The adjustable spanner is one of the most-used tools on any worksite, workshop, or maintenance kit — and one of the most misused. Used correctly, it handles a huge range of fastener sizes with a single tool. Used incorrectly, it rounds corners, damages chrome fittings, and occasionally takes out a set of knuckles.
This guide covers what adjustable spanners are, the terminology Australians use for them, how they work, the main types and variants, how to read and choose the right size, the correct technique, what to look for in quality, and when to reach for something else instead. Whether you are equipping a workshop, restocking a service van, or just trying to understand what you are looking at on the shelf, this is the reference.
What Australians Call It: The Terminology
The same tool goes by several names depending on where you are:
| Term | Where it is used |
|---|---|
| Shifter | Dominant informal term in Australia and New Zealand — used on virtually every job site |
| Shifting spanner | Formal AU/NZ written variant — appears in specifications and tool catalogues |
| Adjustable spanner | Standard AU/UK written term |
| Adjustable wrench | US and Canadian term — used in imported product documentation |
| Crescent wrench | US generic term derived from the Crescent Tool Company brand — not widely used in Australia |
| Monkey wrench | Originally a different tool (F-shaped, jaws perpendicular to handle) — the term is sometimes used loosely but is not the same thing |
If you are ordering tools for an Australian worksite, "adjustable spanner" or "shifting spanner" are the correct written terms. In conversation, "shifter" is standard. Online search will find the same tools under "adjustable wrench" due to US-dominated product listings.
How an Adjustable Spanner Works
An adjustable spanner has two jaws: a fixed jaw that is machined as part of the tool head, and a moveable jaw that slides along a rack built into the jaw throat. A knurled worm gear (the thumb wheel on the side or base of the head) meshes with teeth on the moveable jaw. Rotating the worm gear opens or closes the jaw gap.
The moveable jaw is held in position by the friction of the worm gear thread — it is not locked. Under load, the jaw can creep if the fit is not snug against the fastener. This is the fundamental difference from a fixed spanner: the fit is adjustable but it is never as positive as a correctly sized ring or open-end spanner. It is also why jaw quality and worm gear quality matter — in cheap tools, the worm wears quickly and the jaw develops slop.
The thumb wheel is typically accessible from both sides of the spanner head, allowing adjustment with one hand while the other holds the fastener steady.
Types of Adjustable Spanner
Standard adjustable spanner
The classic form: a relatively thin head with one fixed jaw and one moveable jaw, adjusted by a side-mounted or base-mounted worm wheel. The jaw throat depth is proportional to jaw opening — a 200mm spanner opens to around 25mm, a 300mm to around 34mm. This is the most widely stocked type and covers the majority of industrial, workshop, and maintenance tasks.
Wide-jaw adjustable spanner
A wider jaw opening relative to tool length — the Irega 92 is an example, designed to open further than a standard spanner of the same nominal length. Useful for plumbing and gas work where large flange nuts, large BSP fittings, or oversize hex forms are common. The wider jaw-to-handle ratio does reduce rigidity slightly compared to a standard-profile head.
Reversible jaw adjustable spanner
The Bahco RAW (Reversible Adjustable Wrench) pattern — the moveable jaw can be flipped 180° to either side of the handle. Conventional adjustable spanners have the moveable jaw on one side only, which means you are either pulling toward the fixed jaw or pushing toward the moveable jaw depending on your body position. A reversible jaw lets you pull toward the fixed jaw in either direction without repositioning yourself or the tool. Particularly useful in confined spaces where you cannot choose your stance relative to the fastener. Bahco's reversible jaw range is stocked at AIMS.
Self-setting spanner (Joker pattern)
The Wera 6004 Joker is the most well-known example. A spring-loaded lower jaw automatically seats against the fastener flat when the tool is placed on the nut or bolt head — no thumb wheel adjustment needed. The spanner self-sizes, engages, and can be pulled immediately. Faster for repetitive work. The self-setting mechanism also includes a secondary contact point that helps prevent rounding on worn fasteners. Premium price, but a genuine productivity tool for high-repetition use.
