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How to choose the right drill bit for the job

Workshop Legend



Choosing the right drill bit plays a huge role in making your drilling project is a success. It can help you use your power drill efficiently and safely.


However, there are many types of drill bits available, and it can be tricky to work out which one you need for your project.


Here is our guide to selecting and using the right drill bit so you end up with a fantastic result every time. 

Choosing bits based on material


The type of material you are drilling into plays a huge role in selecting the right type of drill bit for your project.


Here are some common materials and the type of bits best suited for them:

Timber (hardwood, softwood, MDF or chipboard)

For these natural and manufactured timbers, we advise using high speed steel bits, or HSS.  HSS bit.jpg


Soft metals (sheet metal, aluminium, copper or brass)

These softer metals can be drilled using a sharp HSS bit.

Hard metals (stainless steel, bronze or cast iron)

These higher hardness level metals are best drilled using a cobalt bit.


These can easily be drilled with HSS bits. However, it is advisable to run your drill at a lower speed. A fast drill can heat up and melt the material, resulting in swarf melting and sticking onto the material you are trying to drill into.

Masonry (brick, roof, wall or floor tiles, blocks, concrete and stone)

A masonry bit should be used for these materials. In most cases, we recommend using a hammer drill on hammer setting to aid the drilling process. Note that if drilling tiles, hammer setting might crack them. For very dense igneous rocks like granite or basalt, you may need to use specialised drill bits.

Hard tiles, porcelain, glass

We recommend using a specialised diamond core bit or glass and tile spade bit for these. These bits must be kept wet while drilling. You can also use a fresh and sharp standard masonry bit. Keep area wet while drilling with diamond bitsKeep area wet while drilling with diamond bits


Blended materials

There may be times where you have to drill through multiple layers of materials. For example when wall framing, you may have to drill through tile and compressed cement sheets. We recommend using a multi-material or construction bit. These are designed for drilling through a range of tile, masonry, timber and metal materials.


Choosing bits based on hole diameter

It is also important to know the hole diameter you require for your project. This determines the type and size of bit you will need.


Here are two common types of holes and the types of bits most suited for them:

A clearance hole

This hole is the correct size for your fastener to snuggly pass through. For example, if you are using M12 bolts, you ideally want a hole slightly larger than the M12 (12mm) bolt to avoid having to hammer it through. A 12.5mm or 13mm bit is ideal.

A pre-drill or pilot hole

This is when you need to drill holes smaller than your fastener. To use our M12 example again, if you were using a large M12 coach-screw, then you would drill a pilot hole of 10mm to 10.5mm.


Choosing bits based on hole depth


In situations where you need to drill through your material, the bit should be at least 10mm to 20mm longer than the material thickness. This allows for the bit to cut a clear hole out the other side.


Ideally, the length of the drill bit should be measured against the length of its fluted section, not including the straight shank section at its base. This helps to avoid the risk of your chuck spinning against and damaging the face side of the material.

If you only need to drill about 30mm into a material, then use a bit that has extra fluted length. It is good practice to drill holes a little deeper than needed, especially in masonry. In these situations, drill swarf can fill the hole and reduce its depth.

Specialised bits

There are a range of bits designed for specific purposes. These include:

Spade and short auger 

These are designed for clearing short holes through timber quickly. Available mostly in larger diameters, they are used for running holes through framing for plumbing and electrical cables. Both bits have a sharp positioning and starter tips with the larger cutting section behind. Spade bitSpade bit


Long augers

These are used when a long hole is needed to be drilled through timber. For example, when you may need to run cables, pipes or cyclone rods through framing, floorboards and bearers or joists.


These bits look more like a router bit than a drill bit. They are designed for creating holes with flat bottoms. For example, when fitting dowels in furniture or concealed hinges in cabinetry.

Brad point 

These bits have a sharp position tip and raised cutting spurs on the outside edge of the flutes. They are designed for clean cutting when making furniture, or other similar projects.


Designed specifically for use with impact drivers, these are designed to withstand percussive force emitting from the drivers.

