This write-up defines polyurethane and shares few of its usual uses. It speak you exactly how to analyze manufacturer’s coverage estimates and how to plan for lot of coats that polyurethane. By the end, you’ll feel confident in estimating exactly how much polyurethane you need for your following wood finishing project.

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What Is Polyurethane?

Polyurethane, called ‘poly’ because that short, is a clear, tintable liquid applied to wood with a sprayer, brush, roller, or rag. It deserve to be oil or water based. It is a type of varnish the hardens with two phases.

In the 2nd phase, the film formed by polyurethane contracts together the molecule bind more closely together. This polymerization is dubbed ‘crosslinking’, and also happens together the complete is exposed come air. Because that water-based poly, this takes around 20 days. The takes as much as 30 days because that oil-based poly come cure.

How much Polyurethane do I Need?

Most polyurethane assets cover between 300 and also 600 square feet every gallon, and require in between two and also six coats to reach full protection.

The median American life room is 330 square feet. Planning for four coats, you need sufficient poly come cover 1,320 square feet, which would require two gallons and also one quart the polyurethane that covers 600 square feet per gallon, or 4 gallons and also one quart of polyurethane v a reduced coverage estimate.

Polyurethane Uses

Polyurethane is a popular choice for sealing and also protecting hardwood that is exposed come high level of usage or foot traffic. The repels moisture, staves off mold, mildew, and fungus. Of every the film-forming finishes, polyurethane is the most resistant to affect damage such together scuffing, denting, or scratches. 

For this reason, that is popularly used as a height coat for wood floors, occupational surfaces, and also tabletops. That can likewise be offered to complete interior furniture and trim.

Polyurethane can be used to safeguard exterior wood, but the inflexible barrier it forms on the surface of woods provides it less able come respond to transforms in temperature and also moisture content than penetrating oil finishes.

It has a high-gloss sheen, but satin and semi-gloss version are additionally available. It have the right to be mattified v scuffing v abrasive material. Polyurethane deserve to be tinted to act like a stain, or mixed with repaint for an ext opaque coverage.

How much Wood go a Gallon the Polyurethane Cover?

Polyurethane is a buildable end up that usually calls for multiple coats to achieve heavy-duty protection. Diluent coats will develop the finish more slowly, resulting in a an ext natural sheen, if thicker coats often tend to look at plasticy. 


The coverage the a gallon the polyurethane is dependent on the product. That is detailed on the container in square feet every gallon. This measure is only an estimate, and also there room several determinants that influence how accurate it is.

At the short end, some manufacturers calculation that a gallon of your product will cover 300 square feet. This kind of polyurethane is most likely to go on an extremely thick, which boosts the hazard of defects prefer hazing or bubbles. It is more challenging to apply than thinned polyurethane. Thinning polyurethane will rise the lot of timber you have the right to cover through a single coat, but an ext coats might be necessary to accomplish the exact same finish. 

At the other end of the range are manufacturers who insurance claim that one gallon can cover as lot as 600 or 700 square feet. Polyurethane with this label is usually thinner and easier come apply, yet again, much more coats may be necessary, for this reason it could not save you any money top top materials.

Plan on easy sanding the polyurethane in in between coats.

Read much more about how many coats the wipe-on poly you need.

How To calculate Polyurethane Coverage

Before you begin your following poly project, friend will should calculate exactly how much polyurethane you need. To make use of the manufacturer’s estimate, measure up in square feet every gallon, you require to understand how plenty of square feet you need to cover.

For objects with multiple surfaces, such together furniture, railings, and balusters, friend will must compute the surface area.

The formula because that area is size multiplied by width. For a square room with walls ten feet on each side, the area the the floor is 100 square feet.

To uncover the surface ar area that a three-dimensional object, discover the area of each confront and include them together, or usage a surface ar area calculator.

A table could have a top seven feet long and also three feet wide, for an area that 21 square feet. If the foot of the table space square shame posts, four inches to a side and also 36 inches tall, the area of every side is one square foot, for a total of 4 square feet every post, or 16 square feet if you add all four write-ups together.


If you to be going to use polyurethane to the whole table, you’d require to twin your calculation of the table top, to account because that polyurethane ~ above both sides.

As a preeminence of thumb, if a surface is less than a couple of inches wide or tall, such as the leaf of a fence, trim, or tabletop, that not usually worth calculating the area.

Instead, play it for sure by rounding up your calculation to the nearest quart. This accounts for minor spills, drips, or splashes.

Water-based polyurethane may take as plenty of as six coats to build up a robust layer of protection. 4 coats is generally the minimum. Oil-based polyurethane takes fewer coats; usually 2 or three.

In the example of the wooden floor, assuming 3 coats of oil-based polyurethane, the total area to be extended is 300 square feet. One gallon of polyurethane would most likely cover this area, nevertheless of brand.

In the wooden table example, let’s say 4 coats of water-based poly are required. 37 multiplied by 4 gives us 148 square feet. Depending on the brand of polyurethane friend choose, you might have the ability to get away v a single quart.


Polyurethane is a clear, tintable liquid the hardens right into a durable barrier that protects wood. The is most regularly used to protect interior furniture and also wooden floors. You deserve to estimate exactly how much polyurethane you require by calculating the area or surface area of the timber you desire to cover.

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Manufacturers calculation the amount of wood their assets cover, using square feet per gallon as the measure up of choice.

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