What's the typical cost comparison between lift-and-shift vs complete rewrite for mainframe modernization?

When businesses discuss mainframe modernization, the conversation quickly becomes chaotic in terms of costs. The dilemma of modernization can be summarized in a single statement: lift and shift and complete rewrite (which are synonymous with terms such as rehost, rebuild, and reimagine) do not represent conflicting alternatives. Instead, they serve different purposes with different levels of risk and quite different price points. Rehosting (also called lift-and-shift) refers to moving an application to a new environment with almost no modifications made to its source code. AWS states that 'rehosting' means moving an on-premise application to the cloud in its current form, and the transition will require minimum time and effort as no code or architectural changes are required. In addition, Microsoft considers the 'rehost' approach to modernization as being the least complex and least expensive of all modernization options. On the other hand, a complete rewrite (usually referred to as 'r