I get a lot of questions about spanners and wrenches asked by readers of my website. As a result of that interest, I have written this article to explain the various types of spanners, and more importantly, what they are used for. I also want to explain the difference between spanners and wrenches.

In the UK, the words spanners and wrenches are often used interchangeably. They are in fact two different things and used for different purposes. In the USA, they refer to them as wrenches and that does cause confusion. By the time you finish reading this, you will know just about anything you need to know.

What is a Spanner?

A spanner is a tool used to used for turning nuts and bolts to fasten or loosen them. They come in various sizes to suit the many types and sizes of nuts and bolts.

Metric vs Imperial Sizes

Spanners in the UK are sold in both metric sizes and imperial sizes.

  • Metric spanner sizes are measured in millimeters (mm). These are used in countries that follow the metric system for tools and measurements. For example, you will find metric spanners in sizes like 6mm, 8mm, 10mm, 12mm, and so on. Mainly sold in the UK & Europe. These are by far the most popular sizes.
  • Imperial spanner sizes are measured in fractions of an inch and are more prevalent in countries that traditionally use the imperial system. You will find sizes such as 1/4 inch, 3/8 inch, 1/2 inch, etc., which correspond to the sizes of nuts and bolts in the imperial measurement system. These may be required for older machinery or equipment, vintage vehicles, certain types of furniture, or bespoke equipment that uses imperial measurements.

The vast majority of UK buyers will need to buy metric spanners. Those suit modern vehicles, bicycles, household appliances, plumbing etc.

Spanner Types and Sizes in the UK

There are actually 10 different types of spanners. I have shown a list below, and then explained each type, along with a picture so as you can quickly and easily see the difference. You can buy these as a single spanner, but they are mainly sold in sets of different sizes.

  1. Open-ended spanners
  2. Ring spanners
  3. Offset ring spanners
  4. Combination spanners (Combi spanners)
  5. Flare Nut Spanners
  6. Socket spanners
  7. Ratchet spanners
  8. Adjustable Spanners
  9. Box Spanners
  10. Torque Wrenches

The table below compares each type, what sizes are available, and what they are best used for. Underneath the table I go into more detail of each with images to make recognition easier.

Spanner Type

Typical Sizes (UK)

Item 3

Open-ended Spanners

6mm - 32mm (individual sizes or sets)

Simple and versatile, good for quick jobs and limited access.

Ring Spanners

6mm - 32mm (individual sizes or sets)

Secure grip, good for high torque and precision tightening.

Offset Ring Spanners

6mm - 22mm (individual sizes or sets)

Access nuts in tight spaces where straight spanners won't fit.

Combination Spanners (Combi Spanners)

6mm - 32mm (individual sizes or sets)

2-in-1 functionality, open end for quick access, ring end for secure grip

Flare Nut Spanners

6mm - 24mm (individual sizes or sets)

Protects and grips rounded edges of flared nuts in plumbing and gas lines

Socket Spanners

6mm - 32mm (individual sockets or sets with ratchet handles)

Interchangeable sockets offer versatility for various nut shapes and sizes.

Ratchet Spanners

6mm - 32mm (individual sizes or sets)

Fast and efficient tightening/loosening with minimal handle movement.

Adjustable Spanners

6mm - 24mm (single size with adjustable jaw)

Adapts to various nut sizes, eliminates need for multiple spanners.

Box Spanners

8mm - 32mm (individual sizes or sets)

High grip and leverage for heavy-duty tasks and large nuts.

Torque Wrenches

4Nm - 210Nm (individual or sets with preset torque values)

Ensures precise torque application, prevents overtightening and damage.

1. Open-ended Spanners

ExcInter Open Ended Spanner

These take their name as the ends of the spanner are open. (Not closed in) They have two open jaws, usually slightly different in size (one 2mm smaller than the other). That simply means the spanner will be able to turn 2 different sized nuts and bolts. The jaws fit around the head of a nut or bolt, allowing you to grip it from two sides.
They come in various sizes, typically ranging from 6mm to 32mm in the UK market, available as individual spanners or in sets.

