How much paint do i need?

How much paint do I need for my project?

If you’re asking these questions, you’re not alone. Buy too little paint and you end up back and forth to purchase more. Buy too much and you end up with cans stacked up in the shed (although this could be useful for touch ups!)

If only such thing as a paint calculator existed, eh? Well, you’re in luck, because we’re here to show you just how simple it can be to calculate the paint you need

Step 1: Measure up

First off, you need to grab a tape measure to work out the height and width of the surface you want to paint. Then, multiply the height and width together to get your square metre measurement.

Subtract any windows and doors by using the same calculation method and deducting it from the total.

For Example

Wall 1 Length 4mtrs X Height 2.8mtrs = 11.2sqm

Wall 2 Length 10mtrs X Height 2.8mtrs = 28sqm

Wall 3 Length 4mtrs X Height 2.8mtrs = 11.2sqm (minus door 1mtr X 2mtr) 11.2sqm – 2sqm = 9.2sqm

Wall 4 Length 10mtrs x Height 2.8mtrs = 28sqm (minus window 1.5mtrs x 2mtrs) 28sqm – 3sqm = 25sqm

Add all 4 walls together total = 73.4sqm (1 coat)

Step 2: Calculate your coats

How many coats of paint do I need?

Generally, you will want a minimum of two coats of paint – this is a good rule of thumb for any wall or ceiling you’re painting. You’ll rarely get a seamless finish from just one coat of paint, and even if you do, coverage isn’t the only goal when it comes to painting a room. You also want to prepare your walls for the coming years of wear and tear, cleaning, wiping and sunlight – in short, you want the paint to be durable. This is where two coats of paint really help.

How many coats of paint on a wall?

Let’s dive into specifics now. Based off our rule of thumb, two coats of paint is the absolute minimum you’ll want for your walls. However, the material and previous colour of the wall can both influence this number – for unfinished drywall, for example, you’ll want to add a coat of primer or undercoat paint too. If the wall was previously painted a darker colour than your new paint, you’ll want to add another coat to really make that lighter colour cover up the darker hue beneath.

How many coats of paint on a ceiling?

When it comes to ceilings, you could get away with one coat of paint, especially if just refreshing a white ceiling with a fresh coat. Tikkurila Anti Reflex 2 White Paint is a brilliant option for ceilings. With only 2% sheen it is very forgiving when cutting in around spot lights and works beautifully on ceilings large and small. Although you may get away with one coat when just refreshing your white ceiling, two coats will really give a bright and fresh finish.

How many coats of paint on new plaster?

When it comes to painting over new plaster, you’ll technically want three coats of paint – our two recommended coats plus a mist coat. A ‘Contract matt’ is specially designed for use on new plaster.

So for 2 coats take the Total Sq mtr from Step 1 73.4sqm x 2 (coats) = 146.8sqm

Step 3: Divide by paint coverage

Finally, divide the number by the square metre per litre listed on your paint tin or in the online product information. And there you have it, you’ve worked out the amount of paint you need.

Each type of paint will have a slight;y different coverage rate. look for the coverage rates


Coverage will vary depending on the thickness of the application and number of coats needed, we would suggest going with the lower figure, but hopefully you will get a slightly better rate then this suggest.

Example 10-12sqm per litre (will do a calculation for both)

10sqm per litre – total sqm required 146.8sqm divide by 10sqm = 14.68 litres

12 sqm per litre – total sqm required 1463.8 sqm divide by 12sqm = 12.23 litres

From here you can decide how much paint to buy.

Paint usual comes in 1ltrs, 2.5ltrs, 5ltrs and 10ltrs depending on colour and finish. So at the best coverage rate you would need 12.5ltrs and at worst 15ltrs.

What paint do i need ?

It can be easy to get overwhelmed with the different types of paints available. But by choosing the right features and colours for the right room, you can end up with the perfect finish that lasts longer

Most paints fall into two solvent categories that define their type: water-based or oil-based. Here’s a guide to the difference between the two.


As the name suggests, water-based paint has water as a solvent. You can use water-based paint in almost any application in the home, from exteriors and trim to interior walls and woodwork.

Water-based paints are:

  • Easy to clean with soap and water • Kinder to the environment; typically contain fewer VOC’s
  • Fast-drying


These are also known as solvent-based paints and are usually reserved for areas subject to heavy wear or prone to impact. These include trim, floors, and sometimes cabinets.

Oil-based paints are:

  • Best suited for use on metal and wood
  • Slower to dry, sometimes up to 24hrs. However, it doesn’t show brush strokes as much. This is an advantage when painting trim, woodwork, and cabinetry.

Paint finishes

Choosing the right sheen level can completely transform the look of a room, so it’s important that you understand the impact different types of paint finishes can have on a space. Let’s go over the different finishes

Matt emulsion is a smooth and velvety paint that helps to hide imperfections as it doesn’t reflect light. The finish is the opposite of glossy and looks similar to paper. Matt finishes work well in any style of room but work particularly well if you’re trying to achieve a classic or period look and feel.

Eggshell has less of a sheen than silk or satin and it does look like the surface of an eggshell (the clue is in the name). It sits somewhere between matt and a silk finish and gives a beautiful classic look to woodwork – and can also be used on walls when you want a heritage style look with a tough finish.

Satin and Silk are ‘mid-sheen’ finishes, which means they look like a slightly polished surface and reflect a bit of light. Silk is a finish associated with walls and satin for woodwork. You can wipe clean silk wall finishes easily which makes them very practical, but if you have less-than perfect walls, all the lumps and bumps may show up a bit more. A satin finish on woodwork helps to hide imperfections and gives colour a softer appearance.

Gloss is a shiny finish designed for woodwork and it reflects lots of light – so is perfect for paler colours. You have to have a great surface to make it look its best as it’ll show all the lumps and bumps. But it is hugely practical and adds a lovely contrast to walls that are painted in a matt.

What is primer?

A primer is a special type of paint that is used as a base coat (or undercoat) to help the paint stick to the surface it’s covering. Primers are most used on wood or metal, but sometimes walls need priming as well, especially if you’re painting on bare plaster or brickwork. Primers contain more oil, are generally thinner, and, in most cases, are designed to soak into a surface.

What is an undercoat?

The undercoat is essentially the layer of paint underneath the topcoat, just like a primer. It helps the top layer look smooth and professionally finished. Many products are self-undercoating, saving time and money. An undercoat carries more pigment, and its main roles are to totally cover the previous surface colour and to ‘key’ onto the existing surface, providing a suitable base for the topcoat of paint. We recommend undercoat if you’re going for a dramatic colour change.

If you are still unsure or would just like some further advice or help calculating your needs, please feel free to contact us

Zinsser – Mould & Mildrew

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After priming with stain-blocker Zinsser B-I-N® AQUA, simply apply two coats of Zinsser PermaWhite to prevent mould and mildew. PermaWhite is the ultimate paint for any room with high humidity or poor air circulation.

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