> ## Knowledge Base Index
> Fetch the complete knowledge base index at: https://faq.lechemiseur.fr/sitemap.xml
> Use this file to discover available pages before exploring further.
> Pure-Markdown content can be obtained by appending a '.md' suffix to the content URLs listed in the sitemap (without the trailing slash).

# What is the Fit Key?  


# The Fit Key - your personal sizing profile

Your Fit Key is a unique 5-character code that stores the measurements and fit preferences of your shirt or trousers, making future reorders simple and consistent.

![Your Fit Key and personal Signature are printed inside your shirt for easy reference when reordering.](https://storage.crisp.chat/users/helpdesk/website/-/2/1/5/d/215d429d5477cc00/image_aqelky.png =501xauto)


![](https://storage.crisp.chat/users/helpdesk/website/-/2/1/5/d/215d429d5477cc00/image_18wdtw8.png)

### How to create your first Fit Key with AI?

Simply enter your height, weight and age on the website. LE CHEMISEUR® AI calculates your optimal fit using data from more than 50,000 customers. Start by choosing a [dress shirt](https://lechemiseur.fr/en/eshop/dress-shirts) and the website will guide you through the process.

### Reordering with your Fit Key

Once you have your first Fit Key, reordering becomes simple and precise.

You can find your Fit Key:

* on the back yoke inside your shirt, next to your name,
* [or in your customer account.](https://lechemiseur.fr/en/my-account#/)

If needed, you can [adjust your fit before reordering](https://faq.lechemiseur.fr/en/article/adjusting-your-fit-key-for-a-follow-up-order-1abg6bj/). For example, you can add +1 cm to the chest. 

Because your previous shirt serves as the reference, adjustments are easy and reliable.
Each updated fit generates a new Fit Key for future orders.