How much will 2 gallons of paint cover

Estimate how much paint in gallons or litres you would need to paint a room or external surface. This paint calculator supports doors and windows, number of coats and custom paint coverage efficiency. Internal painting calculation excludes the ceiling.

    Calculating how much paint you need

In order to calculate how much paint you need to paint a room, house, or an exterior surface, you need to either know the measurements by plan, or have a long measurement tape ready (10 or 20 meter / 33 or 65 foot long is advised) before you can use this paint calculator. If you are painting an interior surface, you need to know the room's width, length and height. Rooms with non-rectangular layout can be approximated to rectangles. If you need to paint a ceiling or external wall, switch to "External" in the calculator and just enter the total width and height of the wall (or width and length instead, for a ceiling).

Usually the room or exterior will have openings for windows and doors which need to be excluded from the total surface area. Accurate measurement of the windows is important, especially if there are many of them. Our tool only supports one set of window dimensions, so if you have a room with multiple windows of highly different dimensions, you'd need to use the average. In this how much paint do I need calculator door dimensions are assumed to be close to construction standards (200mm by 90mm).

The other important thing to consider is the paint coverage efficiency (a.k.a. spreading rate): how many square meters or square feet you can cover with a litre or gallon of the paint. Manufacturers usually provide this information on the product label. Different paints and primers have different coverage capacity so make sure you use the right number as input. You'd want to allow for a lower efficiency in case the surface is not smooth. More coarse surfaces require more paint to cover.

Finally, if you enter the paint price per gallon or per litre the output will include the total price of the paint required. The tool rounds up to the closest gallon or litre, but you might want to order more paint just to be on the safe side.

    Paint calculation example

One needs to paint two rooms top to bottom, excluding the ceiling. Both rooms have two windows each 3 feet wide by 4 feet high. Each room also has a door with standard dimensions (19.4 square feet or 1.8 square meters). The dimensions of the first room are 12 feet by 15 feet, and the second is 12 feet by 18 feet. Both are 8 feet high. What amount of paint is needed to cover all walls with two coats of paint?

First, calculate the total internal surface area of the rooms: (8 x 12) x 2 + (8 x 15) x 2 = 192 + 240 = 432 square feet for the first one; (8 x 12) x 2 + (8 x 18) x 2 = 192 + 288 = 480 square feet for the second room. In total: 912 square feet.

Second, calculate the total surface area of the windows: 4 x (3 x 4) = 48 sq ft. and then add the two doors: 48 + 2 x 19.4 = 86.8 sq ft.

Third, subtract the surface area of the windows and doors from the total initially calculated to get how the paint needs to cover: 912 - 86.8 = 825.2 square feet.

Finally, if the paint is known to cover 108 ft2 per gallon, and given that two coats are needed, divide the square footage by the paint coverage, then multiply by the number of coats to get: (825.2 / 108) x 2 = 7.64 x 2 = 15.2 gallons needed to paint these two rooms. Since usually you can purchase paint in whole gallons only, and also since one should always buy a bit more to be on the safe side, 16 gallons of paint need to be bought for this interior painting project.

Calculate how much paint and primer you need by entering the dimensions of your room below. Optionally, include ceiling paint in your estimate.

Room Dimensions

Width:

Length:

Height:

Include Ceiling

Paint Estimate:

Paint Area

Learn how we calculated this below

Add this calculator to your site

By

Joe Sexton

Joe is the creator of Inch Calculator and has over 20 years of experience in engineering and construction. He holds several degrees and certifications.

Full bio

Save on Pinterest Save Share on Facebook Share Share on Twitter Tweet

How to Calculate Paint and Primer

When you’re painting a room you might be wondering how many gallons of paint you’ll actually need. There are a few methods to figure this out.

The first method is to use the paint calculator above. It estimates the amount of paint, primer, and ceiling paint you’ll need for the project.

Simply enter the size of your room, and the calculator finds the square footage of the walls, then estimates the paint and primer needed for that area.

Of course, you can estimate paint without a calculator as well. You can calculate how many gallons you need in a few simple steps.

Get Free Project Estimates

Find Qualified Painting Professionals in Your Area

Enter your zip code to begin

How Many Gallons of Paint Do You Need?

The first step is to calculate how much paint you need. This is likely the most costly material and is often not returnable if you order too much, so getting it right is important.

By far, the easiest way to estimate how many gallons of paint you need for a project is to consult the quick reference table below.

Paint Coverage Estimates

This table shows the estimated amount of paint needed for average-sized rooms.

One gallon of typical latex paint usually covers 350 to 400 square feet of wall area.

