Work out what the slab takes before anyone quotes you for it.
Work out what your slab actually takes
This is a materials tool first. Give it the size of the slab and what the floor has to survive, and it works out the coating system, the film thickness that system needs, and the number of gallons and kits that thickness represents. It does not ask you how many gallons you want, because working that out is the entire job.
Buy this many kits
4
covering 3 separate layers at 33.0 mils total dry film
Last kit 23% of the final kit is actually used
The layers this floor is made of, and what each one costs in material
A resinous floor is not one thing rolled twice. It is a stack, and each layer in the stack has a different thickness, a different job, and therefore a different number of gallons. The wet column is what a wet-film gauge should read while you are working; the dry column is what you are left with.
| Layer | Dry film | Wet film | Coverage | Order |
|---|---|---|---|---|
| Penetrating primer | 4.0 mils | 4.0 mils | 401 sq ft/gal | 1.32 gal |
| Build coat | 17.0 mils | 17.0 mils | 94 sq ft/gal | 4.91 gal |
| Clear topcoat with slip aggregate | 12.0 mils | 12.0 mils | 134 sq ft/gal | 3.46 gal |
Sized for a domestic car or two, parked hot and turned on the spot, exposed to petrol, brake fluid, road salt and battery acid.
Where every gallon figure on this page comes from
A US gallon is 231 cubic inches by federal definition and a mil is a thousandth of an inch by federal specification. Spread one gallon out at one mil and it covers 231,000 square inches, which is 1,604.1667 square feet. That single number generates every quantity here.
- Take the film thickness the service condition demands. At the settings above that is 33.0 mils across 3 layers.
- Divide 1,604.1667 by that layer's thickness and multiply by the volume solids fraction, which gives the square feet one gallon of your product covers at that film.
- Divide the slab area by that coverage. That is the material the film physically contains.
- Gross it up for what is lost: 12% into an open profile on the priming coat, 5% into buckets and rollers on every coat.
- Round up to whole kits, because a two-part product cannot be reliably half-mixed by eye.
Working it the other way is a useful sanity check on any quote: multiply the square footage by the mils, divide by 1,604, and divide by the volume solids fraction. If a contractor's material allowance is well under that, either the film is thinner than they said or the coverage claim is optimistic.
Flags raised by this specification
Nothing flagged by the numbers you entered.
Reading the result honestly
- At one hundred percent volume solids the wet film and the dry film are the same number, which is the only case where a wet-film gauge reads the finished thickness directly.
- The last kit is barely broken into. A two-part product cannot be part-mixed reliably by eye, so plan what the remainder is for before you open it.
Two of the numbers above are our assumptions rather than facts about your product: the share of the first coat absorbed by an open profile, and the share lost to mixing and application. Both are disclosed on the methodology page, and both are replaceable by coating a measured ten-by-ten patch of your own prepared slab and seeing what you actually used.
Biggest swing factor Volume solids. A product at 45 percent solids needs more than twice the gallons of a 100 percent solids product for the same finished thickness, and the label rarely leads with it.