Sherwin-Williams Paint Calculator
Estimate the right amount of paint for your project.
Measure the perimeter of the room. For a 12′ x 13′ room, the total length is (12+13)*2 = 50 ft.
Measure from the floor to the ceiling. The standard is 8 ft.
Standard doors are about 21 sq ft (2 sq m).
Standard windows are about 15 sq ft (1.4 sq m).
Two coats are recommended for best coverage and color richness. More for drastic color changes.
Most Sherwin-Williams paints cover 350-400 sq ft per gallon. Check the can for specifics.
Paint Breakdown (Gallons)
What is a Sherwin-Williams Paint Calculator?
A Sherwin-Williams paint calculator is a specialized tool designed to eliminate the guesswork from one of the most crucial parts of any painting project: buying the right amount of paint. Instead of buying too much and wasting money, or too little and having to make an inconvenient trip back to the store, this calculator provides a reliable estimate. By inputting your room’s dimensions, the number of doors and windows, and desired coats, you get a scientific approximation of your needs, specifically tailored to the high-quality coverage you expect from Sherwin-Williams products. This tool is essential for both DIY homeowners and professional painters who value efficiency and accuracy. Knowing how to paint a room starts with knowing how much paint you need.
Paint Coverage Formula and Explanation
The calculation is based on a straightforward area-based formula. The tool first determines the total surface area of your walls and then subtracts the areas that don’t need paint, like doors and windows. Finally, it accounts for the number of coats and the specific coverage rate of your chosen paint.
The basic formula is:
Gallons Needed = ((Total Wall Area – Deductions) * Number of Coats) / Coverage Per Gallon
| Variable | Meaning | Unit (Default) | Typical Range |
|---|---|---|---|
| Total Wall Area | The gross surface area of all walls to be painted (Length x Height). | Square Feet (sq ft) | 100 – 1000+ |
| Deductions | The combined area of doors and windows that will not be painted. | Square Feet (sq ft) | 20 – 200 |
| Number of Coats | How many layers of paint will be applied. | Unitless | 1 – 3 |
| Coverage Per Gallon | The area a single gallon of paint can cover, as specified by the manufacturer. | Square Feet (sq ft) | 350 – 400 |
Practical Examples
Example 1: Standard Bedroom
Let’s calculate the paint needed for a master bedroom with walls totaling 54 feet in length and a standard height of 8 feet. The room has one door and three windows.
- Inputs:
- Total Wall Length: 54 ft
- Wall Height: 8 ft
- Doors: 1, Windows: 3
- Coats: 2
- Coverage: 400 sq ft/gallon
- Results:
- Total Wall Area: 54 * 8 = 432 sq ft
- Deductions: (1 * 21) + (3 * 15) = 66 sq ft
- Paintable Area: 432 – 66 = 366 sq ft
- Total Paint Needed: (366 * 2) / 400 = 1.83 gallons. You should purchase 2 gallons.
Example 2: Living Room with High Ceilings (Metric)
Consider a living room with a total wall length of 20 meters and a height of 3 meters. It has two doors and four large windows.
- Inputs:
- Total Wall Length: 20 m
- Wall Height: 3 m
- Doors: 2, Windows: 4
- Coats: 2
- Coverage: 37 sq m/gallon (approx. 400 sq ft)
- Results:
- Total Wall Area: 20 * 3 = 60 sq m
- Deductions: (2 * 2) + (4 * 1.4) = 9.6 sq m
- Paintable Area: 60 – 9.6 = 50.4 sq m
- Total Paint Needed: (50.4 * 2) / 37 = 2.72 gallons. You should purchase 3 gallons.
How to Use This Sherwin-Williams Paint Calculator
- Select Your Units: Start by choosing between ‘Feet (ft)’ or ‘Meters (m)’. The labels will update accordingly.
- Measure Your Walls: Use a tape measure to find the length of each wall you plan to paint. Add these lengths together and enter the total in the ‘Total Wall Length’ field. Then, measure the height from floor to ceiling and enter it.
- Count Doors and Windows: Count the number of standard-sized doors and windows in the room. The calculator uses average dimensions to subtract this area.
