Surface Area (sq ft) Enter the total area to be painted in square feet (e.g., 400)

Number of Coats (count) Enter how many layers of paint you will apply (e.g., 2)

Paint Coverage Rate (sq ft per gallon) Check the paint can label for coverage (typically 300-400 sq ft per gallon)

Waste Factor (%) (optional) Extra paint for spills, touch-ups, and surface texture (0-50%)

Quick Examples:

Single Room Interior Exterior Wall Repaint

Calculate Clear

This calculator is for informational purposes only. Verify results with appropriate professionals for important decisions. Paint coverage may vary based on surface texture, application method, and product specifications.

Use this free online Paint Calculator to calculate your total paint required in gallons. Simply enter your surface area, number of coats, and paint coverage rate to instantly get results in gallons. The estimate includes an optional waste factor to help ensure you purchase enough paint for your project.

How Total Paint Required Is Calculated

The paint calculator uses a standard coverage formula that accounts for the surface area, number of paint layers, and how much area one gallon of paint can cover. First, the calculator multiplies your surface area by the number of coats to find the total coverage needed. Then it divides by the paint coverage rate to get the base gallons. Finally, it adds a waste factor to account for spills, touch-ups, and surface absorption.

The result is rounded up to ensure you have enough paint. Always check the paint can label for the manufacturer's coverage rate, as this varies by product and finish type.

What Your Paint Calculator Result Means

Your result shows the estimated gallons of paint needed to complete your project. This number helps you plan your purchase so you can buy the right amount without running short or having too much leftover. Paint is sold in standard container sizes, so you may need to round up to the nearest quart, gallon, or five-gallon bucket.

For example, if your calculation shows 2.52 gallons, you would need to purchase 3 gallons to complete the job. A small room might require 1-2 gallons, while a full exterior could need 10-20 gallons or more depending on the size.

These estimates assume two coats and include a standard waste factor. Actual coverage may vary based on surface condition and application method.

Accuracy, Limitations & Common Mistakes of the Paint Calculator

How Accurate Is the Paint Calculator?

The calculator provides a reliable estimate based on standard coverage rates published by paint manufacturers. Most paint cans list coverage between 300-400 square feet per gallon on smooth surfaces. Actual coverage may be lower on rough or textured surfaces, unpainted drywall, or surfaces that require primer. The waste factor helps account for these variables.

Limitations of the Paint Calculator

This calculator does not account for surface texture, which can reduce coverage by 10-25% on stucco, brick, or rough wood. It also assumes consistent application and does not calculate primer requirements. Dark colors painting over light surfaces may need fewer coats, while light colors over dark surfaces may need additional coats. The tool also does not calculate trim, ceiling, or accent wall paint separately.

Common Mistakes to Avoid

• Measuring only wall height times width: Subtract doors, windows, and built-in cabinets from your total surface area for a more accurate estimate.
• Ignoring surface texture: Rough surfaces like stucco or brick absorb more paint. Consider using a higher waste factor or consulting the paint manufacturer for textured surface coverage.
• Forgetting primer: If painting over a dark color or raw drywall, primer may be needed. Calculate primer separately using the same formula.
• Not buying enough: Always round up and consider buying an extra quart for touch-ups. Paint colors can vary slightly between batches.

Frequently Asked Questions

Who is this Paint Calculator for?

This calculator is for homeowners planning DIY painting projects, professional painters estimating paint quantities, and contractors preparing bids. It works for interior walls, exterior surfaces, ceilings, and most standard painting applications.

How do I find my surface area?

Measure the length and height of each wall in feet, then multiply to get square feet. Add all walls together and subtract the area of doors and windows. For a 10 ft by 12 ft room with 8 ft ceilings, each wall is 80-96 sq ft, totaling about 352 sq ft for four walls.

What if I'm painting a ceiling?

Calculate the ceiling separately by measuring the floor area (length times width). Enter this as your surface area in the calculator. Ceilings often require less paint due to their smooth texture, but the calculator provides a safe estimate.

Should I include a waste factor?

A waste factor of 10-15% is recommended for most projects. This accounts for paint left in the can, spills, touch-ups, and surface absorption. For rough surfaces or first-time painters, consider using 15-20%.

Is the Paint Calculator free to use?

Yes, this calculator is completely free with no sign-up required. It works on any device with a web browser.