Getting your measurements right before painting saves you money and multiple trips to the paint shop. After 15+ years painting Melbourne homes, I’ve seen too many DIYers buy three extra tins they didn’t need or run out halfway through a wall. Here’s how to measure properly.
What You Need
- Tape measure (5-8 metres)
- Notepad and pencil
- Calculator
- Step ladder for high areas
That’s it. Simple tools, accurate results.
Measuring Walls
Use this basic formula: Width × Height = Square Metres
Measure each wall separately, even if the room looks square. I’ve worked in plenty of Melbourne homes where opposite walls differ by 10-15cm, especially in older properties.
Step-by-step:
- Measure wall width at floor level
- Measure height from floor to ceiling (most Aussie homes are 2.4m, but always check)
- Multiply width by height
- Write it down immediately
- Repeat for each wall
Add all wall areas together for your total.
Doors, Windows and Openings
Should you subtract them? Here’s the professional approach:
- Standard door: 2 square metres
- Average window: 1-2 square metres
For tight budgets, subtract these from your total. For a comfortable buffer that accounts for waste and touch-ups, leave them in. Your choice depends on whether you’d rather have leftovers or risk running short.
Ceilings Are Simple
Length × Width = Ceiling Area
A room that’s 5m × 4m = 20 square metres. Remember, textured ceilings need more paint than smooth ones.
Calculating Paint Quantity
Paint tins list coverage rates, usually 10-14 square metres per litre.
Formula: Total Area ÷ Coverage Rate = Litres Needed
Example: 40 square metres of wall ÷ 12m² per litre = 3.3 litres for one coat.
Don’t Forget Multiple Coats
New plaster or colour changes for interior painting need at least two coats. Dark colours covering light (or vice versa) often need three.
Multiply your single coat calculation by the number of coats required.
Quick Example
Bedroom walls:
- 4 walls totalling 36m²
- Minus door (2m²) and window (1.5m²) = 32.5m²
- Two coats needed
- Paint covers 12m² per litre
Calculation: (32.5 ÷ 12) × 2 = 5.4 litres
Buy a 4-litre and 2-litre tin. Done.
Pro Tips from the Field
Add 10% extra: Professional painters always include a buffer for spills, waste and future touch-ups. Multiply your final number by 1.1.
Measure high areas carefully: If you’re tackling exterior painting, second-storey walls and eaves need accurate measurements. Safety first—use proper equipment.
Write everything down: Don’t trust your memory. I’ve measured the same wall three times because I forgot to note it.
Round up when buying: Half a litre short on Sunday arvo when Bunnings is closing? Not ideal. Always round up.
Check paint coverage rates: They vary significantly between brands. Cheap paint might only cover 8-10m² per litre, while premium covers 13-15m². Sometimes expensive paint works out cheaper because you need less.
Common Mistakes to Avoid
Forgetting second coats is the biggest one. Always multiply by number of coats before heading to the shop.
Don’t assume all rooms have the same ceiling height. Measure each separately, especially in renovated homes or extensions.
Textured walls use 20-30% more paint than smooth surfaces. Factor this in.
When to Call Professionals
Measuring is straightforward for single rooms, but whole-house projects get complex fast. Multiple rooms, different ceiling heights, exterior areas, woodwork—it adds up.
Professional painters provide free quotes that include accurate material calculations. We’ve got the experience to spot issues before they become expensive problems. Whether you need residential painting or commercial work, getting measurements right is where quality jobs start.
Bottom Line
Twenty minutes with a tape measure saves hours of frustration. Measure each wall, calculate coverage, multiply by coats needed, add 10% buffer. Simple formula, professional results.
Need help with a bigger project? Contact us for a free quote. We’ll measure accurately and give you a detailed breakdown of what’s needed.