How Many Gallons of Paint Needed to Paint a House

Gallons of Paint Needed to Paint a House

Wondering how many gallons of paint needed to paint your home is normally one of the first questions every painter calculates before going to the paint store. Having this knowledge before heading to the paint store makes you much more mindful and informed, than walking into your local Sherwin-Williams paint store saying "I'm painting my house, how many gallons of paint do I need".

You'll be an expert knowing how many gallons of paint you need, after reading this article, before walking non-nonchalantly into a paint store! How_Many_Gallons_Does_It_Take

Since there are so many variables to this calculation, that particular question can be somewhat humorous to even the most seasoned painter or paint store clerk, and we will address the most common ones below.

Other funny sayings could include, ''Just make that paint color just a little bit darker'', but we will address that in another article all together.

Understanding these variables can help you save hundreds of dollars in the long run, knowing you cannot return tinted colored paint, even if it's unopened, unless of course that product is a stocked product right off the shelf.

Also, who wants to store excessive gallons or 5 gallon buckets in your garage or basement when your painting project is completed, and you've washed your hands of this labor intensive honey-do project, having another one on your list to complete? I know I don't.

Knowing What Areas of Your Home to be Painted?

Determining which areas to paint your home will outline your scope of work, and areas to calculate paint needed. Generally homeowners first thought is painting the bare minimum, as cost is a factor. However, most homeowners who are doing it themselves or hires a qualified painting contractor quickly finds that just painting the trim looks so good, might as well do the walls also, and visa-versa.

This follows the same with painting your exterior surfaces as well. When only doing one portion of an entire surface, and not doing the rest, blemishes will certainly stand out, convincing yourself to paint the entire section. Not to mention painting one section and not the other is harder having nice crisp straight lines.

Other reasons for painting entire sections is not only does painting complete areas allows for a uniform and precise finish, but you don't have to worry about painting the other section sooner than later.

When your trim is showing peeling, cracking, bubbling, or blistering, you can bet the paint on the siding is just as old, probably showing fade. And paint fade is the first thing to go on paint deterioration, so unless your flipping houses, doing things a bare minimum, you'd better paint or have it all painted. That old adage cliche' has never been more prominent, ''Do it right the first time, then you never have to go back''.

Another reason to consider areas to be painted involves one of the most important facets of painting, which is caulking. If painting only the trim, and the siding color is different than the trim, it is almost impossible to apply new caulk where siding meets the trim, unless you paint the entire section trim and siding.

Well, you say ''Let's just touch-up the siding where new caulk is applied''. That's a good initial thought to cut corners, saving the bulk of exterior paint, but matching paint fade is ultimately impossible, and better off not painting at all, since no one likes a poky-dotted house, unless your a clown for Barnum -n- Bailey.

What's worse than seeing fresh new paint patches in the middle of dried, faded paint. Therefore in Denver, CO. most homes are painted completely, as painting contractors are avid paint professors to the general public in this regard, instructing and advising to paint entire exterior when it becomes a necessity.  For interior painting, caulking is vitally important whether your painting only walls or just the trim, as it helps having the sharpest crisp lines after the tape is pulled.

So, if your considering painting a Master bedroom or Living room, better have a few tubes of White Latex Caulk and Caulking gun available before you get started. A good caulk to use is Sherwin-Williams 950 which is a 55yr. caulk, which goes on very smooth, having the highest degree of sealant protection either for interior or exterior applications.

Variables to Consider When Estimating Paint Quantities

Important variables to consider when you are assessing your next painting project is important so you don't have an excessive amount of paint left over after the job is all done. Trying to figure out how many gallons of paint needed to paint your house can be a daunting task, with so many variances. These variances should include;

  1. Same color, or Color change.
  2. Are you painting light over dark, or dark over light colors
  3. How porous or non-porous is your substrate
  4. How many square feet does your paint normally cover
  5. How many coats of paint do you intend applying
  6. What is the actual square footage of your painting surface

Painting the same color, or changing the color is important in that your gallon of paint will cover much more than what the suggested coverage recommends printed on the can. This is important for interior paints, however exterior coatings require two coats, wet on dry application for product warranties to be fully enforced, unless Life-Time paints, which is a one coat application.

