The user scans his/her foot with a mobile phone. This is technically performed with the help of a the Depth-, ToF- or Lidar sensor built in smartphones as well as some fancy AI to detect the foot in 3D in space. This makes spotsize‘s uniqueness with the biometric 3D-Scan – a Digitial Twin of a human foot just with a mobile phone. As no other vendor spotsize® allows consumers to playfully obtain a scan of his/her foot with AR features. The 3D- Digital Twin is the exact representation of the foot scanned. With the Digital Twin now the system can measure exactly the feet and compare with all available shoe data. The algorithm calculates the best fit by matching the dimensions of the real foot with the thousands of real product data (from the shop). To find the right size the Digital Twin is matched in real time. In just a few seconds with no need to enter any data and wait for any further instructions or email notifications the user gets his/her size recommendation. All seamlessly integrated in one place – the online shop.