How to analyze and reduce excel workbook size before sharepoint or teams upload
- Step 1Download the workbook from SharePoint or Teams — Open the file in SharePoint/Teams, choose Download, and save a local copy. Keep the original until you've verified the slimmed-down version uploads and opens correctly.
- Step 2Run the Weight Analyzer on the local copy — Drop the
.xlsx/.xlsmin. JSZip unzips it locally — no data goes to JAD. The report ranks the internal components and names the biggest files. - Step 3Read the top category — Whatever leads the By category block is your target:
embedded_media(compress images),worksheet_data(conditional formatting / ghost rows),shared_strings(unique text),vba_macro(strip macros),external_links(audit links). - Step 4Apply the matching cleanup — Compress images in Excel; strip macros with the VBA Macro Stripper; purge notes with the Comment & Note Purger; review links with the External Link Auditor.
- Step 5Re-run to confirm the size dropped — Save the cleaned file and re-upload to the analyzer. The header's compressed total is your before/after scoreboard; aim well under the size that made Excel Online sluggish.
- Step 6Upload the lean version and remove the old one — Push the optimised file to SharePoint/Teams. Delete or version-replace the bloated original so collaborators stop opening the heavy copy.
Bloat category to cleanup action — the pre-upload checklist
Read the analyzer's top category, then take the matching action. The analyzer diagnoses; these tools/steps do the fix. Re-run after each to measure progress.
| Top category in report | Likely cause | Fix before upload |
|---|---|---|
embedded_media | Full-resolution images in xl/media/ | Excel -> Compress Pictures (96/150 ppi) + delete cropped areas |
worksheet_data | Whole-column conditional formatting / ghost rows | Manage Rules; Ctrl+End then delete empty rows; Clear Formats |
shared_strings | Many unique text values / text-IDs | Convert numeric text to numbers; archive verbose text |
vba_macro | VBA project (vbaProject.bin) | VBA Macro Stripper; save as .xlsx |
styles | Thousands of distinct cell formats | Standardise formatting; copy data to a fresh workbook |
external_links | Links to other workbooks | External Link Auditor; break stale links |
document_properties / comments | Notes, metadata | Comment & Note Purger |
Why size matters for Excel Online and Teams collaboration
General guidance for M365 collaboration. SharePoint stores large files, but Excel Online's responsiveness drops as the workbook grows — the analyzer helps you trim before that bites.
| Concern | Impact of a bloated workbook | What the analyzer helps with |
|---|---|---|
| Excel Online open time | Large/complex files load slowly or open only in desktop | Identify and cut the dominant component |
| Co-authoring sync | More data to sync = slower saves, conflict risk | Reduce decompressed size driving in-memory load |
| Upload time | Big files take longer to push over the network | Shrink the on-disk (compressed) total first |
| Version bloat | Each saved version stores the full file | Slim the file so version history stays manageable |
| Mobile / browser viewing | Heavy files may not render fully on the web | Trim media and formatting that block web rendering |
Tier limits for the Excel family (real numbers)
The analyzer runs entirely in your browser, but the upload size and row caps are enforced by tier. Weight Analyzer itself requires at least Pro.
| Tier | Max file size | Row cap | Files at once |
|---|---|---|---|
| Free | 5 MB | 10,000 rows | 1 (and Weight Analyzer is gated to Pro+) |
| Pro | 50 MB | 100,000 rows | 5 |
| Pro-media | 200 MB | 500,000 rows | 20 |
| Developer | 500 MB | unlimited rows | unlimited |
Cookbook
Real Weight Analyzer reports for files headed to SharePoint/Teams. Sizes are decompressed KB unless the line says compressed. The header's compressed number is what SharePoint will show; the decompressed number is what slows Excel Online.
A 'small' SharePoint file that crawls in Excel Online
SharePoint listed it at 7 MB and IT shrugged. But it decompressed to 44 MB of worksheet XML — exactly what makes Excel Online sluggish. The analyzer exposes the gap SharePoint hides.