Ratcheting adjustable spanner
Combines the variable jaw of an adjustable spanner with a ratchet mechanism in the head, allowing continuous rotation in one direction without removing and repositioning the tool on the fastener. Best suited to bolt-down work with moderate torque requirements — not appropriate for very high torque where ratchet pawl engagement may be the limiting factor. Available as dedicated adjustable ratchet spanners (200mm is a common size) and as an attachment feature on some adjustable spanners.
Pipe wrench (for comparison)
A pipe wrench (Stillson wrench) looks superficially similar to a large adjustable spanner but is a different tool with a different purpose. The key differences:
- Jaws: A pipe wrench has serrated, toothed jaws designed to bite into round, smooth, or cylindrical surfaces — pipes, conduit, rods. An adjustable spanner has smooth, flat jaws designed for flat-faced fasteners (hex bolts, square nuts). The teeth on a pipe wrench will damage hex fasteners and chrome fittings.
- Jaw angle: Pipe wrench jaws are angled so the bite tightens as torque is applied in one direction and releases in the other — directional grip only. Adjustable spanner jaws are parallel and grip in both directions.
- Application: Use a pipe wrench for pipes, conduit, large threaded rods, and round fittings. Use an adjustable spanner for hex, square, or flat-sided fasteners. Do not substitute one for the other.
Size Guide: What the Number Actually Means
The size number stamped on an adjustable spanner is the overall tool length in millimetres, not the jaw opening capacity. A 200mm adjustable spanner is 200mm long from end to end. The jaw opening it can achieve is a secondary specification that varies between manufacturers — typically expressed as the maximum jaw opening in mm.
This is one of the most common points of confusion when buying adjustable spanners. If you need to fit a fastener of a specific size, check the manufacturer's maximum jaw opening specification, not just the tool length.
| Nominal length | Typical max jaw opening | Common applications |
|---|---|---|
| 100mm (4") | ~14mm | Electronics, instrumentation, small fittings, very confined spaces |
| 150mm (6") | ~19mm | Light workshop, fasteners to M12, precision equipment |
| 200mm (8") | ~25mm | General purpose — the most common site and workshop size. Covers the majority of M8–M18 fasteners. |
| 250mm (10") | ~30mm | Medium-heavy work, plumbing fittings, automotive, M20–M24 fasteners |
| 300mm (12") | ~34mm | Heavy industrial, large plumbing and gas fittings, large structural fasteners |
| 375mm (15") | ~43mm | Industrial pipework, scaffold, large flange work |
| 450mm (18") | ~52mm | Large industrial fittings, heavy gas and water mains work |
Jaw opening figures are typical. Check the manufacturer's specification for the exact maximum jaw opening on the model you are selecting.
For most tradies and maintenance workers, a 200mm is the primary carry size — it handles the widest range of everyday fasteners. A 300mm alongside it covers heavy plumbing, gas, and industrial work. If space or weight is a constraint, a single 250mm covers both roles adequately.
How to Use an Adjustable Spanner Correctly
More nuts and bolt heads are rounded by incorrectly used adjustable spanners than by any other single cause. The correct technique is straightforward but not intuitive until you know it.
1. Set the jaw snug before applying force
Adjust the worm wheel until the jaws grip the flat faces of the nut or bolt head firmly, with zero play or wobble. The jaw should contact the fastener on at least two opposing flat faces. Any slop in the fit means the jaw will rotate slightly under load before the flat contacts, and the corners of the fastener take the impact — that is how corners round off.
2. Orient the fixed jaw in the direction of pull
The fixed jaw is integral to the tool head and is structurally stronger than the moveable jaw. Always position the spanner so the fixed jaw is on the side that takes the load — meaning you pull toward the fixed jaw, not toward the moveable jaw.
