How many square feet does a gallon of paint cover?

For interior latex, about 350 to 400 square feet per gallon.

Do I need to account for multiple coats?

Yes. Most projects need two coats. The calculator above includes a coat setting for this.

Does wall texture affect how much paint I need?

Yes. Textured walls absorb more paint. Expect coverage at the lower end of the range (around 350 sq ft per gallon).

How much paint for a 12x12 room?

Use the calculator with your room's height. A typical 12x12 room with 8-foot ceilings needs about 1.5 to 2 gallons for two coats.

Can I use exterior paint indoors?

Not recommended. Exterior paints have different additives and fumes. Stick to interior latex for inside walls.

What if I'm painting over a dark color?

You might need three coats or a primer first. The calculator has an option for color change.

How much primer do I need?

Primer covers about 300 to 350 square feet per gallon. One coat is usually enough.

Should I buy extra paint for touch-ups?

Yes. Get one quart extra for future touch-ups, especially if you're using a custom color.

Is this calculator accurate for irregular rooms?

It's best for standard rectangular rooms. For L-shaped or irregular spaces, measure each section separately and add the totals.

What's the most common mistake people make?

They forget to subtract windows and doors. The calculator does this for you.

How Much Paint Do I Need?

Know how much paint you need before you open a single can.

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Stop Wasting Money on Extra Paint

📊 Data sourced from publicly available industry standards. See our methodology page for formulas, sources, and limitations.

You've been there. You buy what you think is enough paint. Then you're either scrambling for one more gallon mid-project or staring at five full cans you'll never use. I've made that mistake myself—when I moved last year, I ended up with three extra gallons of a color I'll never touch again. This page fixes that. Use the calculator below to get your exact paint estimate. It accounts for multiple coats and wall texture, two things most calculators ignore.

How Much Paint Do You Actually Need?

Let's break it down. A gallon of interior latex paint typically covers between 350 and 400 square feet. For most rooms, that's enough for one coat on a standard wall. But here's the thing—you almost always need two coats. And if your walls are textured? That coverage drops to the lower end. Honestly, this calculator won't work perfectly if your walls are heavily textured like popcorn or knockdown. For those, you'll want to add about 20% more paint. The tool above already accounts for this if you select the texture option. For a typical 12x15 foot bedroom with 8.5-foot ceilings, you're looking at roughly two gallons for two coats. But don't take my word for it—run the calculator with your exact numbers.

Paint Coverage by Type

Here are the standard coverage rates used by the calculator. These come from manufacturer data.

What Affects Your Paint Total?

A few things can throw off your estimate. Wall texture is the big one—smooth walls use less paint. Then there's color change. If you're going from dark to light, you might need three coats instead of two. The calculator has a setting for that. Also, don't forget windows and doors. The tool subtracts their area automatically, but if you're measuring by hand, each standard window saves you about 15 square feet, and each door saves about 20. In my experience, people forget to account for ceilings. If you're painting the ceiling too, add a separate calculation for that—ceilings take about the same coverage as walls.

Paint Price Ranges: What to Expect

Paint prices vary a lot. A gallon can cost anywhere from $15 to $70. The typical gallon sits around $35. For a standard bedroom needing two gallons, you're looking at $70 for mid-range paint. Higher-end paints like Sherwin-Williams or Benjamin Moore can push that to $140. The calculator doesn't factor in price, but use the gallon count it gives you and multiply by your preferred brand's cost per gallon.

Your Next Steps

First, use the calculator above with your room's exact dimensions. Second, decide on your paint type—interior latex for most indoor jobs. Third, buy one extra quart for touch-ups later. That's a pro tip I picked up from a contractor friend. Don't buy extra gallons unless you're painting a large area. And remember, primer is separate—if you're painting bare drywall or a dark color, you'll need a gallon of primer too.

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CoverWise Pick: Sherwin-Williams Duration Interior Paint

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Frequently Asked Questions

How many square feet does a gallon of paint cover?: For interior latex, about 350 to 400 square feet per gallon.
Do I need to account for multiple coats?: Yes. Most projects need two coats. The calculator above includes a coat setting for this.
Does wall texture affect how much paint I need?: Yes. Textured walls absorb more paint. Expect coverage at the lower end of the range (around 350 sq ft per gallon).
How much paint for a 12x12 room?: Use the calculator with your room's height. A typical 12x12 room with 8-foot ceilings needs about 1.5 to 2 gallons for two coats.
Can I use exterior paint indoors?: Not recommended. Exterior paints have different additives and fumes. Stick to interior latex for inside walls.
What if I'm painting over a dark color?: You might need three coats or a primer first. The calculator has an option for color change.

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