How do I find my wall area?

Multiply each wall's width by its height and add them together, then subtract large door and window areas if you want a more precise number — for a rough estimate, most people skip subtracting openings since it just adds a small safety margin.

Why does coverage per gallon vary?

It depends on the paint formula, the wall's texture and porosity, and the application method — check the specific number printed on your can rather than assuming a universal figure.

How many coats should I plan for?

Two coats is standard for most repaints, though a dramatic color change (like going from dark to light) or a bare/porous surface may need a third coat or a dedicated primer coat first.

Should I buy the exact amount calculated, or a bit extra?

It's generally wise to round up slightly beyond the exact calculated amount for touch-ups later and to account for minor spills or an uneven surface soaking up more paint than expected.

Does ceiling paint need a separate calculation?

Yes — ceilings are typically a different paint type with their own coverage rate, so calculate ceiling area and paint needs separately from your wall calculation.

Construction & Home Improvement Cluster

Paint Calculator

Calculate how many gallons of paint you need.

TL;DR: Paint Calculator is a free, browser-based tool that lets you calculate how many gallons of paint you need.

Wall area (sq ft)

Number of coats

Coverage per gallon (sq ft)

Understanding the Paint Calculator

The Paint Calculator estimates material quantities, square footage, and project costs for home improvement, carpentry, masonry, and architectural builds.

How It Works

Measure the dimensions (length, width, height, or thickness) of your project area.
Enter dimensions into the estimator with unit selection (feet, inches, meters).
View the total required material volume, square footage, and standard retail package counts.
Add a 10%–15% waste factor before placing material orders at building suppliers.

Mathematical Formula & Methodology

Here is the standard mathematical equation used to calculate this result accurately:

\text{Gallons Needed} = \frac{\text{Total Wall Area} - \text{Windows/Doors}}{\text{Coverage per Gallon (350 sq ft)}} \times \text{Coats}

Formula Variables Explained:
Estimates paint gallons required for interior rooms and exterior walls accounting for two-coat coverage.

Step-by-Step Worked Example

A 12x14 ft room with 8 ft ceilings (416 sq ft wall area) minus 40 sq ft for door and window = 376 sq ft. For 2 coats (752 sq ft total): Need $752 / 350 = 2.15 \implies 3\text{ Gallons}$ .

How to Get the Best Results

The 10% Waste Factor Rule: Always add 10% to 15% extra material to cover corner cuts, edge trimming, breakage, and irregular boundaries.
Measure Twice: Take multiple measurements across diagonal corners to account for non-square walls and uneven excavation grades.
Supplier Package Yields: Check exact coverage per box or bag with your local building materials supplier.

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100% Client-Side Privacy Guarantee

All processing runs locally inside your browser using JavaScript and HTML5 APIs. Your data, files, and inputs are never uploaded to any remote server. Complete privacy by design.

Frequently Asked Questions

: Multiply each wall's width by its height and add them together, then subtract large door and window areas if you want a more precise number — for a rough estimate, most people skip subtracting openings since it just adds a small safety margin.
: It depends on the paint formula, the wall's texture and porosity, and the application method — check the specific number printed on your can rather than assuming a universal figure.
: Two coats is standard for most repaints, though a dramatic color change (like going from dark to light) or a bare/porous surface may need a third coat or a dedicated primer coat first.
: It's generally wise to round up slightly beyond the exact calculated amount for touch-ups later and to account for minor spills or an uneven surface soaking up more paint than expected.
: Yes — ceilings are typically a different paint type with their own coverage rate, so calculate ceiling area and paint needs separately from your wall calculation.

Cite This Tool

Referencing this tool in a paper, article, or bibliography? Copy a ready-made citation below.

NexLove.org. (2026). Paint Calculator [Software]. https://nexlove.org/tools/paint-calculator.html

“Paint Calculator.” NexLove.org, 2026, nexlove.org/tools/paint-calculator.html.

NexLove.org (2026) Paint Calculator. Available at: https://nexlove.org/tools/paint-calculator.html (Accessed: 2026).

@misc{nexlove_paint_calculator,
  title = {Paint Calculator},
  author = {{NexLove.org}},
  year = {2026},
  url = {https://nexlove.org/tools/paint-calculator.html}
}

Embed This Tool

Add the live Paint Calculator tool to your own website with this snippet — it loads the real, working tool in an iframe, not a static screenshot.

<iframe src="https://nexlove.org/embed/paint-calculator.html" width="100%" height="600" style="border:1px solid #e2e8f0;border-radius:12px" title="Paint Calculator — NexLove.org" loading="lazy"></iframe>

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