In practice: when tightening (clockwise), the fixed jaw should be on the upper/leading face of the fastener as you pull the handle toward you. When loosening (anticlockwise), flip the spanner 180° so the fixed jaw is again on the side you are pulling toward. This takes one second and significantly reduces the chance of the jaw spreading under load.
3. Pull, don't push
Always pull the spanner handle toward you rather than pushing it away. Pulling gives more control over the force applied, and if the spanner slips, your hand moves away from the work rather than into it. Pushing means a slip sends your knuckles directly into the workpiece — the classic "knuckle-buster" injury. If the geometry of the job forces a push, brace your palm against the back of the handle rather than wrapping your fingers around it.
4. No extensions
Do not extend the handle with a pipe or bar to get more leverage. An adjustable spanner is not designed for the torque that a cheater bar produces, and the worm gear joint will open under the load, rounding the fastener and potentially causing the tool to fail. If you need more torque, use a ring spanner or a socket and torque wrench.
5. Recheck the jaw fit after each reposition
Every time you lift and reposition the spanner, check the jaw is still snug. Worm gears, especially on mid-range tools, can lose their set slightly during a stroke. A quick half-turn check before each pull takes less than two seconds and prevents rounding.
When working on a component that tends to rotate or shift under spanner load, clamp it securely in a bench vice before applying the spanner. A vice eliminates workpiece movement, frees both hands, and lets you direct full force to the fastener rather than fighting to hold the work still.
Material and Quality: What to Look For
Adjustable spanner quality varies enormously. The price gap between a cheap no-name and a professional-grade Bahco or Irega is real and reflects in tool life, jaw accuracy, and worm gear durability.
Chrome-vanadium (Cr-V) steel
Chrome-vanadium is the industry-standard material for professional-grade adjustable spanners. It is harder, tougher, and more wear-resistant than plain carbon steel, which matters most at the worm gear interface and the jaw faces. All Bahco and Irega tools are Cr-V drop-forged — the drop-forging process produces a denser, stronger grain structure than casting.
Chrome finish vs black finish
Chrome-plated spanners resist surface corrosion and are easy to clean. Black-finish (phosphated or oxide) spanners have a non-reflective surface, preferred in some professional and automotive contexts. Both finishes are compatible with Cr-V steel and perform equivalently in standard industrial use. Black finish tools are not inherently higher grade — it is a surface treatment, not a material quality indicator.
Worm gear quality — the key differentiator
The worm gear (the small wheel and the rack it meshes with) is the first component to fail on a cheap adjustable spanner, and the reason cheap spanners develop slop early. On quality tools, the worm is precision-cut, the fit is tight, and there is minimal backlash. You can assess this by opening the jaw to mid-range and checking for play — push and pull the moveable jaw with your thumb. A quality tool should have essentially zero free movement. If there is perceptible play, the worm gear is already worn or poorly manufactured.
AS/NZS 1700 compliance
AS/NZS 1700 (Hand Tools: Spanners and Wrenches) sets dimensional and material requirements for spanners sold in Australia and New Zealand. Tools compliant with this standard will have size markings, material grade, and jaw dimensional tolerances that meet the specification. Look for the standard reference in product documentation for professional-grade tools.
When Not to Use an Adjustable Spanner
The adjustable spanner is a versatile tool, but there are situations where it is the wrong choice:
- Precision torque work — an adjustable spanner cannot be used with a torque wrench. For any fastener with a specified torque, use a socket set.
- High-torque or high-repetition work — ring spanners and socket sets provide a six-point engagement around the full hex, distributing load more effectively and dramatically reducing rounding risk under high torque. Use them for critical structural or high-load fasteners.
- Confined spaces where full jaw seating is not possible — if the geometry means only one or two jaw faces can contact the fastener properly, do not use an adjustable spanner. Use the correct fixed-size tool.
