Type a line (VS 60 % DFT 125 um 1200 m2; 20 l cans VS 60 % 125 um 1500 m2; 200 l on 1000 m2 VS 60 %) or fill in the fields: the line and the fields stay in step.
Enter the volume solids from the product data sheet, the dry film thickness from the coating specification and the area, and the calculator gives the theoretical spreading rate in m2/l, the wet film thickness and the litres for the area; with a loss entered, the practical quantity, then the number of coats and the cans of a size you enter. In reverse, it gives the dry film a volume of paint gives on an area. The working is shown with your numbers, a drawing sets the wet film against the dry film to the same scale, and the result is a line you can copy or add to a request.
Arithmetic only: the calculator does not choose a paint or a coating system and suggests no film thickness, loss figure or price. The theoretical figure is for a smooth surface with no losses; the practical figure depends on the application method, the surface profile and the conditions, and the data sheet of the paint maker governs.
Theoretical spreading rate = VS x 10 / DFT: at 60 % volume solids and 125 micron dry this is 60 x 10 / 125 = 4.8 m2/l, so 1200 m2 needs 1200 / 4.8 = 250 l. Wet film = DFT x 100 / VS = 208.3 micron; with 10 % thinner, 125 x 110 / 60 = 229.2 micron. The figures are an example; take yours from the data sheet.
Practical quantity = theoretical / (1 - loss / 100): 250 l with a loss of 30 % (an example) is 357.1 l. The litres per coat are multiplied by the number of coats, and the total is divided by the can size and rounded up: 312.5 l in 20 l cans is 16 cans, the last one part-used.
DFT = VS x 10 x litres / area: 200 l of a paint with 60 % volume solids on 1000 m2 gives 60 x 10 x 200 / 1000 = 120 micron dry in one coat, in theory. With a loss the litres are reduced first; with several coats they are shared between them.
| Volume solids | 50 micron | 75 micron | 100 micron | 125 micron | 150 micron | 200 micron |
|---|---|---|---|---|---|---|
| 40 % | 8.00 | 5.33 | 4.00 | 3.20 | 2.67 | 2.00 |
| 50 % | 10.00 | 6.67 | 5.00 | 4.00 | 3.33 | 2.50 |
| 60 % | 12.00 | 8.00 | 6.00 | 4.80 | 4.00 | 3.00 |
| 70 % | 14.00 | 9.33 | 7.00 | 5.60 | 4.67 | 3.50 |
| 80 % | 16.00 | 10.67 | 8.00 | 6.40 | 5.33 | 4.00 |
| 100 % | 20.00 | 13.33 | 10.00 | 8.00 | 6.67 | 5.00 |
This is arithmetic from the formula, not the data of a paint and not a recommended thickness: the volume solids of your paint is on its data sheet, and the film thickness is in the coating specification. The practical rate in m2/l is the theoretical one times (1 - loss / 100).
The working is plain arithmetic. The theoretical spreading rate VS x 10 / DFT and the wet film thickness DFT x 100 / VS are given in the technical notes of two protective coating makers. The wet film with thinner, DFT x (100 + thinner %) / VS, is given by one of those notes and by the reference chart of a coating gauge maker. The quantity with losses, the theoretical quantity divided by (1 - loss / 100), is given by both notes: one as the volume of paint with wastage, the other as the theoretical rate times a coverage efficiency. The typical losses those sources state differ, so the calculator gives none. 1 ft2 = 0.09290304 m2, 1 US gal = 3.785411784 l and 1 mil = 25.4 micron are exact by definition (1 in = 25.4 mm). The data sheet of the paint maker always comes first.
The theoretical spreading rate is the volume solids times 10 divided by the dry film thickness: a paint with 60 % volume solids applied at 125 micron dry covers 60 x 10 / 125 = 4.8 m2 per litre. The litres for an area are the area divided by that rate: 1200 m2 / 4.8 m2/l = 250 l for one coat. These are example figures: the volume solids comes from the product data sheet and the dry film thickness from the coating specification. The result assumes a smooth surface and no losses.
The wet film is the dry film times 100 divided by the volume solids: for 125 micron dry at 60 %, 125 x 100 / 60 = 208.3 micron wet. Thinner adds liquid but no solids, so with thinner the wet film is DFT x (100 + thinner %) / VS: with 10 % thinner, 125 x 110 / 60 = 229.2 micron wet for the same dry film. The litres of paint and the spreading rate in m2/l do not change: both are for the paint before thinning, and the thinner comes on top. Whether a product takes thinner, and how much, is on its data sheet.
Enter a loss in per cent, and the practical quantity is the theoretical one divided by (1 - loss / 100): 250 l with a loss of 30 % is 250 / 0.7 = 357.1 l. The 30 % is an example only. The loss depends on the application method, the surface profile after preparation, the shape of the work and the conditions on the day, so the calculator suggests no figure: it comes from experience on similar work or from the paint maker. An efficiency entered instead (efficiency 70 %) is read as a loss of 30 %.
The litres for all coats, with the losses when a loss is entered, are divided by the can size and rounded up: 312.5 l in 20 l cans is 15.6, so 16 cans holding 320 l: the last can is part-used, with 7.5 l left over. For a product supplied as two components, enter the volume of one mixed kit as the data sheet gives it.
Turn the formula round: DFT = VS x 10 x litres / area. 200 l of a paint with 60 % volume solids on 1000 m2 gives 60 x 10 x 200 / 1000 = 120 micron dry, in theory and in one coat. With a loss entered, the litres are reduced by the loss first; with several coats, they are shared between the coats.
The area in m2 or ft2 (1 ft2 = 0.09290304 m2 exactly); the film thickness in micron, mil (1 mil = 0.001 in = 25.4 micron exactly) or mm; the volume and the can size in litres or US gallons (1 US gal = 3.785411784 l exactly). Imperial gallons are not taken. The volume solids, the loss and the thinner are in per cent.
The calculator works out quantities only. When paint is needed, send the product name from the specification, the colour, the litres and the can sizes, with the data sheet or a photograph of the old can label, and Vessel Core checks the details before an offer goes back.