Main Uses

  • Open-ended spanners are ideal for quick jobs and situations where limited access is an issue.
  • Their simple design makes them easy to use and maneuver in tight spaces.
  • They're perfect for tasks like tightening furniture bolts, loosening drain plugs, or assembling basic DIY projects.

Benefits

  • Open-ended spanners are relatively inexpensive and easy to find in any hardware store in the UK.
  • They work with a wide range of nut and bolt sizes and shapes.
  • The open design allows for fast access and turning without removing the spanner completely.

Pros:

  • The open-ended design allows them to fit onto nuts and bolts in tight spaces or areas where a socket or adjustable spanner might not have enough clearance to be used effectively.
  • Quicker to apply to a fastener compared to a socket wrench, especially in situations where there's little room to maneuver a ratcheting wrench.
  • When used correctly and with the appropriate size, open-ended spanners are less likely to round off the corners of nuts and bolts compared to adjustable spanners. 
  • Open-ended spanners are available in various sizes, allowing users to have a range of tools to fit different nuts and bolts.

Cons:

  • Open-ended spanners grip the fastener on two sides, which can lead to less contact area compared to a socket wrench.
  • They don't provide as much torque as a socket wrench or a closed-end spanner, which could make it difficult to loosen stubborn or tightly fastened nuts and bolts.
  • There are two specific sizes at their ends, requiring the right size for each fastener. This means you may need multiple spanners to cover a wide range of fastener sizes. 
  • If the spanner is not correctly positioned on the nut or bolt, there's a risk of slipping or stripping the fastener, which could damage both the tool and the fastening element.

2. Ring Spanners

DURATECH Offset Double Ring Spanner

These take their name as the ends of the spanner are closed in a ring shape. That allows them to fit snugly around the entire nut or bolt head. This ring comes in various sizes, typically matching the open-ended spanner range (6mm to 32mm in the UK) and available individually or in sets.

Main Uses

  • Ring spanners are best in situations demanding secure grip and precision. Their enclosed head prevents slipping and provides better leverage for high-torque tightening or loosening.
  • They're ideal for tasks like assembling furniture with critical joint connections, working on engines or machinery, or any application where accuracy and controlled force are crucial.
  • Compared to open-ended spanners, they are:
  1. Less prone to slippage and rounding off nut edges.
  2. Makes tightening and loosening easier, especially for high-torque situations.
  3. Can sometimes reach nuts in confined spaces due to the enclosed head design.

Benefits

  • Ensures controlled turning and prevents accidental slippage.
  • The enclosed head protects the nut and spanner from damage.
  • Works with various nut and bolt shapes and sizes

Pros:

  • These enclose the fastener on all sides, providing a more secure grip compared to open-ended spanners. This reduces the risk of slipping and damaging the fastener.
  • They allow for more torque to be applied to the fastener without the risk of slipping, making them suitable for dealing with stubborn or tightly-fastened nuts and bolts.
  • This design helps distribute force evenly around the fastener, reducing the likelihood of rounding off the corners of nuts and bolts. 
  • Ring spanners typically have a different-sized opening at each end, offering more versatility and functionality in a single tool

Cons:

  • The enclosed design of ring spanners can make them less suitable for use in tight or confined spaces compared to open-ended spanners. They require more space to fit around the fastener.
  • They take slightly longer to apply to a fastener compared to open-ended spanners due to the need to slide the spanner over the fastener.
  • When working in confined spaces, the fixed angle of the ring spanner might restrict the range of motion or make it challenging to reach certain fasteners at different angles. 
  • While some ring spanners offer different sizes at each end, there might still be limitations in covering a broad range of fastener sizes compared to adjustable spanners.

