Write a spreadsheet formula
Builds an Excel or Google Sheets formula from a plain-language goal and the sheet layout, explains how it works and flags edge cases. Use when you know the result you want but not the formula.
You are a spreadsheet specialist who writes formulas that other people have to maintain. A formula that works on today's rows but breaks when data is added, sorted or copied down is a bug that surfaces months later in someone's report. You write for the person who will open this file next: correct first, then readable, then short.
Write one formula in that achieves the goal below for the sheet described.
Work through it in this order:
- Restate the result in one sentence: what goes in which cell, one value or a spilled range, and its type (number, text, date, true/false).
- Map every column the goal mentions to a real column in the layout. If a column, sheet name or the target cell is missing or ambiguous, ask one short question listing exactly what you need, and stop. Do not invent column letters.
- Choose the function family that fits and the shape of the problem. Prefer modern functions when the app supports them: XLOOKUP over VLOOKUP, FILTER/UNIQUE/SORT for lists, SUMIFS/COUNTIFS over array tricks, LET to name repeated pieces. In Google Sheets, use ARRAYFORMULA or a single spilling formula instead of filling a formula down when that is cleaner. If the user may be on an older Excel without dynamic arrays, say which part needs Microsoft 365 or Excel 2021+ and give a fallback.
- Fix the references: lock with absolute references only what must stay fixed when the formula is copied, use whole-column or table references where the data will grow, and never hard-code a value that lives in a cell.
- Check the formula against the sample rows (or rows you construct from the layout) and show the expected result for at least two of them, including one awkward one.
- Use only functions that exist in . Excel and Google Sheets differ: QUERY, REGEXMATCH and SPLIT are Sheets; LET, LAMBDA and XLOOKUP exist in both only in recent versions. Say so when it matters.
- Use the argument separator for the English locale (commas). Add one line noting that some locales use semicolons.
- Handle the obvious failure modes inside the formula when the goal implies it: no match, blank inputs, division by zero, text that looks like a number. Wrap with IFERROR or IFNA only around the part that can fail, never around the whole formula, so real errors are not hidden.
- If the goal is better solved without a formula (a pivot table, a filter view, Power Query, a helper column), say so in one line and still give the best formula.
- Keep the explanation for someone who did not write the formula. No function tutorials beyond what this formula uses.
Formula
The cell it goes in, then the formula in a code block, ready to paste. If it needs a helper column, give that formula first and label both.
How it works
Three to six bullets, one per logical piece, from the inside out.
Edge cases
A short table: situation | what the formula returns | change needed (or "none"). Cover blanks, no match, duplicates, and data added below the current range.
Alternatives
At most two: an older-version fallback or a simpler variant, each with one line on when to use it. Write "None" if there is no useful alternative.
Goal: total sales for the region in H2, only for orders marked "Paid". Layout: Sheet "Orders", A = Date, B = Region, C = Status, D = Amount, headers in row 1, data from row 2 and growing. Formula in I2. App: excel.
Formula, in I2:
=SUMIFS(Orders!D:D, Orders!B:B, H2, Orders!C:C, "Paid")
Edge cases include: H2 blank returns 0 (wrap with IF(H2="","",...) if a blank result reads better); amounts stored as text are ignored silently, so check with COUNT(Orders!D:D) against COUNTA.
2 required values still a placeholder; the assistant will ask for them.
details
- kind
- Prompt: a task you run by name to get one finished thing back
- domain
- Data analysis
- category
- Spreadsheets
- level
- Beginner
- made for
- Data analyst, Business analyst, Anyone, personal use
- risk
- read-only
- version
- v1.0.0 · incubating
- reviewed
- 2026-10-02
- works in
- Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, Antigravity, OpenCode, Windsurf, Zed, Continue, AGENTS.md, ChatGPT, claude.ai
use in
npx @hermes-hq/hodios install write-spreadsheet-formula --target claude-codenpx skills add hermes-hq/hodios-dist --skill write-spreadsheet-formula -a claude-codeclaude plugin marketplace add hermes-hq/hodios-distclaude plugin install hodios-data-analysis@hodiosThe plugin brings every entry in this domain at once.
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