Google Sheets Formula Builder

Use this skill when the formula itself is the task.

Read ./references/formula-patterns.md before drafting the first formula. The point is not to relearn Sheets from scratch. It is to refresh exact syntax and a few high-value function constraints before writing.

Workflow

1. Ground the formula in the live sheet first: exact input columns, target output cell or column, and a few representative rows.
2. Choose the formula shape deliberately:
   • row formula when the logic is local to one row and should copy down
   • spill formula when one formula should populate a whole output range
   • lookup formula when the task is key-to-value retrieval
   • filter/query formula when the task is to derive a subset or summary table
   • named function only when the same logic is conceptually reusable
3. Draft the formula in one helper cell or a scratch location first.
4. Test on a small representative slice, including likely edge cases.
5. Iterate until the sample output is correct, then roll the formula out to the intended target range.

Output Conventions