and theoretical coverage calculation.

Can I mix metric and imperial units in one calculation?

No. Keep the entire calculation in one unit system at a time.