Polyurea Calculator

1. Pick Imperial or Metric. Enter the area to coat and the dry film thickness in mils or microns.
2. Enter the volume solids from the product data sheet and a loss allowance for overspray and surface profile.
3. Enter the kit size and your price per gallon or liter. Read the gallons to buy, the coverage rate, the wet film thickness, the kits and the cost.

A polyurea calculator is a coating quantity tool. It turns an area and a film thickness into the volume of liquid coating to buy. Polyurea is a fast-curing, two-component elastomer coating used on floors, tanks, truck beds, roofs and road markings.

It helps applicators pricing a job, facility managers checking a quote, and homeowners comparing a garage floor coating with other options. The same math works for any liquid coating whose data sheet lists volume solids, including epoxies and urethanes.

It does not choose a thickness for you. Thickness comes from the project specification or the product data sheet. For resin you pour and cast, use the resin and epoxy calculator; for wall paint, use the paint coverage calculator.

The calculator spreads one gallon into a film of the chosen dry thickness and asks how much area that film covers.

Where 1,604 Comes From

1. A gallon is 231 cubic inches. NIST Handbook 44 defines the US gallon as exactly 231 cubic inches.
2. A mil is 0.001 inch. NIST SP 811 lists the mil as 0.001 in, or 25.4 micrometers.
3. Spread it thin. 231 cubic inches at 0.001 inch thick covers 231 / 0.001 = 231,000 square inches.
4. Convert to square feet. 231,000 / 144 = 1,604.17 square feet per gallon at 1 mil, for a coating that is 100 percent solids.

Volume solids is the share of the liquid that stays in the cured film. At 80 percent solids, only 0.8 gallon of each gallon remains, so coverage drops to 1,283 square feet at 1 mil. In metric, 1 liter at 1 micron covers exactly 1,000 square meters, so coverage is 1,000 x solids / microns.

Floor coating. A 500 sq ft floor at 30 mils and 100 percent solids: coverage is 1,604.17 / 30 = 53.47 sq ft per gallon. The net volume is 500 / 53.47 = 9.35 gallons. With a 10 percent loss allowance, buy 10.29 gallons, which is 3 kits of 5 gallons. At $100 a gallon, 15 gallons cost $1,500.00.

Road marking. North Carolina DOT asks for at least 20 mils dry on concrete and asphalt. A 4 inch line 1,000 feet long covers 333.33 sq ft. At 80.21 sq ft per gallon, that is 4.16 gallons before loss.

Lower solids product. A 1,000 sq ft area at 20 mils with a 95 percent solids product covers 76.20 sq ft per gallon. It needs 13.12 gallons net, sprayed at 21.1 mils wet to leave 20 mils dry.

Metric tank lining. A 500 sq m tank at 500 microns and 100 percent solids: 1 liter covers 2 sq m, so the net volume is 250 L. A 15 percent loss makes it 287.5 L.

Real coverage is always lower than the theoretical figure, and the gap depends on the surface and the application.

Volume Solids

Coverage rises and falls in step with solids. A product at 70 percent solids covers 30 percent less area per gallon than a 100 percent solids product at the same dry thickness.

Surface Profile and Porosity

Blasted steel, shot-blasted concrete and textured surfaces hold coating in their valleys before the film builds. NCDOT raises its marking minimum from 20 to 30 mils on textured surfaces such as open-graded friction course.

Overspray and Equipment Loss

Spray fans miss edges, wind carries mist, and plural-component hoses and mixers hold material. Enter these in the loss allowance, which is your own estimate.

Film Build Uniformity

Applicators spray above the minimum so the thinnest spot still passes. Planning at the minimum means some areas will fall short.

Wet Versus Dry Thickness

For products under 100 percent solids, the wet film shrinks as solvent leaves. Wet mils = dry mils / volume solids.

Material cost is whole kits times kit size times your price, and material is only part of a coating budget.

Compare the cost per square foot with other floor finishes before you decide. For a tiled floor instead, the tile calculator gives a box count and cost.

Floors and Garages

Measure the floor, add any coved base, and use the thickness from the system data sheet. Add primer and topcoat as separate runs.

Road and Parking Markings

Convert line length to area: length x line width in feet. Illinois DOT specifies polyurea marking as a 100 percent solids two-part system, so solids stay at 100.

Tanks, Liners and Roofs

Use the full internal surface area, and a larger loss allowance for complex shapes. The paint quantity guide covers measuring walls and ceilings.

1. Using 1,600 Instead of 1,604

Rounding the constant to 1,600 understates coverage by 0.26 percent. Small, but it adds up on large jobs.

2. Confusing Mils and Millimeters

A mil is 0.001 inch, or 0.0254 mm. 30 mils is 0.76 mm, not 30 mm.

3. Ignoring Volume Solids

Using 1,604 for a 60 percent solids product overstates coverage by two-thirds, and the job runs short.

4. Planning with Zero Loss

The theoretical figure assumes every drop lands in an even film on a flat surface. That never happens on site.

5. Mixing Up Weight Solids and Volume Solids

Coverage depends on volume solids. Data sheets often list both, and they are rarely the same number.

The theoretical coverage is exact from the definitions of the gallon and the mil. The real quantity depends on your loss allowance.

At 100 percent solids, one gallon covers 1,604 square feet divided by the dry mils. That is 80.2 square feet at 20 mils and 53.5 square feet at 30 mils, before any loss.

A US gallon is exactly 231 cubic inches. Spread at 0.001 inch, it covers 231,000 square inches, and 231,000 / 144 = 1,604.17 square feet.

Multiply 1,604 by the solids fraction. A 75 percent solids product covers 1,203 square feet per gallon at 1 mil, so it needs a third more material than a 100 percent solids product.

One mil is 25.4 microns, or 0.0254 mm. So 40 mils is 1,016 microns, or about 1.02 mm.

There is no single standard figure. It depends on the surface, wind, equipment and applicator, so ask your applicator or use a figure from past jobs.

Measure the floor. A 24 by 24 foot garage is 576 square feet. At 30 mils and 100 percent solids, that is 10.77 gallons before loss.

Yes. The math is the same for any liquid coating. Enter the volume solids and dry thickness from that product data sheet.

Wet film is what you spray, and dry film is what remains after solvents leave. For 100 percent solids they match; otherwise wet mils = dry mils / solids.

No. Coating prices vary widely by product, region and order size, so the calculator only uses the price you enter.

No. The calculation runs in your browser and nothing is sent to our servers. Anything you choose to Save stays in this browser only.

• NIST Handbook 44, Appendix C: 1 US gallon = 231 cubic inches exactly (National Institute of Standards and Technology).
• NIST SP 811, Appendix B.8: the mil (0.001 in) and gallon conversion factors (NIST).
• Polyurea pavement marking media and thickness: 20 and 30 mil minimum dry thickness (North Carolina Department of Transportation).
• Special provision for polyurea pavement marking: 100 percent solids two-part system (Illinois Department of Transportation, Word document).