Theoretical coverage for a floor coating is 1604 times the volume solids, divided by the dry film thickness in mils, in square feet per gallon. So a 100% solids epoxy at 10 mils covers about 160 square feet per gallon before losses. Measure the floor area from the plan, divide by that coverage for each coat, and add the allowance the manufacturer’s data sheet recommends. MeasureSet does the area and the arithmetic on your PC: measure each room on the PDF, give the coating label a unit of gallons and the area one gallon covers, and the totals show what to order.
Here is where the numbers come from and how to run them for a real floor.
Measure the floor on the PDF and get gallons per coat in the totals.
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Where does the 1604 number come from?
It is unit conversion, nothing more. NIST Handbook 44, Appendix C, defines the US gallon as exactly 231 cubic inches. A mil is one thousandth of an inch. Spread one gallon at a wet thickness of one mil and it covers:
- 231 cubic inches divided by 0.001 inch = 231,000 square inches
- 231,000 square inches divided by 144 = about 1,604 square feet
So one gallon of liquid, one mil thick, covers about 1,604 square feet. Theoretical coverage figures for coatings are derived from this conversion.
How do mils and volume solids change coverage?
Two numbers on the technical data sheet decide coverage:
- Volume solids is the share of the liquid that stays on the floor once the solvent or water has gone. A 100% solids epoxy leaves all of it; a 50% solids product leaves half.
- Dry film thickness (DFT) is how thick the cured coat should be, in mils. Data sheets often give the wet film thickness (WFT) too.
The formulas follow directly:
| You know | Coverage in sq ft per gallon |
|---|---|
| Wet film thickness | 1604 divided by WFT in mils |
| Dry film thickness and volume solids | 1604 times volume solids, divided by DFT in mils |
Calculated from the formula, before any losses:
| Product and thickness | Theoretical coverage |
|---|---|
| 100% solids at 8 mils DFT | about 200 sq ft per gallon |
| 100% solids at 10 mils DFT | about 160 sq ft per gallon |
| 100% solids at 20 mils DFT | about 80 sq ft per gallon |
| 50% solids at 4 mils DFT | about 200 sq ft per gallon |
| 75% solids at 3 mils DFT | about 400 sq ft per gallon |
The 50% solids line shows why volume solids matters: to leave 4 mils dry, you apply 8 mils wet, so a gallon covers half the area it would at 100% solids and 4 mils.
Why is real coverage lower than the formula?
The formula assumes a perfectly smooth, non-absorbent surface and no waste. Concrete is neither. Expect real coverage to fall short of theoretical because of:
- Surface profile. Ground or shot-blasted concrete has peaks and valleys that the coating fills before it builds thickness.
- Porosity. A primer coat on bare concrete soaks in, which is why primer coverage on data sheets is often stated separately.
- Application loss. Material left in the mixing bucket, on the roller and in the tray.
- Pot life. Mixed epoxy that cures before it is spread is lost.
Use the manufacturer’s practical coverage or loss allowance when the data sheet gives one, rather than inventing a percentage. If it gives only theoretical coverage, ask the supplier what allowance they recommend for your surface preparation.
How do you estimate epoxy gallons from a floor plan?
- Get the area right. Measure each room inside the walls, the area the coating actually goes on, and deduct anything that will not be coated, such as equipment pads or a pit.
- List the system coat by coat. A typical system might have a primer, a body coat and a topcoat. Each has its own thickness and its own coverage.
- Work out coverage per coat with the formula, or take the practical figure from the data sheet.
- Divide area by coverage for each coat to get gallons, then apply the allowance.
- Round up to the kit size the product is sold in, since two-part epoxies are packaged as matched kits.
A worked example
A 1,850 square foot floor, measured on the plan, with a hypothetical two-coat system:
| Coat | Product data | Coverage | Gallons before allowance |
|---|---|---|---|
| Primer | 50% solids, 4 mils DFT | about 200 sq ft per gallon | about 9.2 |
| Body coat | 100% solids, 10 mils DFT | about 160 sq ft per gallon | about 11.5 |
Then add the allowance from each product’s data sheet and round each coat up to whole kits. The numbers here are an illustration of the method, not a recommendation for any product; use the figures on your data sheet.
Give each coat its own label and coverage, and order per coat.
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What else should the estimate include?
- Cove base. If the coating turns up the wall as a cove, measure its length and height as a separate line.
- Broadcast media. Flake or quartz broadcast is usually ordered by area too, from its own coverage figure.
- Joints and cracks. Filler is measured by linear feet, so draw the joints as lengths.
- Different systems per room. A shop area and an office on the same plan may get different coats.
For the paint version of the same method, on walls, see our guide to estimating paint gallons from a floor plan PDF. For the area itself, see calculating flooring square footage from plans.
How does MeasureSet do the takeoff?
MeasureSet is PDF takeoff for flooring, paint, drywall and concrete bids, on your PC.
- Measure. Click inside a room to measure it wall to wall, even where walls are drawn as two lines. Draw lengths, areas, counts and segments, and deduct openings. MeasureSet reads the printed scale and offers it, and points snap to walls and lines. If you are not sure the scale is right, our guide to measuring PDF drawings to scale shows how to check it.
- Order. Give a label a unit and what one unit covers, and the totals show what to order, such as gallons. For epoxy, make one label per coat, set the unit to gallons, and enter the coverage you worked out.
- Rooms. Room names are read from the plan, and Excel gets a room schedule, which helps when rooms get different systems.
- Share. Export Excel with blank price columns, CSV, and a marked-up PDF with the totals. Compare a revision in red and blue when the plan changes.
There is no account and no upload, and your plan PDFs are never written over.
Frequently asked questions
Why do data sheets say 1604 and not 1600?
Because 231,000 square inches divided by 144 is 1,604.17. Rounding to 1600 changes the answer by about a quarter of one percent, which is small next to real-world losses.
Is the coverage on the can the same as the formula?
Not always. Some labels give practical coverage that already includes an allowance. Read which one the data sheet is quoting.
How do I convert mils to microns?
One mil is 25.4 microns, since an inch is exactly 25.4 millimetres.
Can MeasureSet calculate mils?
No. It measures areas, lengths and counts, and converts them with the coverage you give each label. The coverage comes from the formula and the data sheet.
Try MeasureSet
MeasureSet is a one-time purchase with a free trial in the Microsoft Store; the listing shows the current price and system requirements. Open your next floor plan, measure the coated area, and set up one label per coat. More detail is on the MeasureSet product page.
Turn a floor plan PDF into a coating order on your PC.
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Last updated 23 October 2026. Published by Automata Labs, a software company in Canada.