Shrink oversized .xlsx files by compressing the images inside them. Your formulas, values and formatting are never touched.
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Most oversized .xlsx files are large because of embedded images - pasted screenshots, logos or scanned pages - stored at far higher resolution than needed. This tool opens your workbook entirely inside your browser, finds those embedded images, recompresses them, and repacks the file. Your cell values, formulas, charts, pivot tables and formatting are left exactly as they are; only image data and the file packaging are touched.
Yes. The compressor never reads or modifies cell values, formulas or calculation results. It only recompresses image files inside the workbook package. No cells, formulas, or calculation results are ever modified.
No. The entire process, from reading your file to generating the compressed download, runs locally in your browser using JavaScript. Your spreadsheet is never sent to any server.
If your file is large mainly due to sheer amount of data or a big pivot cache rather than images, compressing images alone won't help much - this tool is specifically built for image-heavy workbooks such as ones with pasted screenshots, scanned receipts or logos.
An .xlsx file that will not attach to an email is almost never large because of its numbers. A worksheet with fifty thousand rows of figures and formulas typically occupies a few megabytes at most. When a workbook reaches 30, 60 or 150 MB, the cause is nearly always media: product photographs, screenshots, scanned signatures and logos pasted straight from a camera or phone at full resolution.
The reason is that Excel stores what you gave it. When you display a 12-megapixel photograph in a cell-sized frame, Excel shrinks the image on screen and keeps the original file intact inside the workbook. Fifty product photos at 4 MB each is 200 MB of payload sitting behind a sheet that looks like a simple catalogue.
This is the detail that makes the whole problem tractable. Since the 2007 format, an .xlsx file is a ZIP archive containing a structured folder of XML documents plus a media folder holding the images. You can see this yourself: take a copy of the file, rename the extension from .xlsx to .zip, and open it. Inside you will find a folder called xl, and within it media. Compare the size of that media folder against the size of the whole archive and you will know immediately whether images are your problem.
That structure is what this tool works with. It opens the archive in your browser, re-encodes the images inside xl/media at a sensible quality and resolution for on-screen and printed use, and rebuilds the archive with every other part byte-for-byte unchanged.
| Left completely untouched | Modified |
|---|---|
| Formulas, named ranges and references | Embedded raster images in xl/media |
| Cell values, data types and precision | |
| Number formats, styles and conditional formatting | |
| Sheet order, names, freeze panes and print areas | |
| Charts, pivot tables and their sources | |
| Macros in .xlsm files and defined VBA |
Because the compression applies only to image data, the numerical content of your workbook cannot be altered by it. That is a deliberate design decision: the failure mode of a tool that touched formulas would be silent and catastrophic, whereas the failure mode of over-compressed images is visible immediately.
If the media folder turns out to be small and the file is still huge, one of these is usually responsible. None of them are fixed by image compression, but all of them are fixable.
Press Ctrl+End on each sheet. If it jumps to row 900,000 or column XFD when your data ends at row 400, Excel is storing formatting for hundreds of thousands of empty cells. Select all rows below your data, delete the entire rows, do the same for columns to the right, then save and reopen. This alone routinely removes tens of megabytes.
Selecting column headers and applying fills, borders or number formats writes style information across the entire column. Apply formatting to the range you actually use, or convert the range to a proper Excel Table so formatting follows the data.
A pivot table keeps its own hidden copy of the source data. Several pivots over the same source can multiply that copy. In PivotTable Options, disabling "Save source data with file" and enabling "Refresh data when opening the file" removes the cached duplicate.
Rules copied and pasted repeatedly can fragment into thousands of near-identical entries covering overlapping ranges. Open the Conditional Formatting Rules Manager, check the count, and consolidate.
Workbooks that have travelled between many users accumulate thousands of unused cell styles and broken defined names, often visible as errors in the Name Manager. Clearing them helps.
xl/media dominates, compress the images. If a single sheet XML dominates, you are looking at a used-range or formatting problem instead.Saving as .xlsb, the binary workbook format, typically produces a considerably smaller and faster-opening file with identical content, and it supports macros. The trade-off is that some external tools and older integrations read it less readily than .xlsx, so it suits internal working files better than files you send outward.
For genuinely large datasets, consider whether the raw data needs to travel at all. Linking to a shared source, or sending a summary sheet rather than the full extract, solves the underlying problem rather than compressing it. And if the images are for reference rather than presentation, hyperlinking to them instead of embedding removes the payload entirely.
Results depend entirely on what your images looked like going in. A workbook full of untouched phone photographs commonly drops by 70 to 90 per cent. One containing screenshots already saved as compact PNGs may barely change, because there is little redundancy left to remove. Vector graphics and charts are not raster images and are not affected. If a file does not shrink meaningfully, that is useful information: it means your size is coming from something in the previous section.
Always keep the original until you have opened the compressed copy and checked the images at the zoom level they will actually be viewed at. Compression is lossy by nature, and only you can judge whether the result is acceptable for your document.
Spreadsheets are among the most sensitive documents an organisation has, routinely holding pricing, payroll, customer lists and unpublished financials. Uploading one to an unknown web service to save a few megabytes is a poor trade, so this tool does not ask you to. Your workbook is read by your browser using the File API, unzipped in memory on your machine, re-encoded there, and offered back to you as a download. There is no upload step, no server-side processing, no temporary copy on someone else's disk and no retention period to worry about. You can load this page, disconnect from the internet entirely, and compress a file successfully, which is the clearest possible demonstration that nothing is being transmitted.
In most cases the cause is embedded images stored at full camera resolution rather than the data itself. Rename a copy of the file to .zip, open it, and look at the xl/media folder. If it dominates the archive, images are the problem. If it does not, the usual culprits are an inflated used range, whole-column formatting, stale pivot caches or excessive conditional formatting rules.
No. This tool only re-encodes the raster images inside the xl/media folder. Formulas, cell values, number formats, styles, conditional formatting, charts, pivot tables, sheet structure and macros are all rebuilt byte-for-byte unchanged.
It depends on what the images were. Workbooks containing unedited phone or camera photographs commonly shrink by 70 to 90 per cent. Files whose images are already compact PNG screenshots may barely change, because there is little redundancy left to remove.
Press Ctrl+End on each sheet. If it jumps far beyond your actual data, Excel is storing formatting for empty cells; delete the entire unused rows and columns, then save and reopen. Also check for whole-column formatting, pivot tables saving their source data, and thousands of fragmented conditional formatting rules.
The binary .xlsb format usually produces a noticeably smaller and faster-opening file with identical content, and it supports macros. The trade-off is weaker compatibility with some external tools and integrations, so it suits internal working files better than files you send to others.
No. The file is read by your browser, unzipped in memory on your own machine, re-encoded locally and handed back as a download. There is no upload, no server-side processing and no copy retained anywhere. You can disconnect from the internet after the page loads and it will still work.