Try square buying guide: choose the right size and scale
Updated: October 2026
You are buying a square for shelves, trim or small joinery, and the first decision is not whether the stock contains a vial. It is whether the blade reaches across the work you actually mark. This try square buying guide puts useful length first, then asks whether the scale is readable, the joint is secure and the listing describes one consistent product. You can see the five current prices and product details in the [try square comparison](/hub/measuring-and-marking-tools/try-square). Use this guide to decide which trade-offs matter before paying extra for a scriber, a 45° face or another secondary feature.
You are buying a square for shelves, trim or small joinery, and the first decision is not whether the stock contains a vial. It is whether the blade reaches across the work you actually mark.
You are buying a square for shelves, trim or small joinery, and the first decision is not whether the stock contains a vial. It is whether the blade reaches across the work you actually mark. This try square buying guide puts useful length first, then asks whether the scale is readable, the joint is secure and the listing describes one consistent product. You can see the five current prices and product details in the try square comparison. Use this guide to decide which trade-offs matter before paying extra for a scriber, a 45° face or another secondary feature.
Our top picks
| Badge | Product | Stated length | Scale | Joint | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  WORKPRO WORKPRO 200 mm try square | 200 mm | Both sides, mm and in | Three pins | 9.2 | about £11.99 | View offer |
| Preis-Tipp |  S & S PRODUCTS S & S 150 mm try square | 150 mm | Metric and imperial | Punch indents | 8.2 | about £4.49 | View offer |
| Alternative |  Prexiso PREXISO 250 mm try square | 250 mm | Metric, both sides | Not stated | 8.7 | about £16.99 | View offer |
On this page
Start with the board, not the vial
A 150 mm try square suits narrow rails, battens and trim. On a 190 mm flooring plank it cannot cross the face in one pass. The S & S at £4.49 makes sense only when that short reach matches the work.
For general DIY, 200 to 250 mm is the useful middle. WORKPRO states 200 mm. PREXISO states 250 mm and adds a vial, 45°, a scriber and notches. Those extras do not compensate for a blade shorter than the workpiece.
A stated 300 mm blade, on the Gunpla and the Presch, reaches further and shows a flip-test error more clearly. Extra length is wasted if most marks are only 80 mm. Measure the widest face you commonly cross. The best try square guide matches the five listings to likely users.
Read the size fields against each other
An amazon.co.uk title is not enough evidence of size. Compare the title, graduation range and dimensions before you order. When those lines disagree, treat the size as uncertain and check the product on arrival.
S & S says 150 mm in the title, but its graduation field says 150 millilitres. Gunpla says 300 mm or 12 inches while its dimensions field says 30 × 15 mm. WORKPRO states 200 mm, yet another field gives 15 × 2.7 cm. Presch's title says 300 mm, while the graduation field says 18 cm. PREXISO is more consistent at 250 mm, although the material attribute and a review disagree over aluminium or steel.
A conflicting field is a reason to inspect what arrives against a trusted rule. If the description was material to your choice and the goods do not match it, keep the order evidence.
Choose the scale and joint before the extras
A clear metric scale is more useful for UK DIY than marks you cannot read from the working side. WORKPRO claims metric and imperial graduations on both sides. On the Gunpla, one review says centimetres are on the outer edge and inches on the inner. A printed number does not tell you whether the blade is perpendicular to the stock.
The joint determines whether 90° stays 90°. S & S reviews describe punch indents, looseness and glue. A Gunpla reviewer says a rivet came off. WORKPRO states a three-pin joint. A stock that rocks against the blade is a stop. Do not treat owner-added adhesive as a normal adjustment.
Only then value extras. A 45° face helps with simple mitres. A short vial is not a spirit level. PREXISO's scriber and 5 mm notches can speed repeated marks, although a knife can damage its aluminium edge. Try square vs combination square explains when a sliding head is the better buy.
Understand what these listings do not claim
None of the five listings states BS 3322 or BS 939. BS 3322 covers carpenters' squares and bevels. BS 939 applies to engineer's squares with defined grades. The word engineer in a title does not establish compliance.
Hardwood-stock try squares and graded all-metal engineer's squares are different purchases. No material makes an unchecked joint accurate. After delivery, inspect for burrs, then use the draw-and-flip method in how to check a try square. A star rating cannot tell you whether the tool in the parcel is at 90°.
Common questions
What size try square should you buy first?
For mixed household DIY, 200 to 250 mm is a useful compromise between reach and handling. Choose 150 mm if your work is mostly trim or small components, and consider 300 mm for wide shelves or boards. Measure the faces you normally mark before choosing. Overall board length is irrelevant.
Is 150 mm enough for flooring?
It depends on plank width. A 150 mm blade cannot cross a board wider than 150 mm in one pass, so you would extend the line or mark from another face. That adds scope for misalignment. A 200, 250 or 300 mm square is usually more convenient for wider flooring.
Does a vial replace a spirit level?
No. A vial in a short square can give a quick indication over the stock's limited length. It does not offer the long reference surface of a dedicated spirit level. Use it as an extra check, not as the main tool for levelling a shelf or a long unit.
Is a 45° face worth paying for?
It is useful when you regularly mark simple mitres and the feature does not force a compromise on blade length or joint quality. It does not provide a sliding depth gauge or a repeatable offset. If those jobs matter, a combination square is the more suitable mechanism.
What should you do when listing sizes disagree?
Save the listing or order details, confirm the supplied blade with a trusted rule and check accuracy before use. Do not assume a title is correct when the dimensions or graduation fields conflict. If the delivered product does not match a material description, use the retailer's returns process promptly.
Does engineer's square in a title mean BS 939?
No. BS 939 grades are a specific claim, not a synonym created by a product title. None of these five listings states that standard. Buy a graded engineer's square from a source that declares the grade when the work needs a precision reference rather than ordinary timber marking.
Related pages
Sources
Public UK sources for this comparison. Prices, stars and review counts are the amazon.co.uk figures in the listing files, not a live reload.
- BSI, BS 3322:1981 — carpenters' squares and bevels (retrieved 16 October 2026)
- BSI, BS 939:2007 — engineers' squares (retrieved 16 October 2026)
- Wonkee Donkee Tools — engineer's square accuracy (retrieved 16 October 2026)
- Wonkee Donkee Tools — how to use a try and mitre square (retrieved 16 October 2026)
- Wood Workers Workshop — flip test (retrieved 16 October 2026)
- Axminster — measuring and marking (retrieved 16 October 2026)
- Axminster — types of woodworking square (retrieved 16 October 2026)
- Consumer Rights Act 2015, section 22 (retrieved 16 October 2026)
- Faithfull — carpenters' try squares (retrieved 16 October 2026)