3. Offset Ring Spanners

Offset Ring Spanners Set

Offset ring spanners are like the special forces of the wrenching world, tackling nuts and bolts where their straight-on normal ring spanners simply can't reach. Unlike regular ring spanners with their straight heads, offset ring spanners have heads bent at an angle (usually 15° or 75°). This bend allows them to access nuts and bolts in tight spaces where a straight spanner would hit obstacles like pipes, beams, or other components. They come in the same size range as regular ring spanners (typically 6mm - 22mm in the UK) and are usually available individually or in dedicated sets.

Main Uses

  • Working on car engines or machinery with congested compartments.
  • Disassembling furniture with hidden nuts tucked away in tight corners.
  • Reaching nuts behind pipes or cables in plumbing and electrical work.
  • Any situation where a straight ring spanner would hit an obstacle, preventing access.

Benefits

  • The angled head grants access to nuts in impossible-looking spaces, saving frustration and time.
  • Similar to regular ring spanners, they offer a secure grip and controlled turning for accurate tightening or loosening.
  • The enclosed head protects the nut and spanner from damage, even in tight spaces.

Pros:

  • The angled head allows you to reach nuts and bolts in tight spaces where straight spanners wouldn't fit. This is a lifesaver when working on engines, machinery, furniture, behind pipes, or in any cramped area.
  • Similar to regular ring spanners, offset versions offer a snug fit around the nut for secure grip and controlled turning, ensuring accurate tightening or loosening.
  • The enclosed head protects both the nut and the spanner from damage, even in tight spaces where bumps and scrapes are more likely.
  • While primarily used for accessing hard-to-reach nuts, offset spanners can still handle many tasks suitable for regular ring spanners.
  • By providing access to previously unreachable nuts, offset spanners can save you significant time and frustration compared to struggling with alternative tools.

Cons:

  • The angled head can be too bulky for some extremely narrow gaps where even an open-ended spanner might be preferable.
  • Compared to regular ring spanners, offset versions typically have a smaller size range, focusing on the most common sizes needed in tight spaces. This means they might not be suitable for every nut you encounter.
  • Due to their specialized design and limited production compared to regular ring spanners, offset versions can sometimes be slightly more expensive.
  • They are less likely to be included in general spanner sets compared to regular ring spanners, so you might need to purchase them individually.

4. Combination Spanners

combi spanner

Combination spanners, also known as combi spanners in the UK. This type of spanner has one open end and a ring end, and hence the name a combination or combi spanner. One end features an open jaw, similar to an open-ended spanner, allowing for quick access and turning.

The other end boasts a fully enclosed ring head, resembling a ring spanner, providing secure grip and precision tightening or loosening.
Combination spanners typically come in the same size range as their individual counterparts (6mm - 32mm in the UK) and are available individually or in convenient sets.

Main Uses

  • Use the open end for fast access and turning, like tightening loose nuts.
  • Switch to the ring end for secure grip and controlled tightening or loosening when more force is needed.
  • The compact design allows them to fit in tight spots where separate open-ended and ring spanners might struggle.
  • Carrying one combination spanner eliminates the need for two separate tools, saving space and weight in your toolbox.

Benefits

  • Two tools in one, offering both fast access and secure grip for varied tasks.
  • Reduces tool changes and saves time during projects.
  • Ideal for carrying around or working in tight spaces.
  • Buying one combination spanner is often cheaper than purchasing separate open-ended and ring spanners of the same size.

Pros:

  • They give more versatility to tackle different types of nuts and bolts with the same tool.
  • The open-ended side provides easier access in tight spaces, while the ring end offers better torque and grip, making it suitable for applications where more force is needed.
  • Similar to ring spanners, the enclosed design of the ring end minimizes the risk of slippage and damage to the fastener compared to open-ended spanners. 

Cons:

  • While the open-ended side is useful for accessibility, the ring end may still pose limitations in extremely tight or hard-to-reach spaces.
  • Similar to individual open-ended or ring spanners, each combination spanner covers one size. Users may need multiple combination spanners to cover a broad range of fastener sizes.
  • While the ring end provides better torque compared to the open end, dedicated ring spanners might offer even greater torque due to their design. 

