How Much Paint Do You Need for Interior & Exterior House Painting?

how much paint do i need to paint my house

Estimating the amount of paint you will need to paint your house is not an exact science.

Too little and you wind up buying more than expected. Too much and you have wasted your money with useless paint that is leftover.

When you consider that the average liter of good quality paint can run $35, which becomes less per liter with the more paint you purchase, understanding how much you need will make a considerable difference in staying within your budget.

Generally speaking, it is better to have a little too much paint compared to too little because of the lower price per liter.

Plus, you may be able to use the excess paint for other areas, such as a feature wall or painting items around the home.

As a general rule you will be using about 1 gallon of paint for every 350 square feet of surface footage of the surface area you want to paint.

Having said that, you do not want the excess amount to be too much. Otherwise, you will have cans of paint sitting around your home doing nothing.

Well, if you are planning to paint your house and wondering how much paint will you need, let’s start with some estimates and calculations.

Remember, it will generally depend on the coverage of paint you need for interiors and exteriors of your house.


How Much Paint Do I need for Interiors?


how much paint

This is a difficult question because interiors may require you to paint items apart from the walls.

You will need to add up the items you want to cover and then calculate how much paint will be needed.

You can start with the manufacturer’s recommendations which are usually found on their website and sometimes on the side of the cans.

However, the actual coverage rate can vary depending on the brand and the surface that needs to be covered.

For example, if you are covering a wall that has already been painted and you do not want to remove the underlying paint, then the manufacturer’s coverage rate should be about right.

However, if you are covering an unpainted area, then you may need about two times the amount of paint. The difference is because you will need additional coats of paint to fully cover the area properly.

A general guess for interiors starts by assuming a standard room that is 12’ x 12’ x 9’. From there, the following calculations can be made;

Interior AreaPaint Quantity
Ceiling½ Gallon
One Wall1 Gallon
Sealer or Primer1 Gallon
Feature Wall¼ to ½ Gallon
Woodworking or Trim¼ Gallon

Naturally, the larger the room, the more paint will be needed. You should start by adding up all rooms that need to be painted.

For larger rooms, add whatever paint is needed while smaller rooms will need less. This should give you a rough amount.


How Much Paint Do I Need for Exteriors?


Generally speaking, exterior walls are usually easier to calculate the amount of paint needed compared to interiors.

The surface areas of exteriors are generally flat and have fewer corners or unique angles as compared to interior surfaces.

However, the exterior areas are subject to far more stress due to the ultraviolet rays of the sun along with erosive elements such as wind, rain, hail, and snow.

This can be compensated by the toughness and durability of the paint that is used for exterior surfaces.

In this case, the same rule as for interior surfaces applies.

Namely, that if you are covering surfaces that have already been painted and you do not remove the underlying paint, then the coverage area as indicated by the manufacturer should be close.

If you are removing the underlying paint or the area has yet to be painted, then you will probably need twice as much to add the extra coat.

A general guide for the amount of paint needed for exteriors includes the following;

Exterior AreaPaint Quantity
Walls8 to 10 Gallons
Front Door¼ Gallon
Windows1 Gallon
Eave Linings w/Carport2 to 3 Gallons
Gutters, Fascia, etc.1 Gallon

Any additional areas that need painting will have to be accounted for as well.

To get a rough estimation of how much paint you will need to paint your house, you can also use an online paint calculator like this at thespruce.com or this one at sherwin-williams.com.


How Does A Paint Calculator Work?


Using online paint calculator or a paint estimator is one of the smartest and easiest ways to figure out how much paint you will need for your interior & exterior paint projects.

Remember that using these tools and calculators will give you a rough estimation and not the exact amount so you will need to buy the quantity based on this rough idea.

For estimating the paintable surface area, you can do a simple math (addition and multiplication).

  • Measure the length and the height of your walls in every room
  • Add together all the lengths and multiply the number by height of the room
  • The number you will get is a square footage of the paintable area

While getting the measurement, make sure you that you measure the length and height properly, especially when getting the height from the floor to the ceiling.

Alternatively, you can use a paint estimator to estimate the paint quantity and cost by simply filling in all the measurements.

The advantage of using these online paint calculators is it helps you to get the estimate when you do not want to paint the doors or windows.

You can simply fill in the measurements of your doors and windows and the calculator will help in subtracting the square footage areas of the windows and doors.

The paint quantity estimate you will get using these tools assumes that you will apply two coats of paint.

So, if you want to apply more than two coats you will need to add up to the quantity while buying from paint supply store.


How Much Does A Pint of Paint Cover?


How much area will a pint of paint cover, will depend on various factors like the paint quality, finish, number of coats, etc.

However, in general, I have found that:

  • 1 pint of paint will cover approximately about 50 square feet of area. These may like painting a dresser and two chairs.
  • 1 quart of paint can help you cover around 100-120 square feet of area. It’s like painting your bed, a dresser, and around three to four chairs.
  • 1 gallon of paint will be enough to cover your average-sized kitchen or a small kid’s bedroom (about 350-400 square feet area).

How Much Will It Cost to Paint an Entire House?


On average, people living in the US tend to be spending anywhere between $1500 to $3500 for a painting an entire house.

On the lower end of the spectrum, you will need to spend no less than $1000 if you have a low budget in mind.

No matter you want to paint your newly purchased house or need to repaint an old one for a newer look, the cost to paint your entire house will going to depend on lots of different factors.

These are like:

  • The size of your house,
  • Stories you have in your house,
  • Quality of paint you want to use,
  • The finishing and patterns you desire to have,
  • The choice of colors you have in mind for your interiors and exteriors,
  • Whether you will be using a professional painter or will paint your house yourself, etc.

If you really want to save on painting costs its essential to do your calculations right. You will need to calculate the cost of the paint job based on the per-gallon price.

Make sure that you do not buy too much paint for your house which will certainly save you much at the end.

Another way by which you can control the house painting cost is by doing the task yourself.

I don’t recommend this unless you are a passionate DIYer and know how to do the job right.

If not, you will end up creating a heavy mess that will eventually need lots of time and money to get cleared.


Things to Consider When Doing the Calculations


Remember that the measurements are based on a typical single-story house. You may need more if you have a larger home or less if you have a small house.

One way to alleviate the cost of having extra paint around is to purchase an excess liter or gallon and not have it tinted.

If you do not use it, then you can tint the paint the way you want for another need.

If it turns out you need the extra paint, then you can purchase the tint from the paint store and mix it in.

Knowing how much paint you need before you make the purchase may save you a considerable amount of money.

This is especially true if you are going with a higher-quality and thus, higher-priced paint.

The bottom line

Remember that there is no exact science to this, but overall you should err on the side of excess to ensure that you have enough paint to do the job.

It also helps if you have other uses for the leftover paint. This makes purchasing a little too much easier on your mind.

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