Painting over the same color, can save you approximately 5-10% of paint still left in the can. Changing the color, you had better stick with what the product label states, anywhere from 200-250 sq. ft. of surface area.

Are you painting light colors over dark deep base ones? Or are you painting deep base colors over light colored walls. Either way, unless you use a tinted primer of similar finish coat color, you'd better plan on doubling your paint gallon estimate, as paints only cover half of the recommended stated coverage.

Less expensive to use a P.V.A Poly (vinyl acetate) primer first, which usually comes in a Flat paint finish, allowing your finish coat to go on much more evenly.

The porosity of your substrate is important to consider, knowing how much your paint will soak into the surface, leaving a mil thickness on top, which you and others enjoy. If your surface is very porous, you will need more than recommendations stated on the can, and visa-versa for solid non-porous surfaces, allowing all product to lay on top.

Most paint manufactures estimate paints covering from 200 square foot (sq. ft.) to 250 sq. ft. of painted surface. You will have to check, reading the back of each label. Reasons for variances is the viscosity of the paint itself. Typically, the thicker the viscosity, the less sq. ft. the paint is going to cover, or you'll be working much harder spreading the same amount over a larger area, reaching the same results.

This leads nicely to how many coats of paint do I intend on applying. In some instances you can get by with one, but more than not, you'd better plan on two or sometimes three.

Figuring the actual square footage of the painted surface is last but not least. Know putting this off until the last is just what you had in mind too. And No, I cannot read your mind, but arithmetic is always saved for last, being the best, and absolute.

Calculating Gallons of Paint Needed Calculating_Gallons_of_Paint_Needed

Not wanting to get too technical and bogged down with mathematical formulas, I have developed a way of figuring the number of gallons almost down to a science, not taking an afternoon behind a calculator.

Just so you know, Math was one of my worst subjects in High School, but applying something to make my life much easier. I know the numbers below look a lot, but once you master it, there is only a few you will use in real life, just like Algebra was in High School.

Interior Paint Gallon Calculations

If a 10' X 10' room with an 8' ceiling is to be painted = 10' wide X 8' tall X 4 = 320 sq. ft.
If the ceiling is to be painted add 100 sq. ft. more = 420 sq. ft.

If a 10' X 10' room with 9' ceiling is to be painted = 10' wide X 9' tall X 4 = 360 sq. ft.
If the ceiling is to be painted, add 100 sq. ft. more = 460 sq. ft.

If a 10' X 10' room with a 10' ceiling is to be painted = 10' wide x 10' tall X 4 = 400 sq. ft.
If the ceiling is to be painted, add 100 sq. ft. more = 500 sq. ft.

If a 10' X 10' room with a 12' ceiling is to be painted = 10' wide X 12' tall X 4 = 480 sq. ft.
If the ceiling is to be painted, add 100 sq. ft. more = 580 sq. ft.

Now you can see where I'm going with this, making it very easy to calculate an entire interior home, as you move the decimal over one, using these figures!

8' > 3.2 4.2
9' > 3.6 4.6
10' > 4.0 5.0
12' > 4.8 5.8
14' > 5.6 6.6
16' > 6.4 7.4
18' > 7.5 8.5
20' > 8.0 9.0

Times the total sq. ft. of your home, adding ceilings, which is 1 more whole number! Then dividing average gallon coverage, this being 250 sq. ft.

