Paint Walls Calculator

How to use the paint calculator:

Step 1: Measure your room

Walk around the room with a tape measure and measure each wall. Add all wall lengths together to get the perimeter (also called room circumference).

Example: A rectangular room that is 4 meters × 5 meters has walls of 4m, 5m, 4m, and 5m. Add them up: 4 + 5 + 4 + 5 = 18 meters perimeter.

Step 2: Measure wall height

Measure from the floor to the ceiling at the tallest point. Most standard rooms are between 2.4 to 2.7 meters high. If your ceiling is uneven or sloped, always use the tallest measurement to avoid running short on paint.

Step 3: Measure doors and windows

Measure the width and height of each door and window opening. The calculator subtracts these areas from your total wall area so you don't buy unnecessary paint.

• Standard door: ~0.9m wide × 2.1m high
• Standard window: ~1.2m wide × 1.2m high

Step 4: Find paint coverage on the can

Check your paint can for "coverage per litre" or "spreading rate". This tells you how many square meters one litre covers with one coat. Typical coverage is 8-12 m²/L depending on paint quality and wall texture. Rough walls need more paint than smooth walls.

Step 5: Choose number of coats

Most painting projects need 2 coats for even coverage and good color. Dark colors over light walls might need 3 coats. Light colors over light walls might only need 1 coat if the existing paint is in good condition.

Step 6: Calculate and get your shopping list

Click "Calculate" and we'll show you exactly how much paint you need. We recommend the best combination of bucket sizes (1L, 3L, 5L, 10L) to minimize waste and cost. You can print the results as a PDF or share the link to save your project.

Pro tip: Always add 5-10% extra paint for touch-ups and mistakes. Keep leftover paint labeled with the room name and date for future repairs.