Paint Calculator: How Much Paint Do You Really Need?

Planning a painting project?

One of the trickiest parts is figuring out how much paint you really need. That’s where a paint calculator comes in. Instead of guessing and hoping a gallon will stretch across three rooms, you can plug in a few numbers and get a solid estimate right away.

This tool is especially helpful if you’re painting multiple rooms, switching colors, or adding a fresh coat to your kitchen, bathroom, or bedroom. And with paint prices what they are, nobody wants to waste a drop.

The paint calculator simplifies the math. You don’t need to be a contractor or math wiz to use it. If you can measure a wall and count how many windows and doors you have, you’re already halfway there.

Key Takeaways:

• A paint calculator helps avoid overbuying or running out of paint mid-project.
• Measurements should include wall height, length, and account for doors and windows.
• Most walls need two coats for better coverage and finish.
• Ceilings, textured surfaces, and porous materials often need more paint.
• The right paint estimate can save time, money, and stress.

The paint calculator takes your room measurements and tells you how many gallons (or quarts) of paint you’ll need. It uses a standard formula based on square footage, assuming one gallon of paint covers roughly 350 square feet.

It also factors in:

• The number of coats you plan to apply
• Whether you’re painting the ceiling

How many windows and doors you have, so it subtracts areas that don’t need paint

Before you begin, grab a tape measure and follow these steps:

1. Choose your room shape

Most rooms are rectangles or squares. If your room is L-shaped or has more walls, choose the custom option.

2. Measure the walls

Measure each wall’s length and height in feet or inches. You can add walls individually to get the full square footage.

3. Subtract windows and doors

Enter how many windows and doors the room has. The calculator subtracts their area from the total.

4. Decide if you want to paint the ceiling.

Painting the ceiling? Enter the length and width to calculate its surface area.

5. Select the number of coats

Most walls need at least two coats. You can adjust this if you’re doing a primer coat first or repainting in the same color.

6. Get your estimate

Once all your info is in, the paint calculator will tell you how many gallons or quarts you need to cover the space.

Let’s break it down by room. Different spaces need different approaches, depending on the layout, lighting, surface, and even the type of paint you’re using.

Living rooms usually have large open walls, and sometimes tall ceilings. They’re also where color choices make a big impact. If you’re painting over a dark wall, make sure to count two full coats—plus primer if you’re switching to a lighter shade.

Think about the windows too. A big front window might save you paint, but you’ll still want enough for touch-ups or wood trim.

Bedrooms tend to be smaller than living spaces, but they might still need more paint than expected, especially if you’re painting closets and ceilings.

If your walls have texture, you may need more paint for proper adhesion. This is also a great time to explore different finishes. If you’re unsure, here’s a link on different paint sheens that might help you decide.

Kitchens can be tricky. You’ve got appliances, tile, cabinets, and often a mix of wall sizes. If you’re painting around windows, cabinets, or a backsplash, your paintable area is smaller—but the surfaces may need extra prep.

Also, consider using a higher gloss or semi-gloss interior paint for easier cleaning. And if you’re painting cabinets, remember that a primer is usually necessary. For more on that, check out how many coats of primer do I need.

Bathrooms are humid, so always go with a paint that resists mildew and moisture. If you’re working around a vanity, mirror, or tile, measure only the parts you’ll actually paint.

And if you’re covering old wood trim or plaster, sand the area first so your new paint sticks. Don’t forget the ceiling if you’re doing a full refresh.

A lot of people skip the ceiling, but it’s one of the quickest ways to brighten a room. Flat white paint is typical, but if you’re changing colors or covering stain, you’ll need more coverage.

Measure length x width for each ceiling, then decide how many coats. Two coats are common, especially in older homes where stains or smoke marks are present.

• When painting concrete, brick, or porous surfaces, buy extra. These materials absorb more paint.
• Always measure in feet or meters, then multiply length by height to get square footage.
• Factor in flooring, furniture, and prep time when scheduling your project.
• Use quality brushes and tools for better application and fewer coats.

Not sure if your wall color is an exact match? This article on how to match paint color already on wall can help you double-check before starting.

The paint calculator is a small step that makes a big difference in planning any painting job. It takes into account all the key measurements—wall dimensions, square footage, windows, and coats—to give you a close estimate of how much paint to buy. It’s faster, easier, and more accurate than winging it.

Whether you’re painting a bedroom, freshening up a kitchen, or giving your bathroom a full makeover, starting with the right amount of paint sets the tone for a smoother project. It’s one less thing to second-guess.

Here’s how we help make it even easier:

• Accurate measurements and paint estimates based on your room and surface
• Free color consultations to choose the right finish and shade
• Clean, respectful prep and protection for your floor, furniture, and interior spaces
• Experienced, certified painters who know their craft
• Flexible scheduling and clear daily communication

Need help figuring out your next paint project?

Contact A New View Painting for a FREE estimate in Erie, Broomfield, Lafayette, CO and the surrounding areas.

Call us at 970-660-3993 and let’s make your home feel like new again—one coat at a time!