Budgeting for projects can be approached using different methods depending on the project’s needs and constraints. The bottom-up method involves estimating individual tasks and summing them to form a total project budget. The top-down method starts with a total budget figure and allocates amounts to various parts of the project. A combination of both methods can also be used to leverage the advantages of each, providing a more balanced and accurate budget. These methods are well-documented in project management literature and are part of the Professional in Project Management (PPM) body of knowledge.

References: The information about these budgeting methods is supported by resources on project budget management and is consistent with the principles outlined in the PPM guide1234.