Buying paint should be exciting, not a guessing game involving tape measures, calculators and unnecessary math. So, how much paint do you actually need? 

As a general rule, one gallon of paint covers approximately 350–400 square feet for one coat. If you're painting two coats, plan on roughly 175–200 square feet of wall coverage per gallon. 

Of course, your exact paint needs depend on the size of your space, the number of coats, your wall texture, the color you're painting over and whether you need primer. Here's how to do the math and how to make sure you have enough paint before you get things rolling. 

The Rule of Thumb: What a Gallon of Paint Actually Covers 

For most interior walls, one gallon of our paint covers about 375-425 square feet with one coat. 

How Much Paint Do You Need by Room? 

The easiest way to estimate paint is square footage, but it helps to see what that looks like in real rooms. 

Bedroom 

A typical 12 × 12-foot bedroom with 8-foot ceilings has approximately 384 square feet of wall area before subtracting doors and windows. 

For one coat, you'd need roughly 1 gallon. For two coats, plan on 2 gallons. 

If your bedroom is larger, has taller ceilings or includes lots of wall space with few windows and doors, you'll need more.  

Living Room 

A 15 × 20-foot living room with 8-foot ceilings has approximately 560 square feet of wall area before subtracting doors and windows. 

That means you'll generally need: 

2 gallons for one coat 

2–3 gallons for two coats 

Large living rooms, open-concept spaces and rooms with vaulted ceilings can call for considerably more. 

Bathroom 

A 5 × 8-foot bathroom with 8-foot ceilings has approximately 208 square feet of wall area before subtracting doors, windows and other openings. 

For a bathroom this size, 1 gallon is typically enough for one or two coats, depending on the existing wall color and surface. 

Bathrooms can also have more interruptions like tile, mirrors, cabinets and fixtures, which reduce the amount of paintable wall space. 

Kitchen 

A 12 × 12-foot kitchen with 8-foot ceilings has approximately 384 square feet of wall area before subtracting windows, doors, cabinets and appliances. 

Because kitchens often have less exposed wall space than bedrooms or living rooms, 1–2 gallons may be enough for two coats in a typical kitchen. If you're painting cabinets, ceilings or other surfaces in addition to the walls, calculate those separately. 

Whole Home 

Painting an entire home? We love that! Start with the total paintable wall area rather than simply adding up room dimensions. 

As a very rough starting point, a 1,500-square-foot home may require around 4–6 gallons per coat for walls, depending on ceiling height, layout, windows, doors and how much wall space is actually exposed. 

For two coats, that could mean approximately 8–12 gallons. For a more accurate number, measure each room individually or let the our Paint Calculator do the math for you. 

The Variables That Change the Math 

Your room's square footage is only part of the equation. These factors can increase or decrease how much paint you'll need. 

Number of Coats 

The biggest variable is simple: more coats = more paint. 

If one gallon covers 375-425 square feet with one coat, that same gallon covers approximately 175–200 square feet when you're applying two coats. 

So if your walls have 700 square feet of paintable area: 

One coat = approximately 2 gallons 

Two coats = approximately 4 gallons 

Always account for the number of coats when calculating your total. 

Wall Texture and Condition 

Smooth walls generally use less paint than heavily textured or porous surfaces. 

Texture creates more surface area for the paint to cover, while damaged, unsealed or very porous walls can absorb more paint than expected. 

If your walls are in rough shape, patching and priming before painting can help create a more uniform surface and improve the final result. 

Going Dark to Light 

Making a dramatic color change? Going from a deep, saturated color to a much lighter shade can require additional coverage. 

For example, painting a bright white over a deep navy is a bigger color transition than painting a soft beige over an existing light neutral. 

In these situations, primer can help create a more consistent base, which may reduce the amount of finish paint needed to achieve an even result. 

