The phrasal verb "add in" is commonly used in informal speech and writing, though it occasionally appears in formal contexts, particularly in instructions or guidelines that involve combining elements. It means to include or incorporate an additional component into an existing set or mixture. General usage patterns show that it frequently appears in cooking ("Add in the spices"), software development ("Add in more features"), or any situation requiring enhancements or modifications. The context typically involves an element being added to complete or improve the whole. While it often conveys a straightforward action of inclusion, its usage is generally understood through the context of the task or process being described.
B1
PreIntermediate
1. To include something as an additional element.
Make sure you add in the costs of materials when calculating the project total.
She decided to add in a few extra credit questions for the students.
2. To incorporate something into a whole or mix.
Don't forget to add in the new figures in the report.
They always like to add in some interesting facts during their presentation.