Question 1

How do I calculate paint for a room?

Accepted Answer

To calculate paint needed: (1) Measure room length, width, and height. (2) Calculate wall area: 2 × (length + width) × height. (3) For ceiling, calculate: length × width. (4) Subtract door areas (1.9m² each) and window areas (1.5m² each). (5) Divide net area by coverage rate (typically 10-12 m²/L) and multiply by number of coats. Add 10% waste factor for safety.

Question 2

How much does one liter of paint cover?

Accepted Answer

One liter of paint typically covers 10-12 m² per coat. The exact coverage depends on paint quality, surface texture, and porosity. Premium paints may cover up to 14 m²/L, while textured surfaces or porous materials may reduce coverage to 8 m²/L. Always check the manufacturer's specifications on the paint can.

Question 3

Do I need to subtract doors and windows?

Accepted Answer

Yes, you should subtract doors and windows from your wall area to get an accurate paint estimate. Standard doors are approximately 1.9 m² (810mm × 2040mm including frame), and typical windows are 1.5 m² (1200mm × 1000mm including frame). Our calculator automatically deducts these based on your door and window counts.

Question 4

How many coats of paint do I need?

Accepted Answer

Most painting projects require 2 coats for optimal coverage and color depth. One coat may be sufficient when painting over the same or similar color. Three or more coats are recommended for dramatic color changes (dark to light or vice versa), new drywall, or when using light colors over dark surfaces.

Question 5

Should I use primer before painting?

Accepted Answer

Use primer for: new drywall or plaster, bare wood surfaces, covering stains or water damage, dramatic color changes, or when switching from oil-based to water-based paint. Primer improves paint adhesion, provides uniform coverage, and reduces the number of finish coats needed. One coat of primer is typically sufficient.

Question 6

What is a reasonable waste factor for paint?

Accepted Answer

A 10% waste factor is standard for painting projects. This accounts for paint absorbed by rollers and brushes, overspray, spillage, and touch-ups. For complex rooms with many corners or textured surfaces, consider 15%. Professional painters often add 10-20% to ensure they have enough paint to complete the job without color matching issues.

Question 7

How do I measure room dimensions accurately?

Accepted Answer

Use a tape measure to measure in millimeters: (1) Measure length along one wall at floor level. (2) Measure width along an adjacent wall. (3) Measure height from floor to ceiling in a corner. For irregular rooms, break them into rectangular sections and calculate each separately. Round up to the nearest 100mm for simplicity.

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