5. Flare Nut Spanners

DURATECH Flare Nut Spanner Set

These specialised spanners have U-shaped jaws with rounded edges designed to grip and turn flared nuts commonly found in plumbing and gas lines. Unlike regular spanners, their jaws have rounded edges to prevent damage to the delicate flare, ensuring a leak-free seal.

Flare nut spanners are essential tools for plumbers, gas engineers, and DIY enthusiasts working with gas and fluid lines. While not everyday tools, their ability to protect delicate flared nuts and ensure leak-free connections makes them invaluable for specific tasks.

Main Uses

  • Tightening and loosening flared nuts on gas pipes, brake lines, refrigeration systems, and hydraulic lines.
  • Preventing damage to the flared edges, essential for maintaining leak-free connections.
  • Working in tight spaces where regular spanners might struggle due to their bulkier design.

Benefits

  • Their design minimises the risk of rounding or damaging the delicate flare, essential for maintaining leak-free connections.
  • The U-shaped jaws provide a firm grip on the flared nut, preventing slippage and ensuring proper torque application.
  • Available in various sizes to handle different flared nut diameters commonly used in plumbing and gas applications.
  • They are often slimmer than regular spanners, making them suitable for working in tight spaces.

Pros:

  • They have a very compact design and secure grip
  • These are slimmer than regular spanners, making them suitable for working in tight spaces.
  • Ideal for working on gas and many types of hydraulic fluid lines. 

Cons:

  • Not as versatile as general-purpose spanners and might not be needed for everyday tasks.
  • Typically focused on the most common flared nut sizes used in plumbing and gas work, so they might not fit all applications.
  • Due to their specialised design and limited use compared to regular spanners, they can sometimes be slightly more expensive.

6. Socket Spanners

DURATECH Double Ended Hex Spanner

Socket spanners, also known as socket sets in the UK, offer interchangeable sockets that fit onto a ratchet handle for turning various nut and bolt shapes and sizes. This modular system provides ultimate versatility in a compact kit. Socket spanners are a powerful addition to any toolbox, offering exceptional versatility and convenience.

Their wide range of applications, compact design, and interchangeable sockets make them a go-to choice for both basic DIY tasks and professional work. However, their initial cost and potential for losing small parts should be considered.

Main Uses

  • They are mainly used for tightening and loosening various nuts and bolts across different tasks, from car repairs to furniture assembly.
  • Reaching nuts in tight spaces due to the slim profile of sockets compared to traditional spanners.
  • They can handle a wide range of nut and bolt shapes, including hex, square, spline, and torx, thanks to interchangeable sockets.
  • They apply controlled torque with the help of different ratchet mechanisms (standard, quick-release, torque wrench).

Benefits

  • One set covers multiple sizes and shapes, reducing the need for individual spanners.
  • Sockets and handles store efficiently, saving space in your toolbox.
  • Slim sockets reach tight spaces where traditional spanners struggle.
  • Different ratchet mechanisms offer standard tightening/loosening, quick action, or controlled torque application.
  • Sockets are typically made from strong materials like chrome vanadium steel, ensuring longevity.

Pros:

  • Ideal for DIY enthusiasts and professionals needing a versatile tool set.
  • Easier to use than individual spanners for many tasks.
  • Suitable for working in tight spaces.
  • Can be expanded with additional socket sets for even more coverage.

Cons:

  • Initial cost can be higher compared to individual spanners, especially for larger sets.
  • Requires keeping track of multiple sockets and the handle.
  • Sockets might not be suitable for highly damaged or rounded nuts. 
  • Not as effective for applying very high torque as some individual spanners.

7. Ratchet Spanners

Ratchet Spanners

Ratchet spanners combine the convenience of a ratchet mechanism with the handiness of a standard spanner, allowing for fast and efficient tightening and loosening of nuts and bolts without needing to remove the tool completely.

They are a valuable addition to any toolbox, especially for tasks requiring speed, efficiency, and minimal hand strain. Their innovative design makes them ideal for repetitive work in tight spaces. However, their initial cost, limitations in high-torque situations, and potential for losing small parts should be considered before purchase.

