How Much Paint Do I Need?
Enter your room's measurements and this calculator estimates the gallons (or litres) of paint to buy, with standard door & window deductions, multiple coats and an optional cost estimate. Everything runs right in your browser. No data leaves this page.
Your Room
~21 sq ft deducted each
~15 sq ft deducted each
Use 2 coats when going from a dark colour to a light one, a common issue covered in our paint-colour guides.
Most cans list 350 to 400 sq ft / gallon. Adjust to match your product label.
Leave blank to skip cost. We never invent pricing. Use the figure on your own paint.
Your Estimate
Buy about
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enter room size
Estimated paint cost
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- Wall area-
- Ceiling area-
- Door / window deductions-
- Paintable area (1 coat)-
- Total area (all coats)-
How the numbers work
This calculator is pure arithmetic. No market data, no guesswork about your specific paint. Here is exactly what it does and the everyday reference values it uses:
- Wall area = 2 × (length + width) × wall height. Add the ceiling (length × width) if you tick the box.
- Openings. It subtracts a standard rule-of-thumb of ~21 sq ft per door and ~15 sq ft per window (≈1.95 m² and ≈1.4 m²), the widely used allowances for a standard interior door and an average window.
- Coats. The paintable area is multiplied by the number of coats. Two coats is normal, and a dark-to-light change almost always needs two. See our Winnipeg paint-colour guide.
- Coverage. It divides by your coverage rate. The default 350 to 400 sq ft per US gallon (≈9 to 10 m² per litre) is the range printed on most paint cans; change it to match your product's label.
- Containers. The result is rounded up to whole gallons/litres, because you buy paint by the can.
- Primer & touch-ups. If you flag bare drywall or a dramatic colour change, it recommends a coat of primer. Either way, buying ~10% extra for touch-ups is standard practice.
Estimates only. Actual coverage varies with surface texture, colour and application method. Always check the coverage figure on the can you buy.
Pick the right colour, too
Once you know how much you need, our paint-colour guides help you choose a shade that works in Prairie light.
Painting as part of a bigger refresh?
Georgia Home Design helps Winnipeg homeowners choose colours, stage rooms and pull a whole space together. Let's talk about your project.
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