When You Need Primer 

Primer isn't always necessary, but it can be especially helpful when you're: 

• Painting over a very dark or dramatic color
• Painting new, unpainted drywall
• Covering stains or repairs
• Painting a porous or uneven surface
• Making a significant color change 

Starting with a properly prepared surface can help your paint apply more evenly and cover more consistently. 

Do You Need One Coat or Two? 

Most interior painting projects should be planned for two coats. One coat may be enough when you're making a subtle color change over a smooth, well-prepared surface and the paint has excellent coverage. But two coats generally provide more consistent color, sheen and coverage. 

If you're painting a new color over an existing color, two coats are often the safer bet. 

And remember: two coats doesn't necessarily mean your project will use twice as much paint if the first coat provides excellent coverage. A well-covering paint can help you achieve the finished look with fewer coats, which means less paint used overall. 

How to Calculate Exactly How Much Paint You Need 

Ready to stop guessing? 

Using the Paint Calculator 

The easiest way to get a more precise estimate is to use our Paint Calculator. Enter your room dimensions and project details to get an estimate based on the space you're actually painting. 

It's especially helpful if you're painting multiple rooms, have different ceiling heights or want to account for doors and windows. 

Pro tip: It's better to have a little leftover paint than to run out halfway through your final coat. Keep a small amount stored away for future touch-ups, too. 

How Better Coverage Can Mean Less Paint Overall 

Coverage isn't just about how many square feet a gallon can technically cover. How well the paint covers can affect how many coats you ultimately need. A paint with strong coverage may help you achieve an even, finished look in fewer coats. Fewer coats can mean less paint, less time spent painting, and fewer trips back to the store. 

In other words: don't only ask, "How many gallons do I need?" Also ask, "How many coats will I need?" That's where choosing a quality paint can make a difference. 

Common Questions About Paint Coverage 

How Much Paint Do I Need for a 12x12 Room? 

A 12 × 12-foot room with 8-foot ceilings has approximately 384 square feet of wall area before subtracting doors and windows. As a general estimate, you'll need about 1 gallon for one coat or 2 gallons for two coats. Your exact amount will vary based on the number and size of doors and windows, ceiling height, wall condition and existing color. 

Does a Gallon of Paint Cover a Room in One Coat? 

It depends on the size of the room. A smaller bedroom or bathroom may fall within the range of 375-425 square feet, while a large living room may require two gallons or more. 

How Much Paint Do I Need for Two Coats? 

For two coats, divide the approximate one-coat coverage in half. One gallon covers approximately 175–200 square feet for two coats. So, if you have 400 square feet of paintable wall area, plan on approximately 2 gallons for two coats. 

How Do I Calculate How Much Paint I Need? 

To estimate your paint needs: 

• Measure the length of each wall.
• Measure the ceiling height.
• Multiply wall length × ceiling height to calculate each wall's square footage.
• Add the walls together.
• Subtract large doors and windows.
• Divide your total paintable area by approximately 350–400 square feet per gallon for one coat.
• Multiply by the number of coats you'll apply. 

For the easiest estimate, and a sigh of relief, plug your measurements into our Paint Calculator. 

Do I Need More Paint if I'm Going From Dark to Light? 

You might. Dark-to-light color changes can require additional coverage, particularly if the existing color is very saturated or the surface isn't properly prepared. Using primer can help create a more uniform base before applying your lighter finish color. Depending on the starting color and the new color, you may also need two finish coats. 

Get an Exact Number Before You Order 

There's no reason to play paint-guessing roulette. 

Start with the rule of thumb: one gallon covers roughly 375-425 square feet for one coat, then factor in your room size, number of coats, wall condition and color change. 

For the most accurate estimate, use the our Paint Calculator before you order. It takes the guesswork out of figuring out how much paint you'll need, so you can spend less time doing math and more time making your space look very, very good. 

Keep reading: 

• How to Paint a Room: Clare's Ultimate Guide 
• A Cleaner, Smarter Way to Test Paint at Home
• Your Guide To Paint Finishes That Look Good and Hold Up