The number of miles required to upgrade on Lufthansa depends on several factors, including the route, class of service, and availability. Lufthansa operates a frequent flyer program called Miles & More, and the miles needed for an upgrade can vary based on your membership tier within this program. Generally, upgrading to a higher class of service, such as from Economy to Business or Business to First, will require a certain amount of additional Lufthansa Upgrade with Miles.
Lufthansa may also offer the option to bid for an upgrade through their bidding system, allowing passengers to propose an amount they are willing to pay for the upgrade using cash or a combination of cash and miles. For specific information on the miles required for an upgrade on your particular route or flight, it is recommended to check Lufthansa's official website or contact their customer service for the most accurate and up-to-date details.