- Soft material fasteners — brass fittings, aluminium fixtures, and plastic fasteners are particularly vulnerable to rounding under even a slightly misadjusted adjustable jaw. A correctly sized fixed spanner is safer.
- Round, cylindrical or pipe work — use a pipe wrench. An adjustable spanner's smooth jaws cannot grip round objects reliably.
The adjustable spanner earns its place in every kit for its flexibility across a range of fastener sizes. Use it for that. For precision, high-torque, or specialty applications, reach for the specific tool.
Adjustable Spanners at AIMS Industrial
AIMS stocks professional-grade adjustable spanners from Bahco and Irega — two of the most respected hand tool brands for industrial and trade use.
- Bahco adjustable spanners — including the reversible jaw (RAW) range, chrome and black finish, from compact 100mm to heavy-duty 300mm. Bahco Cr-V tools are Swedish-designed and meet AS/NZS 1700.
- Irega adjustable spanners — Spanish-manufactured professional tools with standard and wide-jaw profiles in 250mm and 300mm. The Irega 92 wide-jaw is particularly suited to plumbing and gas work with its extended jaw opening.
- Ratcheting adjustable spanners — available for repetitive fastening work where ratchet action reduces cycle time.
Browse the full adjustable spanner range at AIMS Industrial
For broader spanner selection, see our complete Types of Spanners Guide.
Frequently Asked Questions
What do Australians call an adjustable spanner?
In Australia and New Zealand, the most common informal term is shifter. The formal written term is shifting spanner or adjustable spanner. In the US and Canada the same tool is called an adjustable wrench or informally a crescent wrench (after the Crescent Tool Company brand). All these terms refer to the same basic tool: a spanner with one fixed jaw and one moveable jaw adjusted by a worm gear. "Monkey wrench" is sometimes used loosely in Australia but technically refers to a different F-shaped wrench where the jaws are perpendicular to the handle.
What is an adjustable spanner used for?
An adjustable spanner is used to tighten or loosen hex (hexagonal) nuts and bolts, square-head fasteners, and flat-sided fittings across a wide range of sizes — using one tool instead of a full set of fixed spanners. Common applications include plumbing fittings, electrical conduit, machinery maintenance, automotive work, and general construction and site work. It is not suitable for round or cylindrical objects (use a pipe wrench), precision torque applications (use a socket and torque wrench), or high-repetition high-torque work (use ring spanners or sockets).
What is a Joker or self-setting spanner?
A self-setting spanner (the Wera 6004 Joker is the best-known example) has a spring-loaded lower jaw that automatically seats against the fastener flat when the tool is placed on the nut or bolt head — no thumb wheel adjustment required. The spanner senses the fastener size and grips immediately. A secondary contact point in the jaw profile also helps prevent rounding on worn or damaged fasteners. Self-setting spanners are faster for high-repetition work and eliminate the step of manually adjusting the worm gear. They carry a premium price but are a genuine productivity tool for professional trade use.
What is the best brand of adjustable spanner for professional use?
Bahco and Irega are consistently rated among the best professional-grade adjustable spanners for industrial and trade use in Australia. Bahco (Swedish-designed, drop-forged Cr-V) is well established across maintenance, mechanical, and construction trades. Irega (Spanish-manufactured, professional grade) has a strong following in plumbing and gas fitting for its wide-jaw models. Both meet or exceed AS/NZS 1700 requirements. For premium self-setting tools, Wera's Joker range is the benchmark. All three are available through professional trade suppliers.
What does the size number on an adjustable spanner mean?
The size number stamped on an adjustable spanner is the overall tool length in millimetres, not the jaw opening capacity. A 200mm adjustable spanner is 200mm long from end to end. The maximum jaw opening it can achieve is a separate specification — typically around 25mm for a 200mm tool, 34mm for a 300mm tool, but this varies by manufacturer. If you are selecting a spanner to fit a specific fastener size, always check the manufacturer's listed maximum jaw opening, not just the nominal tool length.
Which size adjustable spanner should I buy?