  • 8' Ceiling Height 
    2000 sq. ft. X 3.20 or 3.2 = 6400 sq. ft. (250) = 26 gallons
    Adding ceiling is 2000 sq. ft. X 4.2 = 8400 (250) = 34 gallons

3000 sq. ft. X 3.2o or 3.2  = 9600 sq. ft. (250) = 38 gallons
Adding ceiling is 3000 sq. ft. X 4.2 = 12,600 (2) = 50 gallons

  • 9' Ceiling Height
    2000 sq. ft. X 3.60 or 3.6 = 7200 sq. ft. (250) = 29 gallons
    Adding ceiling is 2000 sq. ft. X 4.6 = 9200 (250) = 37 gallons

3000 sq. ft. X 3.6o or 3.6 = 9600 sq. ft. (250) = 38 gallons
Adding ceiling is 3000 sq. ft. X 4.6 = 12,600 (250) = 50 gallons

  • 10' Ceiling Height
    2000 sq. ft. X 4.00 or 4.0 = 8000 sq. ft. (250) = 32 gallons
    Adding ceiling is 2000 sq. ft. X 5.0 = 10,000 (250) = 40 gallons

3000 sq. ft. X 4.00 or 4.0 = 12,000 sq. ft. (250) = 48 gallons
Adding ceiling is 3000 sq. ft. X 5.0 = 15,000 (250) = 60 gallons

  • 12' Ceiling Height
    2000 sq. ft. X 4.80 or 4.8 = 9600 sq. ft. (250) = 29 gallons
    Adding ceiling is 2000 sq. ft. X 5.8 = 11,600 (250) = 46 gallons

3000 sq. ft. X 4.80 or 4.8 = 14,400 sq. ft. (250) = 58 gallons
Adding ceiling is 3000 sq. ft. X 5.8 = 17,400 (250) = 70 gallons

  • 14' Ceiling Height
    5.6 for walls only
    6.6 for walls and ceiling
  • 16' Ceiling Height
    6.4 for walls only
    7.4 for walls and ceiling
  • 18' Ceiling Height
    7.5 for walls only
    8.5 for walls and ceiling
  • 20' Ceiling Height
    8.0 for walls only
    9.0 for walls and ceiling


Giving you some homework, will let you plug in these factors, the last four ceiling heights, knowing you will be spot on your estimations as well.

This is just 1 cost factor painting interiors, knowing there are many more to consider. If planning to paint in the near future, you may want to consider the other important areas that directly effect the final out-of-pocket expense you will incur.

Those can be found at; https://paintingdenver.net/interior-painting/denver-interior-painting-costs/
as Denver is an average across the nation, giving you a good barometer what you might expect, rolling up your sleeves, and either getting your paint clothes on, or hiring a qualified painting company to handle this for you.

Exterior Paint Gallon Estimations

Same principals estimating paint apply for exterior siding and trim. Multiplying the height times the length, then dividing the average coverage per gallon. Exterior paints cover the same sq. ft. as interior ones, however, you must remember to include soffit, gutters, and any extensions such as chimneys, sheds, and awnings, porches, roof covers, & overhangs. Generally speaking, the number of gallons for trim is 1/5th the number of main color for siding. If your home has much more trim than normal, like a Nordic Look, or your soffit is the trim color, the number of trim color gallons will increase to say 1/4th of siding gallons for proper 2 coat coverage.

A Quick Review of Exterior Paint Gallon Coverage

Ultimately depends on the size of your home, how many gallons outside will be needed to properly paint your home. However, there are some variables in this regard as well.

  • What is the sq. ft. of your home's living space
  • What type of exterior do you have
  • How good is your painted surfaces right now
  • Number of paint coats you plan to apply

Understanding how large your home is, has a direct impact on the size of your exterior surfaces protecting you inside. Knowing this, we are going to assume most of your exterior is painted, unless you have a brick home, not wishing to paint that.

Most of the homes in Colorado, North West, New England, and South West have less brick, and more painted surfaces such as Masonite™,  Stucco, or Cedar siding, which we will use calculating.

Visually looking at your exterior siding first will give you a good idea what condition your paint is currently in. Remembering paint fade is the first thing to go for exterior paint. After this takes place, the coating breaks down, allowing water to penetrate the surfaces through nails and fasteners, causing the outer layer to swell, and deteriorate. So pay close attention to the bottom edges of your siding. If some have swelled out being thicker, you can bet it's time to paint that siding also.

