Paint Coverage Calculator
Wondering “how much paint do I need?” Use our paint calculator to estimate the exact number of gallons and quarts required for your interior walls, ceilings, or exterior house projects based on total square feet.
Room Dimensions
Enter your room dimensions to estimate your paint needs.
Total Paintable Area
How to Calculate How Much Paint I Need
Whether you’re using our paint calculator for walls or tackling an exterior house painting project, knowing exactly how to calculate paint needed is critical. Buying too much paint wastes money, but stopping midway to buy more runs the risk of mismatched dye lots.
- Measure the Room: Find the length and width of the floor, plus the height of the walls.
- Deduct Openings: A standard door takes up about 21 square feet, and a standard window removes about 15 square feet of paintable space.
- Determine Coats: We always recommend a paint calculator interior setting of 2 coats for an even, durable finish.
- Calculate: The tool runs the math to find your paint coverage per square foot and tells you exactly how many gallons and quarts to buy.
The Paint Calculation Formula
If you want to manually run a paint calculation formula, it involves finding the perimeter of the room and multiplying it by the height to find the total square footage.
Mathematical Formula
Gallons Needed = (Total Area × Number of Coats) / Coverage per Gallon
Note: Standard coverage is roughly 350-400 sq ft per gallon.
Worked Example: Paint Calculator for a 12×12 Room
Let’s ask: How much paint is needed for a 12×12 room? Assuming an 8-foot ceiling, one door, and one window.
- Perimeter: (12 + 12) × 2 = 48 feet
- Wall Area: 48 × 8 (height) = 384 sq ft
- Deductions: 384 – 21 (door) – 15 (window) = 348 sq ft
With a standard 1 gallon of paint coverage yielding 350 sq ft, you would need exactly 1 gallon for a single coat, or 2 gallons for two coats.
Paint Coverage by Container Size
Brands like Menards paint, Behr, and Sherwin-Williams generally follow standard yield metrics. Here is a quick reference table for paint coverage per gallon and paint coverage per quart.
| Container Size | Coverage Area (1 Coat) | Best Used For |
|---|---|---|
| 1 Quart (32 oz) | 87 – 100 sq ft | Trim, doors, small touch-ups, accent furniture. |
| 1 Gallon | 350 – 400 sq ft | Standard bedrooms, small living rooms, ceilings. |
| 5 Gallon Pail | 1,750 – 2,000 sq ft | Exterior house paint, whole-home interior repaints. |
Average Room Sizes and Paint Needed (2 Coats)
| Room Dimensions | Approx. Paintable Area | Paint Required (2 Coats) |
|---|---|---|
| 10 x 10 feet | 284 sq ft | 2 Gallons |
| 10 x 12 feet | 316 sq ft | 2 Gallons |
| 12 x 12 feet | 348 sq ft | 2 Gallons |
| 15 x 20 feet (Large Living) | 524 sq ft | 3 Gallons |
Frequently Asked Questions
How much will 1 gallon of paint cover?
Under standard conditions, 1 gallon of paint will cover about 350 to 400 square feet for a single coat. If you are painting highly textured walls, bare unprimed drywall, or using a masonry exterior paint calculator, expect the coverage to drop to 250-300 square feet per gallon.
How many gallons of paint for 2000 sq ft house exterior?
To calculate exterior paint for a 2,000 sq ft home, you have 2,000 sq ft of surface area. Two coats require enough paint for 4,000 sq ft. Divide 4,000 by 350 (average exterior paint coverage per gallon), and you will need approximately 11.5 to 12 gallons. Always buy 12 to 14 gallons to account for waste and textured siding.
What is the average cost to paint a 1700 sq ft house?
If you use an exterior paint estimate calculator to do it yourself, materials (paint, primer, brushes, tape) will cost roughly $500 to $1,000. Hiring professional painters to do the exterior of a 1,700 sq ft house typically costs between $2,500 and $5,000 depending on your region and the home’s condition.
Will 1 gallon of paint cover a 10×10 room?
Yes and no. A standard 10×10 room with 8-foot ceilings has about 284 square feet of wall space (after subtracting a door and window). 1 gallon of paint coverage is 350 sq ft, so 1 gallon will cover one coat. Because you almost always need two coats, you should buy 2 gallons.
What is the hardest color to paint over?
Red, black, and dark navy blue are notorious for being the hardest colors to paint over. When using a room paint calculator for these transitions, you must factor in a high-quality tinted primer and at least 2 to 3 topcoats, increasing your required paint volume.
How many hours to paint a 10×10 room?
For an average DIYer, prep work (taping, laying drop cloths, patching holes) takes about 1-2 hours. Cutting in edges takes 1 hour per coat, and rolling takes 30-45 minutes per coat. Expect to spend 4 to 6 hours of active working time, plus drying time between coats.
Do professional painters do walls or trim first?
Most professionals paint the trim first, allow it to dry completely (often 24 hours), tape off the trim, and then paint the walls. Trim paint is glossier and harder to touch up, so it’s easier to overlap wall paint onto the trim line than vice versa.
How much deck paint do I need?
A deck paint coverage per gallon is typically lower than interior paint because wood is porous. Expect about 200 to 300 square feet per gallon. For a 20×20 foot deck (400 sq ft), you will need about 2 gallons for the first coat, and 1.5 gallons for the second coat (buy 4 gallons total).
How much does a qt of paint cover?
A quart of paint coverage (32 ounces) will cover roughly 85 to 100 square feet. This is ideal for a ceiling paint calculator on a tiny bathroom, or for painting interior doors, trim, and baseboards.
How often should rooms in a house be painted?
High-traffic areas like hallways, kitchens, and living rooms should be repainted every 3 to 5 years. Bedrooms and dining rooms can usually go 5 to 7 years. Ceiling paint coverage lasts the longest and generally only needs repainting every 10 years unless there is water damage or smoke.
Disclaimer: This paint amount calculator provides estimates based on standard industry coverage yields (350 sq ft/gallon). Highly porous surfaces like stucco, bare drywall, and rough wood will require more paint. Always consult the manufacturer’s label (e.g., Behr paint coverage or Home Depot paint calculator guides) for specific product yields.
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Reference: https://en.wikipedia.org/wiki/Paint