Paint Calculator

🎨 Paint Finish Guide

Finish	Best For	Sheen
Flat / Matte	Ceilings, low-traffic rooms	0–5%
Eggshell	Living rooms, bedrooms	10–25%
Satin	Kitchens, bathrooms, hallways	25–35%
Semi-Gloss	Trim, doors, cabinets	35–70%
High-Gloss	Accent pieces, furniture	70–90%

💰 Paint Costs (2026)

Budget (e.g., Behr Ultra): $25–$35/gal
Mid-range (e.g., Benjamin Moore Regal): $45–$65/gal
Premium (e.g., Farrow & Ball): $80–$110/gal
Primer: $15–$30/gal
Ceiling paint: $20–$40/gal
Pro labor: $2–$6/sq ft

🛒 Paint Buying Tips

Buy all your paint at once — batch colors can vary slightly
Keep 1 quart for touch-ups (label with room and date)
Round up to the next full gallon — running short mid-wall causes visible lap marks
Test a sample quart on the wall before committing — colors look different in your lighting
Higher-quality paint covers better, lasts longer, and often needs fewer coats

🖌️ Coverage Factors

Smooth drywall: 350–400 sq ft/gal
Textured walls: 250–300 sq ft/gal
Bare wood/drywall: 250–350 sq ft/gal
Brick / masonry: 150–250 sq ft/gal
Spraying: Uses 20–30% more paint than rolling

Darker colors over light backgrounds and vice-versa may need an extra coat.

How to Calculate Paint for a Room

Figuring out how much paint you need is straightforward once you know the formula. Here's how professionals estimate paint quantities for any room size, shape, or finish.

Step 1: Measure Your Walls

Measure the length of each wall and the ceiling height. Multiply the perimeter of the room (length + width + length + width) by the wall height. This gives you the total wall area in square feet. For example, a 12×14-foot room with 8-foot ceilings has a perimeter of 52 feet and a total wall area of 416 square feet.

Step 2: Subtract Doors and Windows

A standard interior door is about 21 square feet (3×7 ft). A typical window is about 15 square feet (3×5 ft). Subtract these from your total wall area. Our calculator does this automatically — just enter the count of doors and windows.

Step 3: Factor in Coats

Most paint jobs need two coats for solid, even coverage. If you're painting over a similar color with premium paint, one coat may suffice. Dark-to-light or light-to-dark color changes usually require a primer coat plus two finish coats. Multiply your paintable area by the number of coats to get the total coverage needed.

Step 4: Divide by Coverage Rate

A gallon of interior latex paint covers approximately 350 square feet on smooth walls. Divide your total coverage area by 350 to get the gallons needed. Always round up — running out of paint mid-wall can leave visible lines where you stopped.

When to Use Primer

Primer is essential when painting new drywall, covering stains, switching from oil-based to latex paint, or making dramatic color changes. Tinted primer (tinted to match your finish color) reduces the number of finish coats needed. For most repainting jobs on previously painted walls, a quality paint-and-primer-in-one product works well.

How Much Paint for Common Room Sizes?

Quick reference for interior wall paint (2 coats, 350 sq ft/gallon coverage):

Room Size	Wall Area (approx.)	Gallons (2 coats)	Cost (premium paint)
Bathroom (5×8, 8ft ceiling)	~180 sq ft	~1 gallon	$30–$60
Bedroom (10×12)	~350 sq ft	~2 gallons	$60–$120
Living room (14×18)	~510 sq ft	~3 gallons	$90–$180
Master bedroom (16×20)	~575 sq ft	~3.5 gallons	$105–$210
Whole apartment (800 sq ft)	~1,800 sq ft	~10 gallons	$300–$600
Whole house (1,500 sq ft)	~3,400 sq ft	~20 gallons	$600–$1,200
Whole house (2,500 sq ft)	~5,600 sq ft	~32 gallons	$960–$1,920

Wall area ≈ perimeter × ceiling height minus doors/windows (~20 sq ft each). Premium paint: 350–400 sq ft/gal; economy: 250–300.

Frequently Asked Questions

How much paint do I need for a 12×12 room?

A 12×12 room with 8-foot ceilings has about 384 sq ft of wall area. After subtracting a door (~21 sq ft) and two windows (~30 sq ft), you have roughly 333 sq ft. At 350 sq ft per gallon, one gallon covers one coat. For two coats, buy 2 gallons. If you're changing colors dramatically, you may need primer plus 2 coats of paint (3 gallons total).

Do I need primer before painting?

Yes, use primer when painting over dark colors, covering stains, painting bare drywall, or switching between paint types (oil to latex). Modern paint-and-primer combos work well for simple color refreshes on previously painted walls. Tinted primer is recommended when making dramatic color changes — it can save you an entire finish coat.

What is the best paint finish for each room?

Flat/matte is ideal for ceilings and low-traffic rooms — it hides imperfections. Eggshell is the most popular finish for living rooms and bedrooms, offering a soft sheen with light washability. Satin works best in kitchens, bathrooms, and hallways due to its moisture resistance. Semi-gloss is perfect for trim, doors, and cabinets. High-gloss is used for accent pieces and furniture.

How much does a gallon of paint cover?

A gallon of paint typically covers 350–400 sq ft on smooth, previously painted surfaces. Rough or textured walls may only get 250–300 sq ft per gallon. Coverage also depends on the paint quality, the color change, and whether you're applying it with a roller (best coverage), brush, or sprayer (uses 20–30% more).

Should I paint the ceiling the same color as the walls?

Most designers recommend painting ceilings flat white or a shade lighter than the walls. This makes rooms feel taller and brighter. Use flat or matte finish on ceilings to hide imperfections — sheen catches the light and highlights every bump. For a dramatic or cozy effect, painting the ceiling a darker color can work in larger rooms with high ceilings.

How much paint do I need for a 1,500 sq ft house?

~3,400 sq ft of walls. With 2 coats at 350 sq ft/gal = ~20 gallons (5 five-gallon buckets). Budget $600–$1,200 for premium paint.

How many gallons of paint for a 12×12 room?

~384 sq ft walls minus ~40 sq ft openings = 344 sq ft. With 2 coats at 350 sq ft/gal = ~2 gallons. Buy an extra gallon if covering a dark color.

How much does it cost to paint a room yourself?

DIY 12×14 bedroom: ~$80–$200 (2 gallons paint $60–$120, roller set $15, tape $10, drop cloth $10). Hiring a pro: $300–$800/room. DIY saves 60–75%.

How Much Paint for Any Home Project?

How much paint for a 10×10 room? A 10×10 room with 8 ft ceilings has ~280 sq ft of wall area (after subtracting one door). With 2 coats at 350 sq ft/gal, you need about 1.6 gallons — so buy 2 gallons.

How much paint for the exterior of a house? Multiply the home's footprint perimeter × wall height. A 1,500 sq ft single-story home has ~140 linear ft of walls × 9 ft = ~1,260 sq ft. With 2 coats: ~7–8 gallons of exterior paint. Budget $300–$500 for premium exterior paint.

What's the best paint for bathrooms? Use semi-gloss or satin finish — they resist moisture and are easy to clean. Expect to pay $40–$70/gallon for moisture-resistant bathroom paint from brands like Benjamin Moore or Sherwin-Williams.

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