This Intake survey guidance document discusses key considerations related to the selection, assignment, and use of portion size estimation methods in a quantitative 24-hour dietary recall survey. Portion size estimation methods that are well-suited for a large-scale survey are described; guidance on how to select and assign portion size estimation methods to food items is provided; and key tasks and considerations for operationalizing the portion size estimation methods selected for use in a survey are described. The document is a must-read, key resource for those who are planning a quantitative 24-hour dietary recall survey in a low- or middle-income country context.