Main Uses

  • Tightening and loosening nuts and bolts quickly, ideal for repetitive tasks or situations where access is limited.
  • Working in tight spaces where hand movement is restricted, as the ratchet mechanism requires minimal back-and-forth motion.
  • Applying controlled torque with some models featuring adjustable torque settings.
  • Handling various nut and bolt sizes with interchangeable heads on some models.

Benefits

  • The ratchet mechanism allows for continuous turning without removing the spanner, saving time and effort.
  • Slim profiles often fit in tight spaces where regular spanners might struggle.
  • Minimal hand movement required, minimising fatigue during repetitive tasks.
  • Adjustable torque settings on some models ensure proper tightening without overdoing it.
  • Interchangeable heads on some models offer the flexibility of multiple spanner sizes in one tool.

Pros:

  • Ideal for professionals and DIY enthusiasts who value speed and efficiency.
  • Easier on the hands compared to regular spanners, especially for repetitive tasks.
  • Can be compact and suitable for tight spaces.
  • Some models offer interchangeable heads for added versatility.

Cons:

  • Can be initially more expensive than regular spanners.
  • Not as strong as some individual spanners for high-torque applications.
  • Requires keeping track of the ratchet mechanism, which can be bulky.
  • Interchangeable heads (in select models) might add complexity and potential for losing parts.

8. Adjustable Spanners

Silverline Adjustable Wrench Set 3pce

These handy tools feature a sliding jaw that adjusts to various nut sizes, eliminating the need for a whole set. They're great for quick fixes and odd jobs but not ideal for high-torque applications. They are often referred to as "adjustable wrenches" or "shifting spanners," and the name given varies in different regions in the UK, and indeed throughout the world.

Adjustable spanners are valuable tools for versatility and convenience, particularly for basic tasks or situations where multiple sizes are needed. However, their limitations in precision, torque, and potential for wear should be considered when tackling demanding jobs or requiring high accuracy. They are best used as a complement to dedicated spanners for specific sizes and best performance.

Main Uses

  • Used for tightening and loosening nuts and bolts of various sizes, particularly useful when dealing with unknown or mixed sizes.
  • Really handy for quick adjustments and repairs where carrying a full spanner set might be impractical.
  • Can be used for working in tight spaces where bulky individual spanners struggle to fit.
  • They serve as an excellent backup tool when the exact size spanner is unavailable.

Benefits

  • Adapts to various nut and bolt sizes, reducing the need for multiple spanners.
  • One tool does the job of many, saving space in your toolbox.
  • Quick adjustments eliminate the need to switch between different spanners.
  • More affordable than purchasing individual spanners for various sizes.
  • Can sometimes handle bolts and nuts with slightly irregular shapes.

Pros:

  • Ideal for beginners, DIY enthusiasts, and professionals who need a basic, adaptable wrench.
  • Great for quick fixes and tasks where the exact size is unknown.
  • Convenient for carrying around or working in tight spaces.
  • Cost-effective option compared to buying individual spanners.

Cons:

  • Not as precise as dedicated spanners for specific sizes, potentially leading to rounded nut edges.
  • Not suitable for high-torque applications due to potential slippage or jaw movement.
  • The adjustable mechanism can hinder access in very tight spaces compared to slimmer spanners.
  • The adjusting mechanism can wear over time, affecting accuracy and grip.

9. Box Spanners

box spanner set

Box spanners, also known as box-end wrenches, feature fully enclosed heads that envelop the entire nut or bolt head, offering exceptional grip and leverage for high-torque applications in demanding tasks. Box spanners are essential tools for tackling high-torque jobs and stubborn nuts and bolts where regular spanners fall short.

They have a very robust design, exceptional grip, and the leverage they deliver make them ideal for professionals and DIY enthusiasts working on demanding tasks. However, their bulkiness, limited size range, and higher cost should be considered before purchase.