Depending on the severity of your exterior, where there is a lot of peeling, cracking, blistering of paint, it is advised to scrape first problem areas, and then either prime with with a high bonding primer, or use a primer built into the paint mixture, requiring a one coat application. These paints that have primers built into the paint formulations are generally much more expensive, some considered Life-Time paints, resisting paint deterioration over a longer period.

Stucco surfaces require an Elastomeric paint, developed specifically for Stucco, weather proofing, filling in bridging in tiny cracks that normally develop over years of settling. This is extremely important using this for Stucco, as when dried, has a Flat paint sheen finish, looking like part of the Stucco itself. Conflex™ by Sherwin-Williams is by far the very best Elastomeric paint available on the market today. Three important criteria in determining the best Elastomeric paint is Elasticity, Elongation, and Tensile Strength, all three winning the competition hands down! Proper application requires a three coat application, Brush, Back Roll, and Spray again.

If not using a Life-Time paint, such as Harmony™ or Duration™ by Sherwin-Williams™, a two coat wet on dry application is recommended for a 25yr product warranty. Your either going to spend more money initially for the paint, or spend more time painting with a lesser quality paint itself, so it's up to you. Unless of course you do not want to do either one, and hire a professional to handle this matter for you. Eco Paint, Inc. painters in Denver, who follows paint manufactures recommendations to a tee, painting 1000's of homes across Colorado's Front Range each year with exceptional quality, and professional results.

So an Average Home's Size and Gallons of Paint Needed Painting Exteriors

These estimates below are average across most exterior painting, but your quantities may vary, depending on surfaces, and applications.

Siding Paint Needed, 2 Coats -- Trim Paint Needed, 2 Coats

Siding Paint Needed, 2 Coats Under Roof Home
Siding Paint Gallons Trim Paint Gallons
1050 Sq. Ft 30' X 35' 10 Gallons 2 Gallons
1800 Sq. Ft 40' X 45' 12 Gallons 3 Gallons
2000 Sq. Ft 40' X 50' 13 Gallons 3 Gallons
2250 Sq. Ft 45' X 50' 14 Gallons 3 Gallons
2500 Sq. Ft 50' X 50' 15 Gallons 4 Gallons
2750 Sq. Ft 50' X 55' 16 Gallons 4 Gallons
3000 Sq. Ft 50' X 60' 17 Gallons 5 Gallons
3250 Sq. Ft 50' X 65' 18 Gallons 5 Gallons
3500 Sq. F 50' X 70' 19 Gallons 6 Gallons
3750 Sq. Ft 50' X 75' 20 Gallons 6 Gallons
4000 Sq. Ft 50' X 80' 21 Gallons 7 Gallons
4250 Sq. Ft 60' X 70' 22 Gallons 7 Gallons
4500 Sq. Ft 60' X 75' 23 Gallons 8 Gallons

Knowing these longer warranty paints cost much more, it's even more important to estimate your gallon quantities, knowing that you can't return unopened cans for refund. Let's say you have 2 - 5gallon buckets of paint left over, costing $245.00 each, you just ate $490.00. I don't know about you, but I could use an extra $490.00. Take the family out for dinner and a movie or Baskin-Robbins afterwards, I don't know.

Hoping this helps you figuring your next purchase of paint painting your interior or exterior, remembering you'll want at least a portion left over, say 1/2 of a gallon for any touch-ups later, after you've had a chance to look over more carefully. Would like to hear from you on your thoughts & experiences below!

Additional information can be found at Your best & free Denver house painting prices! Concise paint costs, quotes, estimates from Denver, Boulder, Aurora, to Colorado Springs, CO. Eco Paint, Inc.

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  1. […] when brushed and rolled. I will not bore you with mathematical calculations how to figure the amount of paint to buy, painting you're entire home, speaking here how much paint to buy for a particular […]

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