Paint Calculator – How Much Paint Do You Need to Cover a Room?
Take the guesswork out of painting with our paint coverage calculator. Enter your room dimensions and number of coats to find out exactly how much paint to buy.
Enter room dimensions
Input the length, width, and height of your room in meters. These measurements determine the total wall surface area.
Subtract doors and windows
Enter the total area of doors and windows in square meters. This excludes non-paintable surfaces from the calculation.
Set coats and coverage rate
Specify the number of coats (usually 2) and the paint coverage rate in square meters per liter. Click Calculate to see results.
| Paint Type | Coverage (m²/L) | Coverage (sq ft/gal) | Best For |
|---|---|---|---|
| Flat/Matte | 10-12 | 350-400 | Ceilings, low-traffic areas |
| Eggshell | 10-12 | 350-400 | Living rooms, bedrooms |
| Satin | 8-10 | 300-350 | Hallways, family rooms |
| Semi-Gloss | 8-10 | 300-350 | Kitchens, bathrooms, trim |
| High-Gloss | 7-8 | 250-300 | Doors, cabinets, furniture |
The Basic Formula
Paint coverage starts with wall area: multiply the perimeter by the height. For a rectangular room, perimeter equals 2 times (length + width). Then subtract areas that won't be painted — doors, windows, and large openings. Multiply by the number of coats to get total area to cover.
Coverage Rate Explained
Coverage rate tells you how much area one liter of paint covers. Standard interior paints cover about 10 square meters per liter (or 350-400 square feet per gallon). Premium paints often cover more area, while budget paints may cover less. Always check the manufacturer's label for the specific coverage rate.
Why Surface Type Matters
Unpainted drywall soaks up more paint than previously painted walls. Textured surfaces like orange peel or knockdown need 10-20% more paint than smooth walls. Dark colors covering light walls need fewer coats than light colors covering dark walls.
Add 10% Buffer
Always buy slightly more than calculated. You'll need touch-ups eventually, and paint batches can vary in color.
Measure Large Openings
Standard doors are about 2 m² and windows about 1 m². Large picture windows or French doors remove significant area — measure them individually.
Consider Primer
New drywall, stains, or dramatic color changes need primer first. Primer covers 8-10 m²/L and costs less than finish paint.
Don't Forget the Ceiling
Ceilings need separate calculation. Multiply length times width. Ceiling paint is typically flat and covers about 10-12 m²/L.
How much paint do I need for a 4x5 meter room?
A 4x5 meter room with 2.7 meter ceilings has about 48.6 m² of wall area. Subtract one door (2 m²) and one window (1.5 m²) for 45.1 m² paintable area. For two coats at 10 m²/L coverage, you need about 9 liters or 2.4 gallons of paint.
Is one coat of paint ever enough?
One coat works when repainting the same color or very similar shades. For color changes, especially dark to light or vice versa, plan on two coats minimum. The first coat seals and provides base coverage; the second gives uniform color and sheen.
Does expensive paint cover better?
Generally yes. Premium paints have higher pigment concentrations and better binders, giving better coverage and durability. A $60/gallon paint covering 400 sq ft/gal often costs less overall than a $30/gallon paint covering 250 sq ft/gal.
How do I calculate paint for multiple rooms?
Calculate each room separately, then add the totals. If using the same color throughout, you can buy in larger quantities for discounts. Keep different colors separate in your calculations.
What's the difference between liters and gallons for paint?
One gallon equals about 3.785 liters. In countries using the metric system, paint comes in 1L, 2.5L, 5L, and 10L containers. In the US, common sizes are quarts (0.95L), gallons (3.78L), and 5-gallon buckets (19L).
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