DIY Maths


DIY Maths

In this section we shall review the uses of numeracy and maths skills in home improvements and crafts.


We touched on the logistical skills required to move and arrange furniture in the Maths in the Living Room section.

But what about the designing, building and installation of furniture?

Even designing something as simple as a shelf, requires measuring skills and an understanding of trigonometry and mechanics.

Mechanics? Trigonometry?

Mechanics is the area of maths that deal with force and motion. In the case of a wall-mounted shelf, the design needs to be able to support weight. This will require suitable brackets to prevent it from falling when you apply force (in this case weight).

Trigonometry is the maths of the sides and angles that form triangles.

How can triangles help with shelf designing?

All shapes can be broken down into triangles to assist with determining angles.

If you are designing a set of shelves (like a bookcase), there are a number of different joint designs depending on the material being used. Calculating the angles to ensure the strongest joints meet without gaps is very important.

Two lego builders with allen keys and a set of assembly instructions

Assembly instructions are often written/drawn and require measuring, spatial awareness, mechanics, and logistical skills.

Regarding mechanics, you would need to ensure you have used the correct length and thickness of screws/nails. Too small in either dimension and the furniture will not be strong enough. Too large and it could damage the material and weaken the joining area. This form of maths is also used to judge the order and positioning of the assembly stages.

The same knowledge of mechanics assists in selecting the correct fixings for attaching furniture to walls.


Whether you are painting or wallpapering, you will need to use measurement and area calculations.

Both tins of paint and rolls of wallpaper list coverage in square metres. You want to make sure you have the correct amount before you start, or you could have issues getting an exact colour match from a second batch (due to slight differences in manufacturing).

A step ladder with a paintbrush and tin lid in front of a freshly painted wall

I could just pay for a decorator...

Yes, you could. However, most decorators ask that you buy the paint and wallpaper beforehand, so you'd still need to do these calculations. If they are willing to buy the materials for you, this knowledge will still make sure you are not being over-charged.

Surely, they could just tell you how much paint/wallpaper they need?

Unfortunately, paint and wallpaper come in different makes, types and amounts. Paints come in a variety of types which require different numbers of coats and possibly needing a different paint for an undercoat. Also, the colour itself can make a difference to the amount needed.


When it comes to buying and fitting flooring you also need to be able to take measurements and calculate areas.

Rooms, halls, and stairs come in different shapes as well as sizes. This means the area calculations can become trickier.

When buying carpets/lino you want to avoid too much wastage, if nothing else, this will save money. This means using shapes, spatial awareness, and trigonometry to get the most out of it.

Carpet also has a pile value to consider - this is a measurement of both length and number of thread loops.

A close-up of the fibres in a carpet


Anything that requires fitting or installing in a house requires the ability to measure.

If you want a new dishwasher/oven/fridge/freezer to go under a worktop, you need to make sure it will fit.

Understanding capacities can help choose the right appliances for you. When it comes to fridge and freezer space, a food shop involves estimation skills for how much will fit when you get home.

Then there are smaller electrical appliances - such as lamps, alarm clocks, hoovers, and printers. On occasion you may need to change a fuse inside a plug, or the plug itself. This requires some numeracy skills from physics in identifying the right fuse to safely continue operating an appliance.

That's easy! The fuse has the values written on it.

Unfortunately, when a fuse blows, the paper label with this information can be burned to the point at which it can no longer be read.

Festive Decorations

Decorating the house for a special occasion can be great fun. It is also another example of the use of mathematical skills without realising.

How can hanging tinsel involve maths?

First, where do you hang it? This requires spatial awareness and estimation for where it will both fit and have maximum affect.

Then, if it's being hung on a wall, there is the decision regarding how to hang it. This involves mechanics to work out where the best attachment points are. It also requires recognition of symmetry to make sure the tinsel hangs evenly.

If it is instead being hung on a tree, what length and thickness of tinsel is too little or too much?

The same underlying numeracy skills apply for fairy lights, baubles, window decorations, Jack-O-Lanterns, and more.

A cat batting at baubles hanging from a tree

If you have young children or pets in the house, you may also need to consider the height of more fragile decorations.

Arts and Crafts

We reviewed the numeracy and mathematical principles behind art in the Maths in the Living Room section.

These also apply to crafts along with some of the skills included above - depending on the craft project.

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