What the XLSX Formula Inspector does
This inspector lists every formula in an Excel workbook by sheet and cell, with the value Excel last calculated, and audits them: cells holding errors such as #DIV/0!, formulas that break the pattern of their neighbours, references to other workbooks, volatile functions like NOW, RAND and INDIRECT, and numbers typed directly into formulas instead of kept in input cells.
It reads the .xlsx file's XML directly, so nothing is calculated, no macro is opened and no link is refreshed - you see the workbook exactly as it was saved. It is the quick review to do before you trust, share or inherit a spreadsheet model, and it runs in your browser without uploading the file.
How to use it
- Drop an .xlsx or .xlsm file, or load the example.
- Read the findings first: errors and inconsistent formulas are the likeliest real mistakes; external links, volatile functions and hard-coded numbers are risks worth a look.
- Use the formula table to find a cell - it is sortable and filterable by sheet, cell, formula text or finding.
- Download the list as CSV (with each formula's R1C1 signature) or the whole audit as JSON for a review record.
Reading the results
Differs from neighbours compares each formula's relative (R1C1) form with the cells either side of it in its row and column. When the two neighbours agree with each other and this cell does not, it is flagged - the same idea as Excel's inconsistent-formula warning. A deliberate exception (a total row, a one-off adjustment) is also flagged, so read it as "check this", not "wrong".
Hard-coded numbers are numeric constants other than 0 and 1 inside a formula, such as =B2*0.38. They are not errors, but a rate or threshold buried in formulas is easy to update in one place and forget in another.
Volatile functions recalculate whenever anything in the workbook changes. In big models they slow everything down, and RAND or NOW make the file's results change every time it is opened.
Worked example: a quarterly budget with four planted problems
The example workbook has 35 formulas: 12 shared =E2*F2 totals on Sales and 23 on Budget 2025. Sales is clean - a shared formula filled down has the same R1C1 form, R[0]C[-2]*R[0]C[-1], in every row.
On Budget 2025, cost of sales is =B2*0.38, =C2*0.38 and =E2*0.38 in Q1, Q2 and Q4, but =D2*0.4 in Q3. Relative to their own columns, C3 and E3 both read R[-1]C[0]*0.38, while D3 reads R[-1]C[0]*0.4, so D3 is flagged as differing from its neighbours - and all four are flagged for the hard-coded rate.
E7 divides Q4 revenue by a headcount of 0 and holds #DIV/0!. B8 reads [1]Rates!$B$2 from an external file on S:, B9 uses NOW() and B10 uses INDIRECT and RAND, so the workbook's results depend on a file you may not have and change every time it recalculates.
Limitations: what the result does not prove
- Values are the ones cached at the last save. If a workbook was written by a program that did not calculate, the cached values are missing and the table says so.
- The inconsistency check looks at immediate neighbours in rows and columns. It does not trace precedents or understand what a model is meant to do, and it cannot find a formula that is consistently wrong.
- Only .xlsx and .xlsm are read; .xls, .xlsb and .ods are not. Encrypted (password-protected) workbooks cannot be opened.
- Formulas inside charts, conditional formatting, data validation and pivot caches are not listed - only cell formulas and defined names.
Privacy: where your data goes
Everything you paste, type or drop is processed in this browser tab. It is not uploaded, logged, stored or sent to analytics. Session recording and tag-manager scripts are switched off on this page.
Standards and sources
- ECMA-376 Office Open XML File Formats - checked 19 Sep 2026
- Microsoft - Excel recalculation and volatile functions
- Microsoft - Detect errors in formulas
- European Spreadsheet Risks Interest Group (EuSpRIG) - research on spreadsheet errors
Frequently asked questions
How can I list all formulas in an Excel workbook?
Drop the workbook here and every cell formula appears in one table with its sheet, cell address and cached result, sortable and filterable, and downloadable as CSV. In Excel itself you would need Show Formulas sheet by sheet or Go To Special on each sheet.
How do I find external links in an Excel file?
The inspector reads the workbook's external link parts, lists the linked files by path, and flags every formula that uses a reference such as [1]Rates!B2. Excel's Edit Links dialog shows the files but not which cells use them.
What makes a formula inconsistent?
Written in relative R1C1 form, a formula copied across a row or down a column is identical in every cell. If a cell's R1C1 form differs from both neighbours while they match each other, something was typed over or edited in only one place, which is a common source of spreadsheet errors.
Which Excel functions are volatile?
The ones this tool flags are NOW, TODAY, RAND, RANDBETWEEN, RANDARRAY, OFFSET, INDIRECT, INFO and CELL. Microsoft documents these as recalculating on every change, not only when their inputs change, which can make large workbooks slow.
Does it run the macros or formulas in my file?
No. It unzips the file and reads the XML text of each sheet. Formulas are tokenized as text, VBA projects are only detected, and no calculation engine exists on this page, so nothing in the workbook can execute.
Why does a formula show a value but no problems when I know it is wrong?
The checks are structural: errors, broken patterns, links, volatility and constants. A formula that points at the wrong range consistently, or uses the wrong rate everywhere, passes every one of them. A review still needs someone who knows what the model should do.
Last reviewed by the A2Z.Tools team against the sources listed above.
