Screwdrivers. They seem simple enough, right? They are basically just a handle and a metal tip. That sounds good until you're staring down at a jumble of screws with various cryptic markings and slots. I know that's how I felt when I started looking. That's why I have created this to help give you the knowledge to conquer any screw, understand the confusing world of head types and sizes, and build the perfect screwdriver set for your household needs.

Just before we begin, you will see a term called "cam out, or camming out." This refers to the screwdriver slipping out of the screw head when force is applied.

Screwdriver Head Types: A Visual Guide

It's easier to forget about screwdrivers initially. I think it's easier to see what types of screws are used in the UK. By understanding those, then you can pick the right type of screwdriver for the screw. You can buy individual screwdrivers, sets of screwdrivers and screwdriving bits, that can be used with a drill/driver or an impact driver.

Slotted Heads

slotted flathead screw

Flathead screws, are also known as slotted screws. They have a flat, wide head with a single slot running down the centre.

They are commonly used in woodworking, furniture assembly, and other applications where a flush or low-profile appearance is desired.

You will find these in older furniture and appliances.

The disadvantages of these is that the screwdriver can easily slip out as there is not much contact between the screw and the head of the screwdriver.

Phillips Heads

philips screw head from various angles

This has a ubiquitous cross-shaped head, that is easy to recognise and is used in a wide range of modern appliances, from electronics to toys.

They offer a more superior grip and torque compared to slotted screws, making them ideal for a wide range of tasks, from assembling electronics to tightening furniture joints.

They are widely available, their cruciform head makes them self-centreing, which means they can be fastened with one hand.

The cross-shaped indentations are tapered, which helps the screwdriver maintain a good grip on the screw.

Torx Heads

torx head screws displayed at different angles

These have a 6 pointed star-shaped head and some people call these star heads. They are best used for superior grip and torque. These will be used in high-end furniture and specialised equipment.

You will find these used a lot in vehicles, motorcycles, bicycles, computer systems, hard disk drives and consumer electronics.

They are becoming very popular in the UK. They are much better at reducing cam out when compared to flat head or Phillips screws.

Robertson Heads

robertson screws

As you can see, Robertson screws have a distinctive square head with a recessed socket in the center. This design prevents cam-out (slipping) during use, making them ideal for high-torque applications, especially in construction and woodworking.

They come in various sizes, typically designated by numbers (e.g., #2, #3) or letters (e.g., SQ2, SQ3).
They offer superior grip compared to Phillips or slotted screws, making them easier to turn and less prone to damage.
They're commonly used in Canada and gaining popularity in other regions, particularly for furniture assembly, electrical installations and heavy-duty projects.

Pozidriv Heads

pozidriv decking screw

These are similar to Phillips but they have additional diagonal ribs for extra grip and reduced cam-out. They are found a lot in European-made furniture and appliances.

They are also used a lot for decking boards.

These allow you to use more torque without camming out when compared to Phillips.

Phillips screwdrivers will fit Pozidriv screws, and can turn them. They are liable to slippage, and can damage the screw.

Pozidriv screwdrivers, on the other hand, do not fit Phillips heads. If you try, it won't work and you’ll probably damage your screw.

Understanding Screwdriver Sizes

Now that you have seen the different head types, it's time to explain screwdriver sizes. These dimensions are typically etched onto the metal shaft (shank) using either numbers or letters.

Durable 6pc Screwdriver Set – Chrome Vanadium Steel with Magnetic Tips – Includes 3X Flat-Head Sizes: 3x75mm/5x100mm/6x100mm and 3X Phillips-Head: PH0x75mm/PH1x100mm/PH2x100mm

Typical 6pc Screwdriver Set with 3 X Flat-Head Sizes; 3x75mm/5x100mm/6x100mm and 3 X Phillips-Head; PH0x75mm/PH1x100mm/PH2x100mm

Number Systems

The numeric system is the most common for screwdrivers like slotted and Phillips. Here's a general rule of thumb: higher numbers equal larger sizes. Think of it like climbing a ladder – the higher you go, the bigger the platform (screw head).

Size Number

Relative Size

Item 3



Perfect for intricate electronics or miniature furniture repairs. Imagine dealing with a screw smaller than your little fingernail.



Suitable for small electronics components, delicate toys, or precise tasks. Think watch repair or intricate hobby work.



The most common size for everyday household tasks like furniture assembly, light switch covers, or appliance covers. A jack-of-all-trades for most DIY projects.



Handles bigger jobs like assembling heavy furniture, tightening sturdy door handles, or working on larger appliances. Consider it the muscleman of the screwdriver family.

#4 - #12

Increasingly larger

As you climb the numbers, you enter the realm of heavy-duty applications like construction work, machinery maintenance, or industrial tasks. These are the giants of the screwdriver world.

Letter Systems

Torx and Robertson screwdrivers often use a letter system, where alphabetical progression signifies increasing size. Each letter leads to a bigger size. (screw head).

Size Number

Relative Size

Item 3



Ideal for precision electronics work, like opening smartphones or repairing small gadgets. Think micro-surgery for your tech equipment.



Handles small electronics components, like securing laptop parts or tightening delicate mechanisms. Perfect for intricate tinkering.



The go-to for most household electronics and appliances, like TVs, game consoles, or kitchen gadgets. Your average electronics repair sidekick.

T20 - T40

Increasingly larger

Venture into bigger territory with furniture assembly, heavy appliances, or outdoor equipment. These are the workhorses of the toolkit.

By understanding the numbering and lettering systems, you can better choose the right screwdriver size for any task at hand. Remember, it's always better to have a slightly larger screwdriver than one that's too small to avoid damaging the screw head or struggling with poor grip.

Building Up Your Household Toolkit

Rolson 28882 58 pc Screwdriver Set

Rolson 58 piece screwdriver set

Swanlake torx set

SWANLAKE 13-Piece Magnetic Torx Screwdrivers Set

Amazon Basics 51-Piece Precision Screwdriver Bit Set

Amazon Basics 51-Piece Precision Screwdriver Bit Set



Check Amazon UK


One slotted screwdriver in a medium size (#4 or #5). Two Phillips screwdrivers, one small (#0 or #1) and one medium (#2 or #3)


A Torx screwdriver set (T5-T25) covers most common electronics and furniture needs. The average price for these is around £10-15
A Robertson screwdriver (Square Drive #2) comes in handy for Ikea furniture and some appliances. The average price for these is around £10


A precision screwdriver set for tiny electronics repairs. The average price for these is around £10.
A ratcheting screwdriver for added speed and comfort on repetitive tasks. The average price for these is around £8-10.


If you own a drill/driver then buying a set of bits is the best and most affordable option. A good set costs around £10

My Final Thoughts

I hope this article has brought more clarity to the various screwdriver types and the various sizes available. There are lots of options available on the UK market, so you will have plenty of choice. My best advice is to avoid the pound shop offers as buying those is a waste of your  money. They are cheap because they are made of cheap metal and the ends of screwdrivers and bits just start to break when using them.

Always invest in good quality brands and they will last you a lifetime.

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  1. Hi
    Thanks for the interesting info. A fellow railway modeller has enquired on our forum what is meant by a No. 4 miniature screwdriver. It seems that, in the instructions, one is required to score some planking on a model kit he is building.

    I've scoured the internet and can't find a numbering system for miniature (or watchmakers') screwdrivers. Have you any ideas?

    1. Thanks Richard. Over the years I have used a lot of screwdrivers. I have never seen numbered ones though. Any I have used are just shown by size. I haven’t done model railways either so genuinely can’t offer any useful advice. I hope you can find out somewhere else and apologies for not being able to help.

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