How to Measure a Room

Using a reference table is quick and easy, but the most accurate method of calculating paint and primer for a project is to measure the surfaces to be painted and use the coverage estimate for the specific product you’re using.

Step One: Measure the Walls

The first step in estimating paint material is to measure the walls or ceilings you will be covering. Measure the length and height of each wall in feet and write them down. It may be easiest to round up to the next foot measurement for measurements that contain partial feet.

Step Two: Calculate Square Footage of Each Surface

The next step in the process is to calculate the square footage of the walls and ceilings. Square footage is an area measurement of a space, measured in feet, and we have a simple calculator to help with these calculations.

For each set of measurements from step one, multiply the width and height together to get the square footage. Make sure your measurements are in feet before multiplying. Write down the square footage of each wall.

For example, let’s find the square footage of a wall that is 10 ft. wide by 9 ft. high.

sq ft = 10 ft. × 9 ft.
sq ft = 90 sq ft

Pro Tip: use an area calculator to find the area of complicated wall shapes.

For walls that have large banks of doors or windows, consider subtracting the area of those from the wall square footage to avoid ordering too much paint. To do that, measure the length and height of each door and window and multiply to find the square footage. Then, subtract the door and window square footage from the wall square footage to find the area that needs paint.

If the walls are not simple rectangles or are complex, then consider breaking the wall into smaller sections and calculate the square footage of each section individually. To illustrate this, if your wall is not a normal rectangle, break it into different sections and measure the square footage of each section. Learn more about how to measure irregular walls.

Step Three: Add Square Footages Together to Find the Total

Once you know the square footage of each wall, add them together to find the total square footage. If you had split complex walls into several surfaces then be sure to add each surface to get the total.

For example, let’s find the total square footage for 2 walls that are 120 square feet and 2 walls that are 150 square feet.

total sq ft = 120 + 120 + 150 + 150
total sq ft = 540 sq ft

Step Four: Calculate Paint Coverage

The final step is to find the coverage ratio of your paint and calculate the number of gallons needed to cover the total square footage. Most professionals use the formula of 350 to 400 square feet of wall coverage per gallon of paint and 200 square feet of wall coverage per gallon of primer.

It’s important to note that different types and manufacturers may cover more or less area. It’s also important to note that different application methods such as spraying, rolling, or brushing will cover differently.

Your paint vendor should be able to tell you the coverage for your selected paint, and it’s often indicated on the container.

Divide the total square footage by the coverage rate to find the number of gallons needed.

For example, let’s find the paint needed to cover 540 square feet using a product that covers 350 square feet per gallon.

gallons = sq ft ÷ coverage
gallons = 540 ÷ 350
gallons = 1.54 gallons

How to Estimate Paint for Trim

Here’s a tip: estimate the paint and primer needed to cover trim or small surfaces by adding the size of the room and set the height of the room in inches to the height of the trim.

You can also estimate trim using the measurement method above. Start by measuring the height of the trim in inches, then convert that to feet. For example, trim that is 4 inches tall is .33 feet tall.

Then multiply the height by the length of trim to find the square footage. Then follow the rest of the steps above to estimate the paint needed to cover that square footage.

How to Estimate Exterior Paint

You can estimate exterior paint you’ll need just like interior projects. Start by measuring each exterior wall of the home, then calculate the square footage of each one.

For walls with a gable, measure the square portion and the gable portion separately. You might find a triangle area calculator helpful to find the square footage of the gable.

The, add the square footage of each area together. Subtract the square footage of any doors and windows that you won’t be painting from the total square footage.

Consult the directions on the specific product you’ll be using for a coverage estimate.

Keep in mind that walls with porous surfaces such as concrete, brick, or rough wood will soak up much more paint than a smooth surface. We suggest ordering more paint than you estimate to cover these surfaces.

When making dramatic color changes you might also need an additional coat of paint to get adequate coverage; be sure to account for this in your estimate.

Estimation Tips

It may be a good idea to order 10-20% extra, probably an extra quart or gallon depending on your project, to allow for differences in coverage and to have extra material for touch-ups down the road. If you are fairly close to an even gallon on a small project and want to save some money, consider ordering a quart for your overage.

Don’t forget to estimate other supplies needed for a painting project. Learn more about the costs associated with a painting project.

Be sure to grab plenty of tarps and use a good blue masking tape to tape off any surfaces for a clean paint job. Finally, make sure you choose a good brush and rollers; spending an extra dollar or two on these will have just as much impact on your finish as the quality of the paint itself.

How much paint is needed for a 12x12 room?

How many gallons of paint do I need for a 20x20 room?

How much paint do I need for 2 coats?

How many square feet does 3 gallons paint cover?