Replacing or upgrading your door hardware can transform the look of a room, but it also brings an unglamorous reality: incorrect measurements could leave you with misaligned knobs, extra holes and a headache. As builders, designers and renovators know, accuracy matters just as much as style. In this guide we explain the three critical measurements - backset, centre‑to‑centre (often abbreviated as C‑to‑C) and door thickness - and show you how to take them like a pro.
What is backset and why does it matter?
Backset is the distance from the edge of the door to the centre of the spindle or lock cylinder. When you’re working with a new door, it’s also the centre point of the hole you will bore to fit the lock. If this measurement isn’t taken accurately, the latch may not extend fully into the striker plate, leading to poor alignment and security.
Hardware Box’s Mucheln range uses a 60 mm backset by default. This is the most common size for modern internal doors in Australia. For some styles we can supply a 45 mm backset - handy if you’re matching older joinery - but please get in touch to confirm availability.
In some cases an extended- backset latch may be required, typically this would be 70mm.
Knowing what you need up front will save you time wasted later!
How to measure backset
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Remove the handle so you can see the bore hole.
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Measure from the door edge to the centre of the spindle or keyhole using a ruler or tape measure. Don’t measure the bore hole itself, as holes are often larger than necessary.
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Record the measurement. It will usually be 45 mm or 60 mm. Imported locks from other regions may vary.
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Check adjustability. Some latches are adjustable. If yours isn’t and the size is wrong, you’ll need a new latch.
Understanding centre‑to‑centre (C‑to‑C) measurements
Centre‑to‑centre refers to the distance between the centres of two mounting points on a piece of hardware. It’s common on Pull handles and cabinet hardware, where it measures the spacing between screw holes. Standard sizes for Mucheln pulls include 96 mm, 128 mm, and 192 mm. Other brands may vary.
To measure, remove one screw and lightly loosen the other so you can measure from the centre of one hole to the centre of the other. If you’re starting from scratch, choose a size that suits the scale of the door or drawer. Always double‑check that your replacement hardware uses the same spacing.
Measuring door thickness
Door thickness determines which latches, bolts and screws will fit properly. Most interior hollow‑core doors in Australia are 35-45mm thick. Measuring is simple: open the door and place a ruler or caliper across the edge. If you’re installing a privacy set or deadbolt, check the manufacturer’s specification for the minimum and maximum door thickness they accommodate. Hardware Box lists the compatible door thickness range for each product to help avoid guesswork.
Additional hardware terms to know
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Tubular latch – A cylindrical mechanism in the door cavity that holds the door shut and allows the latch tongue to retract when the handle is operated. It’s commonly used on non‑locking doors or with a separate privacy snib.
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Striker plate – A metal plate installed on the door jamb that the latch tongue engages with, keeping the door closed and protecting the jamb from wear.
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Spindle – A square metal rod that passes through the latch, connecting the handles on both sides and transferring turning motion. Spindle sizes can vary; ensure you choose one that matches your latch and door thickness.
Step‑by‑step: taking accurate measurements
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Remove the existing hardware.
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Measure backset: door edge to centre of spindle.
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Check bore‑hole diameter: most modern hardware requires a 54‑mm hole.
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Measure centre‑to‑centre: between mounting holes or handle and key cylinder.
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Measure door thickness across the door’s edge.
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Look for adjustable features in the latch.
Choosing the right hardware
Once you have your measurements, choosing hardware becomes a matter of style and function. Hardware Box offers levers, knobs, pull handles and sliding door pulls and privacy locks in a variety of finishes to help create a unified look across your home.
Final thoughts
Measuring might not be the most exciting part of a renovation, but it’s the foundation of a flawless hardware upgrade. Taking a few extra minutes to measure backset, centre‑to‑centre spacing and door thickness will save you from costly mistakes and ensure your new handles function as beautifully as they look. Whether you’re fitting a sleek modern lever or a statement pull, armed with these measurements you can shop confidently and let the style take centre stage.
