--- title: "Get the perfect fit: How to measure your door for a Bold smart lock?" description: Before placing an order for your Bold Smart Lock, it's crucial to determine the right size. Bold cylinders come in standardized lengths, so let's get you measured up! --- [Skip to content](https://knowledgebase.boldsmartlock.com/en/knowledge/measuring-correctly-how-to-determine-which-bold-smart-cylinder-length-you-need#main-content) - [English](https://knowledgebase.boldsmartlock.com/en/knowledge/measuring-correctly-how-to-determine-which-bold-smart-cylinder-length-you-need) - [Deutsch](https://knowledgebase.boldsmartlock.com/de/knowledge/richtig-messen-wie-bestimmen-sie-welche-bold-smart-cylinder-länge-sie-benötigen) - [Français](https://knowledgebase.boldsmartlock.com/migration/nl/knowledge-fr/obtenez-lajustement-parfait-comment-mesurer-votre-porte-pour-le-bold-smart-lock-) - [Nederlands](https://knowledgebase.boldsmartlock.com/nl/knowledge/op-de-juiste-manier-meten-hoe-bepaal-je-welke-bold-smart-cylinder-variant-je-nodig-hebt) English Show submenu for translations [![Bold Logo - Digital - Square - White BG (5)](https://knowledgebase.boldsmartlock.com/hs-fs/hubfs/Bold%20Logo%20-%20Digital%20-%20Square%20-%20White%20BG%20(5).jpg?width=150&height=150&name=Bold%20Logo%20-%20Digital%20-%20Square%20-%20White%20BG%20(5).jpg)](https://boldsmartlock.com/) Open main navigation Close main navigation - - [English](https://knowledgebase.boldsmartlock.com/en/knowledge/measuring-correctly-how-to-determine-which-bold-smart-cylinder-length-you-need) - [Deutsch](https://knowledgebase.boldsmartlock.com/de/knowledge/richtig-messen-wie-bestimmen-sie-welche-bold-smart-cylinder-länge-sie-benötigen) - [Français](https://knowledgebase.boldsmartlock.com/migration/nl/knowledge-fr/obtenez-lajustement-parfait-comment-mesurer-votre-porte-pour-le-bold-smart-lock-) - [Nederlands](https://knowledgebase.boldsmartlock.com/nl/knowledge/op-de-juiste-manier-meten-hoe-bepaal-je-welke-bold-smart-cylinder-variant-je-nodig-hebt) English Show submenu for translations - [Contact us](https://boldsmartlock.com/contact) [Contact us](https://boldsmartlock.com/contact) Welcome to Bold, how can we help you? - There are no suggestions because the search field is empty. 1. [Support Centre](https://knowledgebase.boldsmartlock.com/en/knowledge?hsLang=en) 2. [New to Bold](https://knowledgebase.boldsmartlock.com/en/knowledge/new-to-bold?hsLang=en) 3. [Is my door Bold ready?](https://knowledgebase.boldsmartlock.com/en/knowledge/new-to-bold?hsLang=en#is-my-door-bold-ready) # Get the perfect fit: How to measure your door for a Bold smart lock? ## Before ordering your Bold smart lock, it is essential to confirm your door's measurements. Bold smart locks come in standardised sizes (with adjustable components), so measuring correctly helps you select the right fit. Use the sizing configurator below, or follow our step-by-step instructions to get the perfect fit. [Use the sizing configurator](https://boldsmartlock.com/sizing-configurator) [![Sizing configurator EN](https://knowledgebase.boldsmartlock.com/hs-fs/hubfs/Sizing%20configurator%20EN.png?width=670&height=377&name=Sizing%20configurator%20EN.png)](https://boldsmartlock.com/sizing-configurator)   #### Step-by-step measuring guide First, make sure your door has an Euro Profile Cylinder. ![Euro profile EN](https://knowledgebase.boldsmartlock.com/hs-fs/hubfs/Euro%20profile%20EN.webp?width=300&height=300&name=Euro%20profile%20EN.webp) To get started, you will need a measuring tape or a ruler. 1. **Find the centre screw hole** of your current lock, this is your reference point. 2. **Measure from the centre screw hole to the outer edge of your door including any metal plating.**(on the interior side). 3. Repeat the process **on the exterior side**: from the centre screw hole to the outer door edge. 4. Be sure to **include any existing hardware or security features** like core pull protection in your measurement. These may impact the total lock length required. ![Outdoor size EN](https://knowledgebase.boldsmartlock.com/hs-fs/hubfs/Outdoor%20size%20EN.webp?width=300&height=300&name=Outdoor%20size%20EN.webp)![Indoor size EN](https://knowledgebase.boldsmartlock.com/hs-fs/hubfs/Indoor%20size%20EN.webp?width=300&height=300&name=Indoor%20size%20EN.webp)   #### Adjustable outer length Bold Smart Locks feature an **adjustable outside module** to accommodate different door thicknesses. - Standard outside lengths: **30 mm or 50 mm** - Extension options: **+5 mm, +10 mm, or +15 mm** - Example: The SX33 version can extend from 30 mm to 35, 40, or 45 mm using the included adapters. #### Key considerations - **Mind the margin**: Ensure at least **30 mm of space** between the lock’s centre hole and the door frame on the inside. This prevents the thicker inside knob (47 mm wide and 39.5 mm deep) from being blocked or pinched. - **Sliding doors**: The depth of the inside knob may limit movement. If your door slides open internally, double-check that this 39.5 mm depth allows for smooth operation. ![min 3 cm EN](https://knowledgebase.boldsmartlock.com/hs-fs/hubfs/min%203%20cm%20EN.webp?width=300&height=300&name=min%203%20cm%20EN.webp) #### Understanding the Bold Smart Lock’s dimensions - **Outside knob** diameter: 32 mm - **Outside knob** depth: 32.6 mm - **Inside knob** diameter: 47 mm - **Inside knob** depth: 39.5 mm > This means: The inside knob is thicker and extends further than the outside knob. Make sure your door has enough clearance, especially on the interior side. 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