For general-purpose site and workshop use, a 200mm is the most practical single size — it covers the majority of everyday fasteners from M8 to approximately M18 and is comfortable to carry and use in most working positions. Add a 300mm if you are doing plumbing, gas, or heavy industrial work requiring a larger jaw opening. If you can only carry one and the work spans a wide range of fastener sizes, a 250mm is a reasonable compromise. For tight-space work or electronics, a 150mm or 100mm compact is useful as a secondary tool.
How do I use an adjustable spanner correctly without rounding a nut?
Four steps: (1) Adjust the worm wheel until the jaws grip the fastener flat faces with zero play or wobble. (2) Position the spanner so the fixed jaw (the jaw that is part of the tool head, not the adjustable jaw) is on the side you will be pulling toward — the fixed jaw is stronger and takes the load. (3) Pull the handle toward you rather than pushing it away — pulling gives more control and reduces injury risk if the spanner slips. (4) Recheck the jaw fit after each reposition. Most rounding happens from a jaw that has developed slop or was not fully set against the fastener before force was applied.
Should I push or pull an adjustable spanner?
Pull toward yourself whenever possible. Pulling gives more control over the force applied, and if the spanner slips, your hand and knuckles move away from the work rather than into it. Pushing means any slip sends your knuckles directly into the workpiece — the classic "knuckle-buster" injury. If the work geometry forces you to push, brace your palm against the back of the handle rather than wrapping your fingers around it so your knuckles are protected if it slips.
What is a reversible jaw on an adjustable spanner?
A reversible jaw adjustable spanner (Bahco RAW pattern) allows the moveable jaw to be flipped to either side of the handle. On a conventional adjustable spanner, the moveable jaw is fixed on one side only. This means that depending on your body position relative to the fastener, you may end up pulling toward the moveable jaw — the weaker side. A reversible jaw eliminates this: no matter which way you are positioned, you can orient the tool so the fixed jaw always takes the load. Particularly useful in confined spaces where you cannot choose your stance. It is a genuine functional improvement, not just a feature.
What is the difference between an adjustable spanner and a pipe wrench?
An adjustable spanner has smooth, flat, parallel jaws designed to grip the flat faces of hex nuts, square bolts, and flat-sided fittings without marking them. A pipe wrench has serrated, toothed jaws that bite into round, cylindrical surfaces — pipes, conduit, and threaded rods — and are designed to grip tighter as torque is applied in one direction. Do not use a pipe wrench on hex fasteners: the teeth will damage the flats and chrome fittings. Do not use an adjustable spanner on round pipe: the smooth jaws cannot grip reliably and the tool will slip under load.
What material should a quality adjustable spanner be made from?
Drop-forged chrome-vanadium (Cr-V) steel is the industry standard for professional-grade adjustable spanners. Chrome-vanadium is harder and more wear-resistant than plain carbon steel, which matters most at the worm gear teeth and jaw faces — the areas that take the most wear. Drop forging produces a denser grain structure than casting, improving overall strength and impact resistance. Look for "Cr-V" or "chrome vanadium" in the product specification. The chrome plating (or black oxide finish) on the surface is a corrosion treatment and does not indicate the underlying steel grade.
When should I use a ring or open-end spanner instead of an adjustable?
Use a ring spanner or socket when: (1) you know the exact fastener size — a correctly fitted ring spanner applies force across all six flats and will not round corners; (2) torque is high or critical — ring spanners handle significantly higher torque than adjustable spanners without jaw spread risk; (3) a specified torque is required — adjustable spanners cannot be used with a torque wrench; (4) repetitive use — sockets and ring spanners are faster and more reliable for high-volume fastening. The adjustable spanner is for situations where you need to span multiple sizes with one tool, the fastener size is unknown, or carrying a full fixed-size set is impractical.
Browse the full AIMS Spanners & Wrenches range for fixed-jaw combination spanners, ring spanners and specialist sizes.