Hole saws

These are used mainly to drill perfectly round holes. A cylindrical saw blade fits into a mount with a drill bit in the centre. It positions the saw and guides it through.Hole sawHole saw

Step drill 

These bits have tiered cutting stages. They are designed for cutting accurately sized holes through materials such as thin sheet metal, plastic, aluminium and fibreglass.

Counter sinking 

These come in a variety of forms. The basic ones are mainly used to drill wide holes for screws that sit flush with the surface. Others have an integrated pilot drill so that you can both pre-drill and counter sink.

Panel or rivet 

Very short bits designed specifically for use when pre-drilling metal for riveting. Their diameters are matched to rivet sizes. Some are also double ended.

More helpful tips for using tools 


Adam has shared a series of tips for drilling in our Best Advice sectionThe Bunnings Workshop community team has also shared these useful guides as part of our tools series: 


Need more help?


The Bunnings Workshop community is here to assist if you need a hand in choosing the right drill bit for your project. Don't hesitate to hit the Start a discussion button and let us know your needs.


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12 Replies
Kind of a Big Deal

Excellent summary @Adam_W!


Is there any way of looking at a screw and saying - "yes, that's a metal self-tapping screw."


This one.




Edit : Sorry, posted this on the wrong thread - suppose to be the screw thread.

Bunnings Team Member
Bunnings Team Member

Hi @Noyade,


I'm also keen to hear from @Adam_W if there are any clues we should be making use of. Here's my tried-and-true method of selecting. Been using it for years.





Kind of a Big Deal

Hey @MitchellMc 


Did you grind the tip of the self-tapper seen in the middle photo - to make what's seen on far right? 😛


Apologies again for the screw question in a topic on drills - old age. In the end the screw I showed above worked well as a self tapper. Odd head (like mine) which fitted a 7mm socket and a T20. Dunno where it came from...

Bunnings Team Member
Bunnings Team Member

Hi @Noyade


Self-tapping steel screws from my experience always have that very particular end on them. They also have those very high screw threads to latch on to steel. 





Kind of a Big Deal

Hi @EricL 


"Self-tapping steel screws from my experience always have that very particular end on them."


Not that I'm an expert on screws - but I don't think you have to have a ''self-drilling" component at the end before it can be described as self-tapping.

See here...



Bunnings Team Member
Bunnings Team Member

Hi @Noyade


I've always had to use a centre punch to mark the steel to prevent the tip from floating around. I suppose it depends on the thickness of the steel you are drilling into.




Kind of a Big Deal

Eric - I even drill a pilot hole for the "Self-Drilling" variety. What can I say - I'm a wuss. 😔

Bunnings Team Member
Bunnings Team Member

Hi @Noyade


I've done similar steps in specific projects in the past, some builds sometimes require that a pilot hole be drilled for perfect fitting. 




Kind of a Big Deal

How we drilled into brick/masonry in 1947...



Just Starting Out


This information will definitely come in handy for future projects!

My issue is .. amongst the many drill bits

(I inherited) how can I identify which drill bit is what! Can you please provide a photo of which bit is the masonry drill bit !  I would love to attach pot plant brackets, shelving, art mirrors etc the the bricks of my home!

not game to drill  into it without advice!

Thank you GEM 💎 

Bunnings Team Member
Bunnings Team Member

Hello @GEMs


Welcome to the Bunnings Workshop community. It's brilliant to have you join us, and thank you for sharing your question about drill bits.


One easy way to identify if you have a masonry drill bit in your hand is its drill bit head. A masonry bit will have a slightly wider head than the rest of its body. Whereas a regular drill bit will be uniform in size from the top to the bottom. Both drill bits will have a tapered head but the timber or steel drill will often have a very sharp edge on its tip.


I've placed some images below to give you an idea of what these drill bits look like. Please have a look and if you have any questions concerning them, please don't hesitate to post your query.






Becoming a Leader

Don't know how long you've been in the business @Adam_W, but your knowledge bank is phenominal!  Thank you for your explanations - both readable and immensely helpful! 🏆

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