Paint Cost Calculator
Instantly estimate exactly how many gallons of paint you need and the total cost for your next interior or exterior painting project.
Whether you are planning to refresh a single bedroom or paint the entire exterior of your house, buying the right amount of paint is essential. Buy too little, and you have to stop your project midway to run to the hardware store. Buy too much, and you waste money on heavy cans that sit in your garage for years.
Our paint cost calculator eliminates the guesswork. By entering your room dimensions or total square footage, it automatically subtracts non-paintable areas like doors and windows, factors in your desired number of coats, and calculates the exact number of gallons you need to purchase alongside an estimated material cost.
How to Calculate Paint Cost and Quantity
To accurately estimate your paint needs, you must find the net paintable surface area and divide it by the paint’s coverage rate. Here is the step-by-step mathematical process:
- Find Total Wall Area: If measuring a room, multiply the length by the height, and multiply the width by the height. Add those numbers together, and multiply by 2 (for opposite walls).
Area = (Length × Height × 2) + (Width × Height × 2) - Subtract Obstacles: Subtract the square footage of any doors, windows, or large unpaintable built-ins to find the Net Paintable Area.
- Multiply by Coats: Multiply the Net Paintable Area by the number of coats you intend to apply (usually 2). This gives you the Total Coverage Area.
- Calculate Gallons: Divide the Total Coverage Area by the coverage rate of your specific paint (typically 350 sq ft per gallon).
- Calculate Cost: Round up your calculated gallons to the next whole number (since you buy paint by the gallon) and multiply by the price per gallon.
Gallons = ((Net Area × Coats) ÷ Coverage Rate)
Round the result UP to know how many actual cans to purchase at the store.
How Much Paint Do I Need? (Coverage Rates)
A frequent question is: “How much paint is for 1 sq ft?” To answer that, you need to understand the standard coverage rates of architectural paints.
A standard 1-gallon can of interior acrylic latex paint covers roughly 350 to 400 square feet for a single coat on a smooth surface. This means 1 square foot requires approximately 0.0025 to 0.0028 gallons of paint.
- Smooth Drywall: ~350 – 400 sq ft per gallon.
- Textured Walls or Stucco: ~250 – 300 sq ft per gallon (texture dramatically increases surface area).
- Bare, Unprimed Drywall: The first coat will soak in heavily, often yielding only ~200 – 250 sq ft per gallon. Always use a dedicated primer on new drywall first.
Never Plan for Just One Coat
Unless you are painting over a wall with the exact same color and sheen, you should always calculate your material based on two coats. Even premium “paint and primer in one” products rarely provide flawless coverage in a single pass over a contrasting color.
Standard Deductions for Doors and Windows
You don’t paint over glass or standard wooden doors when painting a wall. Professional painters use standard industry averages to deduct these areas quickly without needing to measure every single frame.
| Feature | Standard Deduction Area |
|---|---|
| Standard Interior Door | Subtract 21 square feet |
| Standard Window | Subtract 15 square feet |
| Sliding Glass Door | Subtract 40 square feet |
Paint Cost Estimator: Average Prices
If you are trying to estimate paint cost, the price per gallon varies wildly based on brand, quality, and sheen. A flat builder-grade paint might cost $20, while a premium washable matte from Sherwin Williams or Benjamin Moore can exceed $80 a gallon.
- Economy / Contractor Grade: $20 – $30 per gallon. (Good for flips, but often requires more coats).
- Standard Mid-Tier: $35 – $55 per gallon. (The sweet spot for most homeowners).
- Premium / Designer: $60 – $90+ per gallon. (Excellent durability, scrubbability, and rich pigments).
Worked Examples (12×12 Room & 1000 sq ft)
Example 1: Painting a 12×12 Room
“Will 1 gallon of paint cover a 12×12 room?” Let’s do the math for a standard 12 ft by 12 ft room with an 8 ft ceiling, 1 door, and 2 windows.
- Total Wall Area: (12×8×2) + (12×8×2) = 384 sq ft.
- Deductions: 1 door (21) + 2 windows (30) = 51 sq ft.
- Net Paintable Area: 384 – 51 = 333 sq ft.
A single gallon covers up to 400 sq ft, so 1 gallon will barely cover one coat. Because you need two coats for a proper finish, your Total Coverage Area is 666 sq ft. Therefore, you must buy 2 gallons. At $45 a gallon, the material cost is $90.
Example 2: How much should it cost to paint 1000 sq ft?
If you have exactly 1,000 net square feet of wall space to paint with 2 coats:
- Total Coverage Area = 1,000 × 2 = 2,000 sq ft.
- Gallons = 2,000 ÷ 350 = 5.71 gallons.
- You need to buy 6 gallons of paint.
At $50 per gallon, your DIY material cost is $300. If you are hiring a professional painter, labor typically costs $1.50 to $3.00 per square foot of floor space, bringing the total estimated cost to $1,500 – $3,000+.
Paint Cost Calculator Frequently Asked Questions
To paint 1000 sq ft of wall space with two coats, you need about 6 gallons of paint. If paint costs $45 per gallon, the DIY material cost is roughly $270. If hiring a professional, expect to pay between $1,500 and $3,000 total including labor and materials.
A standard gallon of interior paint covers roughly 350 to 400 square feet for a single coat. Therefore, 1 square foot requires approximately 0.0025 to 0.0028 gallons of paint per coat.
Calculate your total wall area, subtract the area for doors (approx. 21 sq ft each) and windows (approx. 15 sq ft each). Multiply that net area by the number of coats (usually 2), then divide by the paint’s coverage rate (usually 350 sq ft/gal) to find the total gallons.
Determine the total gallons needed for your project and round up to the nearest whole gallon (since you must buy full cans). Multiply that whole number by the price per gallon of your chosen paint brand to get the estimated cost.
Painting the interior of a 2000 sq ft house usually requires 12 to 15 gallons of paint for the walls. The DIY material cost is typically $600 to $1,000. Hiring a professional painter usually costs between $3,500 and $7,000 depending on your region.
A 12×12 room has about 384 sq ft of wall space. A professional painter typically charges between $300 and $800 to paint a room of this size, which usually includes the cost of basic paint, prep work, and two coats on the walls.
Professional painters generally charge between $40 and $80 per hour, which equates to $320 to $640 per day per painter. Costs vary significantly based on your location, the painter’s experience, and whether they operate independently or for a larger company.
One gallon of paint covers up to 400 sq ft. A standard 12×12 room with 8-foot ceilings has about 384 sq ft of wall area. So, 1 gallon will barely cover one coat. For a proper finish, you need two coats, meaning you must buy 2 gallons.
Reference: https://en.wikipedia.org/wiki/Paint