Advice On Calculating How Much Paint To Buy

Calculating how much paint you need to buy before you go out and shop for it could save you an awful lot of money not to mention time, if you buy too little and then need to go back for more. Follow my simple formula and work out exactly how much paint you need for the job.

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How many tins of paint have you found rusting away in your garden shed?

If you're anything like the average home owner then there will be one or two (dozen?) lurking somewhere.

Now some of those tins of paint were plain old mistakes, i.e. you bought a colour on the spur of the moment and when you tried it on the wall it just looked wrong.

But I guess a lot of those odd cans of paint could be put down to 'buying too much paint and having it left over'.

This time, to help you avoid both spending too much and saving on using more storage space for storing over purchases, use the handy paint calculator table to help you calculate how much paint to buy.

Here are some tips when deciding on how much paint you need to buy and saving money.

Break up the room into manageable sections, see diagram opposite, and calculate the area of each section. Work in either metres or feet, but not both. Don't forget to subtract the area of window, door or other section that is not being painted.
Embossed, patterned, wood chip and textured wallpaper will have a greater surface area and therefore require more paint to cover it, allow 1/3 rd more.
Fresh or unpainted plaster and old wallpaper can be very thirsty. Paint with a slightly watered down emulsion, use some of that left-over stuff from the shed!
Dark colours painted over light or vice versa will require 2 or possibly 3 top coats of paint.
Use some of the left over paint, that you have lurking in your shed, to undercoat dark colours. This will help cut the cost of painting because you will not be using your expensive 'new' paint to remove the old colour.
If you are painting over a light colour with a dark paint, buy some universal paint 'tint' from good 'Decorating' merchants and tint up some of that left-over paint. Again this will save on using your 'new' paint for the under coat.

Here's how to measure a room area.

Divide your room into easy to identify sections.

In this example there are 6 sections over these two walls.

For each section multiply the height of the section (A) by the width of the section (B) this gives you the area measurement of each section.

Now add all 6 areas together to get the total area of the room.

Don't forget you must use either imperial or metric for all measurements. Never mix the two.

Use the chart below to help you calculate how much emulsion paint you will need to paint a single coat in an internal room. One litre covers approx 14 sq m (150 sq ft).

The room is an average height room of 2.4 mtrs

Room size	Paint for walls	Paint for Ceilings
3 x 3 m	1.3 ltr	0.7 ltr
3 x 4 m	1.6 ltr	0.9 ltr
3 x 4.5 m	1.6 ltr	1.0 ltr
4 x 4 m	1.9 ltr	1.2 ltr
4 x 4.5 m	1.9 ltr	1.3 ltr
4 x 5 m	2.2 ltr	1.4 ltr
4 x 5.5 m	2.2 ltr	1.6 ltr
5 x 5 m	2.2 ltr	1.8 ltr
5 x 5.5 m	2.5 ltr	2.0 ltr
5 x 6 m	2.8 ltr	2.3 ltr

The area a litre of paint will cover for different styles of paint
Coating	Coverage per Ltr
All purpose primer	12 sq m (130 sq ft)
Undercoat	16 sq m (170 sq ft)
Gloss	14 sq m (150 sq ft)
Non-drip gloss	12 sq m (139 sq ft)
Emulsion	14 sq m (150 sq ft)

Useful Resources

Benjamin Moore - This great US website is of interest to anyone who is decorating. There is loads of useful information on how to decorate with paint, how to try out colour schemes and loads of inspirational ideas - www.benjaminmoore.ca/howto/paint

Paint Forum - is another great information resource for anyone wanting to know more about paint and how to use it - www.painterforum.com

The Paint Quality Institute - has websites based in all major countries so there is a British site, a US site etc Great for all things paint and paint quality - www.paintquality.co.uk/ www.paintquality.com

The BBC - offers fantastic free advice on all things home decorating. Check out their home DIY section for loads of ideas and advice on how to do it right www.bbc.co.uk/homes/diy/paintcalculator

The Green Guardian - This site takes a look at the greener side of decorating. Find out what products to use to help care for the environment. Find out how to ethically and dispose of unused paint and other decorating products.www.greenguardian.com

This Old House - A US building show has this great website for any enthusiastic DIYer. Take a look for lots of ideas about caring for your property and doing the job right. www.thisoldhouse.com/toh/knowhow/interiors/article

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There are loads of good ideas on how to 'Use What You've Got' or buy and use second hand furniture and furnishings in The Property Coach 'Home Staging Handbook'.