Paint Coverage Calculator
Coating quantity for wood finishing from volume solids, dry film thickness and transfer efficiency - or straight from the data-sheet coverage.
Finishing shops buy paint by the litre and quote jobs by the square metre, and the bridge between the two is where money leaks. The technical route uses the coating's volume solids and target dry film thickness (theoretical coverage = 10 × solids% / DFT in µm), then discounts it by the transfer efficiency of your application method - conventional spray wastes around two thirds of the paint, HVLP most of that. Add an extra allowance for carved or moulded surfaces and price per litre, and you get litres and cost per job.
FAQ
How is paint coverage calculated from solids and DFT?
Theoretical coverage (m²/L) = 10 × volume solids % / dry film thickness in µm. A 40% solids coating at 35 µm covers 11.43 m²/L in theory - before any spray loss.
What is transfer efficiency and why does it matter so much?
It is the fraction of sprayed paint that actually stays on the part. At 65% (HVLP) the practical coverage is 7.4 m²/L and a 12 m² door needs 3.2 L for two coats; with a conventional gun at 35% the same job needs 6.0 L - almost double.
How much paint do I need for a door?
A flush door is roughly 3.5-4 m² per side; with edges call it 8 m². Two coats at a practical 7.4 m²/L takes about 2.2 L. Carved doors add 10-30%.
Should I use the data-sheet m²/L instead?
Use it when you apply by brush or roller and the substrate is cooperative - data-sheet figures assume no spray loss. For spraying, the technical mode with a realistic transfer efficiency predicts consumption far better.