- Decide on Coats: Enter ‘2’ for most projects. Use ‘1’ for a touch-up or ‘3’ if you are painting a light color over a very dark one. Explore our color inspiration gallery to see what’s possible.
- Check Paint Coverage: The default of 400 sq ft is typical for quality paints like Sherwin-Williams SuperPaint® or Emerald®. If the can specifies a different coverage, update the ‘Paint Coverage per Gallon’ field.
- Review Your Results: The calculator instantly shows the total gallons needed. Always round up to the nearest whole number to ensure you have enough. The intermediate results help you understand how the total was calculated.
Key Factors That Affect Paint Needs
While this Sherwin-Williams paint calculator provides a precise estimate, several factors can influence actual paint consumption:
- Surface Texture: Rough, porous, or textured surfaces like brick or raw drywall absorb more paint than smooth, primed surfaces. You might need 10-20% more paint for these.
- Paint Quality: Higher-quality paints from product lines like Sherwin-Williams interior paints generally have better hide and coverage, meaning you can often get the job done with fewer coats.
- Color Change: A dramatic color change (e.g., painting white over a dark navy) will almost certainly require a primer and at least two coats of paint, potentially increasing your need.
- Application Method: Using a sprayer can consume more paint than a roller due to overspray. However, rollers with a thick nap will hold more paint and may use more than a short-nap roller.
- Primer Usage: Applying a coat of primer, especially on new drywall or when making a big color change, creates a uniform surface that improves the topcoat’s adhesion and coverage, ultimately saving you paint. Check out our range of high-quality primers.
- Paint Sheen: Glossier sheens tend to have slightly less coverage by volume than flat or matte sheens, as they are formulated with more binders and less pigment.
Frequently Asked Questions (FAQ)
1. How many gallons of paint for one room?
A typical 12’x12′ room with an 8-foot ceiling needs about 1 to 2 gallons for two coats. Our Sherwin-Williams paint calculator gives a more precise answer based on your exact dimensions.
2. Is it better to have leftover paint or run out?
It’s always better to have a little leftover for future touch-ups. We recommend buying about 10% more than your calculated estimate, or at least rounding up to the next full gallon.
3. Does this calculator work for both interior and exterior paint?
Yes. The principle of calculating surface area is the same. Just ensure you use the correct coverage rate from the exterior paint can, as it can differ from interior products.
4. Do I need to subtract for electrical outlets and small vents?
No, it’s not necessary. The area of these small items is negligible and is implicitly covered by the buffer you have when you round up your final paint purchase.
5. How does paint coverage change with different units (imperial vs. metric)?
A gallon of paint covers a specific area regardless of units. One gallon covers about 37 square meters, which is equivalent to about 400 square feet. Our calculator handles the conversion automatically.
6. What if my walls have a heavy texture?
For heavily textured walls (like stucco or “popcorn” ceilings), we suggest reducing the ‘Paint Coverage per Gallon’ value by 15-20% (e.g., enter 320 instead of 400) to account for the increased surface area.
7. Why are two coats of paint recommended?
The first coat acts as a base, while the second coat ensures full, even coverage, true color depth, and maximum durability. One coat often looks patchy or uneven once dry.
8. How do I find the coverage of a specific Sherwin-Williams paint?
The coverage rate (in sq ft per gallon) is always listed on the paint can’s label or in the Technical Data Sheet available online. You can also ask an expert at your local Sherwin-Williams store.
Related Tools and Internal Resources
Planning your project involves more than just calculating paint. Explore our other resources to ensure a perfect finish.
- ColorSnap® Color Matching: Have a specific color in mind from an object or photo? We can match it.
- Inspiration Gallery: Browse through professionally designed rooms to find your perfect color palette.
- Interior Paint and Coatings: Explore our full range of award-winning interior paints, from the durable Emerald® line to the popular SuperPaint®.
- How to Paint a Room Guide: Our step-by-step guide walks you through the entire painting process, from prep to cleanup.
- Primers: Learn which primer is right for your surface to ensure the best possible finish.
- Store Locator: Find a neighborhood Sherwin-Williams store for expert advice and to pick up your supplies.