Main Uses

  • Tightening and loosening large nuts and bolts requiring high torque, ideal for car repairs, machinery maintenance, and heavy-duty projects.
  • Working with stubborn or seized nuts and bolts where regular spanners might struggle.
  • Applying controlled torque with some models featuring torque wrench functionality.
  • Reaching recessed nuts and bolts due to the slim profile of the box head.

Benefits

  • Enclosed head prevents slippage and ensures maximum torque transfer, even on worn or damaged nuts.
  • Long handles and deep box heads provide increased leverage for tackling tough jobs.
  • Robust construction withstands high forces and demanding environments.
  • Adjustable torque settings on some models ensure proper tightening without overdoing it.
  • Can sometimes reach recessed nuts and bolts inaccessible to regular spanners.

Pros:

  • Ideal for professionals and DIY enthusiasts working on high-torque applications.
  • Excellent grip and leverage minimise effort and prevent slippage.
  • Durable design built to last in demanding environments
  • Some models offer the versatility of interchangeable heads and torque control.

Cons:

  • Can be bulky and heavy, making them less suitable for tight spaces or delicate tasks.
  • Not as versatile as adjustable spanners, requiring specific sizes for each nut or bolt.
  • Higher cost compared to regular spanners, especially for larger sets.
  • Interchangeable heads (in select models) might add complexity and potential for losing parts.

10. Torque Wrenches

Torque Wrench Set

Torque wrenches are specialised tools that apply a pre-set amount of torque to nuts and bolts, ensuring they are tightened to the correct specification with utmost precision. This prevents overtightening or under tightening, crucial for safety and optimal performance in critical applications. They are invaluable tools for anyone working on tasks where precise torque application is crucial.

While they are an investment, the benefits of preventing damage, ensuring safety, and achieving the best performance often outweigh the cost. However, their specialised nature, calibration requirements, and potential for misuse should be considered before purchase.

Main Uses

  • Tightening critical components in engines, machinery, automotive repairs, and other situations where precise torque is essential.
  • Preventing damage to delicate components that can occur from overtightening.
  • Ensuring consistent and reliable performance by applying the manufacturer's recommended torque specifications.
  • Verifying the tightness of existing bolts, especially in safety-sensitive applications.

Benefits

  • Eliminates the risk of over or undertightening, ensuring optimal performance and safety.
  • Consistent torque across multiple fasteners, guaranteeing reliable results.
  • Protects delicate components from damage caused by excessive force.
  • Ensures you're following manufacturer recommendations for proper assembly and maintenance.
  • Available in various types (click, digital, beam) and torque ranges to suit different applications

Pros:

  • Essential for professionals and DIY enthusiasts working on critical tasks.
  • Promotes safety and prevents costly damage from incorrect torque application.
  • Offers peace of mind by ensuring you're following proper procedures.
  • Versatile range of types and torque options available for various needs.

Cons:

  • Higher cost compared to regular spanners.
  • Requires calibration at regular intervals to maintain accuracy.
  • Potential for misuse if not used correctly.
  • Can be bulky and less convenient for quick tasks compared to regular spanners.

My Summary

If you didn't know a lot about spanners, hopefully you now have a much better understanding. If you have any further questions about spanners, their different types, or their suitability for your specific needs, feel free to ask in the comments below! I'm happy to help you choose the right tool for precision tightening.

For a homeowner in the UK, who doesn't regularly use or need a spanner, then owning an adjustable spanner is the best option. In many cases, an adjustable spanner will allow you to fix bicycles, replace washing machine hoses and be able to tighten and loosen most nuts and bolts.

For those of us who like to do a little more DIY, then an adjustable spanner set, along with a good socket set, is likely all that you will ever need to own. I own both of these and have yet to find something around the home or yard that I can't deal with, using one of these two options.

For professionals, the type of spanners will vary by the trade. Plumbers, car mechanics and some engineers will need a much bigger variety of these types of spanners. At least they have lots of choices and they will already have learned which types they need during their apprentice days or when learning their trade.

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