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 350–400 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
—
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 350–400 sq ft per US gallon (≈9–10 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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