The acceptable level of technical debt can vary depending on the organization and project but it is generally considered to be the amount that can be managed and controlled within the budget and resources of the company. It is also considered acceptable when it's incurred with a clear plan, understanding the trade-offs, and the costs involved and when it aligns with the organization's goals and objectives.
Measuring technical debt can be challenging, as it often involves quantifying the costs associated with maintaining and updating the codebase. One way to measure technical debt is through metrics such as number of code smells, cyclomatic complexity, or maintainability index which can provide an indication of the codebase's complexity and potential costs of maintaining it. Additionally, code reviews and software development tools can also be used to measure technical debt and identify areas that need improvement.
It's also important to consider the business perspective, by calculating the costs and benefits of the incurred technical debt in terms of additional features or time to market. Regular reviews and tracking progress over time is crucial to ensure that the technical debt is under control and aligned with the organization's goals and objectives.