Editor's pick
The variable syntax is brilliant. Changing tax rate from 0.08 to 0.10 instantly updated 500+ formulas. Makes spreadsheets maintainable and formulas self-documenting. Perfect for financial modeling.
Namrit Sheth
Data Analyst
Excel Assistant
Excel AI assistant & Copilot for everyday formula work.
Write, explain, and debug formulas in plain English — then keep the ones that work as reusable snippets in a proper editor. It's a productivity workspace for the formula bar, not a chat box you copy out of.
Add to Excel
Free plan — no credit card, installs in about 30 seconds.
Loading the editor…
Free, runs in your browser — no signup. Inserting into your real sheet, AI, and sync go live the moment you add it to Excel.
AI for Excel formulas: write, explain, debug
Three jobs, one side panel.
Describe what you need
Ask for the calculation in plain English from the side panel next to your workbook. The assistant sees the formula open in the editor when you ask, so a follow-up like "now exclude refunds" edits that formula instead of starting over.
Get the formula and a line-by-line explanation
The formula comes back with an explanation of each part, so you can check that it does what you meant before it touches a cell. Keep editing it by hand in the same editor.
Paste a broken formula, get the likely cause
When a formula returns #VALUE!, #N/A or simply the wrong number, paste it in and choose Fix Error. The assistant points at the probable cause and proposes a corrected formula you can review first.
Excel AI assistant, inside the sheet
Your spreadsheet experience, reimagined.
Excel AI examples
Generate, explain, debug: five real exchanges.
You ask
How many different customers are in column A? Ignore empty rows.
Formula
=COUNTA(UNIQUE(FILTER(A2:A1000, A2:A1000<>"")))FILTER removes blanks before UNIQUE, otherwise an empty cell counts as one extra customer. Needs Microsoft 365.
You paste
=INDEX(B:B, MATCH(MAX(C:C), C:C, 0))Assistant
Finds the largest number in column C, works out which row it is on, and returns the value from column B on that same row. In a sales list, that is the name of the top seller.
Explain is most useful on formulas someone else wrote. The assistant describes intent, not just the function names.
You paste
=C2*D2 → #VALUE!Assistant
#VALUE! because C2 holds text, not a number. It looks like 12 but was pasted with a trailing space. Use =VALUE(TRIM(C2))*D2, or clean the source column once.
Numbers stored as text are the most common cause of #VALUE! in imported data.
You paste
=VLOOKUP(A2, Prices!A:B, 2) → wrong pricesAssistant
The fourth argument is missing, so VLOOKUP does an approximate match and needs Prices sorted by column A. It is not, so you get a neighbouring row's price. Add FALSE for an exact match: =VLOOKUP(A2, Prices!A:B, 2, FALSE).
No error is shown here, which is why this bug survives for months. The explanation catches it.
You ask
Working days between the order date in B2 and the ship date in C2
Formula
=NETWORKDAYS(B2, C2)NETWORKDAYS counts both the start and end day and skips weekends. Add a holiday range as a third argument to skip those too.
Excel AI assistant vs Copilot in Excel
Two assistants, different jobs.
Copilot in Excel is Microsoft's assistant for the whole of Office. It works across Word, Outlook, PowerPoint and Excel, and you get it through a Microsoft 365 Copilot license. In Excel it can analyze tables, suggest charts and write formulas.
Formula Foundry is an add-in focused on formulas only: an editor you can read, an assistant that writes, explains and fixes formulas, and a snippet library that keeps what works. It has a free plan, it runs in Google Sheets as well as Excel, and it works alongside Copilot if you already have it.
Formula Foundry reviews
What our users say
Formula Foundry is genuinely impressive. Simplifying complex formulas, adding variables, snippets, and multi-tab editing inside Sheets is such a game-changer. As someone who has to deal with sheets, dashboards and pipelines every day, this feels like a tool built exactly for the pain points data people deal with.
Pavan Kishore Chaparla
Data Analyst
Variables and vlookup are extremely useful in transferring Excel skills and keeping a sheet clean, as well as processing in fewer steps than I otherwise would have known how.
Jason Tau
Senior Financial Planning Analyst
I found the AI Assistant extremely helpful because it saved me time by generating formulas automatically and suggested improvements I might not have thought of. It made complex tasks much easier and more intuitive, especially for repetitive or complicated formulas.
Anand Kumar Gade
Financial & Reporting Analyst
As a marketer, I always end up back in spreadsheets — forecasting, funnel math, quick models, etc. I'm thrilled Formula Foundry created a productivity tool that actually makes a difference with my critical spreadsheet work.
Megan Wells
Vice President Marketing
My favorite feature is the editor and being able to more easily structure my formulas. The easy readability is a game changer! Also, the variables are super useful when I need to put together a complex report.
Brian Norman
Sales Engineer
Free plan pricing
Start free. Upgrade when it pays for itself.
Free
$0
Free forever
Everything you need to get started — no card required.
Get started freePro
$7/ month
billed annually, or $9 / month billed monthly
Unlimited tabs, snippets, and variables for power users.
Upgrade to ProBusiness
$12/ seat / month
billed annually, or $15 / seat / month billed monthly
Shared snippets, seats, and team management.
Upgrade to Business
Enterprise. Everything in Business, plus single sign-on (SAML or OIDC), admin controls, custom onboarding & training, dedicated support, and an SLA — tailored to your organization with volume pricing.
Talk to salesAdd to Excel or Google Sheets
You're one step away from better formula work.
Add Formula Foundry to Excel and let it write, explain, and remember your formulas — in about 30 seconds, with no credit card.
Add to Excel
Free plan — no credit card, installs in about 30 seconds.
Excel AI assistant FAQ
Excel AI Assistant FAQ
- It writes formulas from plain-English descriptions, explains formulas you don't understand, and suggests fixes when one errors out. Around that it gives you a real editor, a visual builder, reusable variables, and a snippet library — so it's an everyday workspace, not a one-off helper. See how the Excel formula explainer works.
- Formula Foundry is focused on formulas specifically and works across both Excel and Google Sheets. Beyond generating formulas it lets you save and reuse them as snippets, manage shared variables, and translate formulas between the two apps — the things that make formula work repeatable, not just faster once.
- Yes — there's a free plan with no credit card required, plus a free in-browser playground you can use without installing anything. Paid plans add higher AI limits and team snippet sharing.
- Yes. It installs as an add-in from the Microsoft Marketplace and runs in a side panel right next to your spreadsheet. The same workspace is also available for Google Sheets.
- The editor runs inside Excel or Google Sheets. The AI assistant is opt-in: when you ask, it sees the formula, your sheet's header row and your @@variables, not the rows of data. We only store your account details and any snippets you save, and you can remove them at any time.