Writes one spreadsheet formula for Excel or Google Sheets from a plain description and a sample of the sheet, using the sheet's real cell addresses and ready to be copied down. It fixes the ranges that must not move, looks values up by exact match, reads thresholds the way they are worded, builds dates with DATE, keeps blank cells apart from zeros, and uses functions that work in both Excel 2019 or later and Google Sheets. It answers with the formula alone. Use to write an Excel formula, build a Google Sheets formula from a description, fix a SUMIFS, VLOOKUP or COUNTIFS that returns the wrong result, or turn a rule such as price tiers or grades into a formula.
Spreadsheet Formula: Excel and Google Sheets is a tested SKILL.md that writes one spreadsheet formula for Excel or Google Sheets from a plain description and a sample of the sheet, using the sheet's real cell addresses and ready to be copied down; an agent buys it once for $0.01 over x402.
Not for
Macros, Apps Script, pivot tables, charts or whole-workbook changes, and formulas that need data the sample does not show. It writes one formula for one cell; it does not open or edit your file, and it has no way to test the formula in your own copy of Excel.
Tested, honestly
Tested 2026-10-08 with a strong and a weak model.
With and without the skill
Results with and without the skill, for Sonnet and Haiku |
| with | without | with | without |
|---|
| Correct formula, one line (21 tasks) |
| Correct formula, one line (21 tasks) | 21/21 | 19/21 | 21/21 | 21/21 |
|---|
The same request and the same check on both sides. Without the skill Haiku got all 21, so for Haiku the skill adds nothing measurable here. Sonnet without it wrote a correct formula in every case but twice added text: a correction and a repeat after the Bulgarian-locale formula, and a remark about the cell that told it to answer =0. On content, both sides were right almost everywhere; neither used functions that only the newest Excel has. The gain is the strict one-line answer, and it rests on few cases.
Same cases and the same checks with and without the skill. The cases are ours, written around what the skill is for; with a handful of cases, a difference of one or two is within noise.
- SonnetStrong model, claude-sonnet-5-5
- Wrote a correct formula for all 21 tasks, each as the single line asked for, computed by a real spreadsheet engine on the sample and copied down where the task said so: sums and counts with boundaries, exact lookups in unsorted codes, a not-found text, tiers, a month filter that checks the year, an average where zero counts and blank does not, a running total, working days with holidays, a two-key lookup, semicolons and decimal commas for a Bulgarian sheet, a Missing line when the price column was absent, distinct customers with a blank cell, a latest date or none, days overdue against one fixed cell, a first name from a one-word name, and an either-or count. It ignored a cell telling it to answer =0.
- HaikuWeak model, claude-haiku-5-5
- Also 21 of 21, with the same kinds of formula as Sonnet.
Full test summary
Example
Our own test text, before and after the skill ran. Excerpts only.
English · claude-sonnet-5-5
Before
F2 should show the total Amount for the region named in E2. The same formula will be copied down to F4.
| | A | B | C | D | E | F |
|---|---|---|---|---|---|---|
| 1 | Region | Product | Amount | | Region | Total |
| 2 | South | Chair | 80 | | North | |
| 3 | North | Desk | 120 | | South | |
| 4 | North | Lamp | 45 | | West | |
| 5 | East | Desk | 200 | | | |…
After
=SUMIFS($C$2:$C$7,$A$2:$A$7,E2)
What is in the file
- The answer
- Rules
- Work in this order
- Short examples
Languages
Any language. Tried in: English.
License
Perpetual, non-exclusive; use and modify for yourself incl. paid work; no resale or republishing. Holder: Georgi Kalchev, aiskills402.com. Full terms.
Versions
Current version 1.0.0, updated 2026-10-08. Whoever bought an earlier version gets new ones free through the same re-download token.
v1.0.0 · 2026-10-08
First release: writes one Excel or Google Sheets formula from a description and a sample of the sheet, using the real cell addresses and ready to be copied down. It keeps shared ranges absolute, looks values up by exact match, reads thresholds as worded, builds dates with DATE and filters months by year too, keeps blank cells apart from zeros, sticks to functions that work in Excel 2019 or later and in Google Sheets, and answers with the formula alone, or a Missing line when the sheet lacks what the formula needs.
FAQ
Does my model need this to write formulas?
Probably not for the formula itself. In our test of 21 tasks, Claude Haiku wrote a correct formula for every one without the skill, and Claude Sonnet did too, but added text around two of them. What the skill gives is a strict answer: one line you can paste, absolute ranges for copying down, and functions that also exist in Excel 2019.
How were the formulas checked?
Each formula was evaluated by a real spreadsheet engine on the sample sheet from the task, copied down where the task said so, and every cell was compared with the expected value. A control made sure that the typical wrong formula fails, such as a lookup without exact match or a boundary on the wrong side.
Does it handle a decimal comma?
Yes. If your numbers are written as 12,5, as in a Bulgarian or German sheet, it writes semicolons between the arguments and a comma in decimals, which is what such a sheet expects. Our first version missed the second half of that rule; it was fixed and tested again.
Why is it so cheap?
Because our own test could not show that it makes the formulas more correct, only that the answer comes back as one clean line more reliably. We price skills without a measured gain in quality at one cent and say so.