Question 1

How much paint do I need for a 12x12 room?

Accepted Answer

For a standard 12×12 foot room with 8-foot ceilings, one door, and two windows, the paintable wall area is about 333 sq ft. With two coats, you need approximately 6.7 litres (or about 1.9 gallons). A single gallon can covers roughly 350 sq ft per coat, so plan for 2 gallons to be safe.

Question 2

How many square feet does one litre of paint cover?

Accepted Answer

One litre of quality interior paint covers approximately 100 square feet (about 9.3 square metres) per coat on a smooth, primed surface. Coverage varies with paint type — flat finishes cover slightly more area than satin or semi-gloss, and textured or porous walls reduce coverage by 10-20%.

Question 3

How many coats of paint do I need?

Accepted Answer

Most paint jobs need two coats for even, durable coverage. One coat may suffice when painting over the same colour or using a high-quality paint-and-primer-in-one. Going from a dark to a light colour may require three coats. Always apply a primer first on bare drywall, patched areas, or when making dramatic colour changes.

Question 4

Should I subtract door and window area from my paint calculation?

Accepted Answer

Yes — subtracting doors and windows gives a more accurate paint estimate and avoids buying excess. A standard interior door is about 21 sq ft and a standard window about 15 sq ft. For rooms with many openings, skipping this step can overestimate paint by 15-20%.

Question 5

What is the difference between a litre and a gallon of paint?

Accepted Answer

One US gallon equals approximately 3.785 litres. A gallon of paint covers about 350 sq ft per coat, while a litre covers about 100 sq ft. In the US, paint is sold by the gallon; in most other countries, it is sold by the litre. Our calculator shows both units for convenience.

Question 6

How much extra paint should I buy for touch-ups?

Accepted Answer

Buy 10% extra paint beyond your calculated amount. This covers uneven surfaces, touch-ups after furniture moving, and minor wall repairs. Keeping leftover paint from the same batch ensures a perfect colour match for future touch-ups — store sealed cans in a cool, dry place for up to 10 years.

Question 7

Does paint coverage change for textured walls?

Accepted Answer

Yes — textured, rough, or porous walls absorb more paint and reduce coverage by 10-20%. For heavy textures like stucco or popcorn ceilings, reduce expected coverage to about 80 sq ft per litre. Always prime bare or textured surfaces first to improve coverage and adhesion.

Paint Calculator — How Much Paint Do I Need?