Total workbook size: 7168.0 KB (compressed), 45056.0 KB (decompressed) By category: worksheet_data 42000.0 KB (93%) shared_strings 2048.0 KB (5%) styles 900.0 KB (2%) Reading: 7 MB on disk but 44 MB live -> Excel Online loads slowly. Fix the sheet XML (conditional formatting) BEFORE re-uploading.
Macro file blocked from web features
An .xlsm wouldn't run cleanly in Excel Online (macros don't execute on the web) and was heavy from an inherited VBA library. Strip macros and save as .xlsx for smoother collaboration.
Total workbook size: 9216.0 KB (compressed), 16384.0 KB (decompressed) By category: vba_macro 6144.0 KB (38%) worksheet_data 7168.0 KB (44%) shared_strings 2048.0 KB (13%) styles 824.0 KB (5%) Fix: VBA Macro Stripper -> save as .xlsx. Removes vbaProject.bin AND makes the file fully usable in Excel Online co-authoring.
Image-heavy report trimmed before Teams share
A 41 MB report with pasted screenshots. Teams uploaded it, but it opened only in desktop. Compress images and the file becomes web-friendly.
BEFORE Total workbook size: 41984.0 KB (compressed) embedded_media 39000.0 KB (93%) AFTER (Compress Pictures 96 ppi + delete cropped areas) Total workbook size: 3072.0 KB (compressed) worksheet_data 5120.0 KB (61%) embedded_media 1536.0 KB (18%) Net: 41 MB -> 3 MB; now opens instantly in Excel Online.
External links that break in the cloud
The workbook linked to a colleague's local file. Those links break once in SharePoint and prompt 'Update Links' for everyone. The analyzer flags external_links; the External Link Auditor finds them.
Total workbook size: 3072.0 KB (compressed), 8192.0 KB (decompressed) By category: worksheet_data 5120.0 KB (63%) external_links 2048.0 KB (25%) <- links to other files shared_strings 1024.0 KB (12%) Fix: run the External Link Auditor to list the links; break or repoint stale ones before uploading so collaborators don't see 'Update Links' prompts.
Pre-upload checklist run, top to bottom
A combined cleanup pass: compress images, strip macros, tighten formatting. The header line is the receipt before pushing to SharePoint.
BEFORE upload Total workbook size: 58368.0 KB (compressed), 62000.0 KB (decompressed) embedded_media 44000.0 KB (71%) vba_macro 6144.0 KB (10%) worksheet_data 10000.0 KB (16%) AFTER cleanup (images + macros + rule cleanup) Total workbook size: 4096.0 KB (compressed), 9000.0 KB (decompressed) Ready for SharePoint: 58 MB -> 4 MB, opens in Excel Online, co-authors without lag.
Edge cases and what actually happens
SharePoint shows a small size but Excel Online is slow
ExpectedSharePoint reports the compressed on-disk size; Excel Online's slowness tracks the decompressed in-memory size. The analyzer's header shows both, so a 7 MB file that decompresses to 44 MB explains the lag SharePoint's size number can't.
Macros don't run in Excel Online
Web limitationVBA macros don't execute in Excel for the web, so an .xlsm carries dead weight there. If vba_macro shows up, strip it with the VBA Macro Stripper and save as .xlsx for a smaller, fully web-compatible file.
External links break after upload
AvoidableLinks to local or moved files break in SharePoint and trigger 'Update Links' prompts for collaborators. The analyzer flags external_links; use the External Link Auditor to list and break/repoint them before uploading.
SharePoint doesn't compress the file for you
By designSharePoint stores the .xlsx as uploaded — it doesn't re-compress contents (the XLSX is already a ZIP). External zipping adds almost nothing. The real lever is reducing internal components, which the analyzer pinpoints.
File over the tier upload cap for the analyzer
Rejected (size limit)To analyse before upload you still need to fit the analyzer's tier cap: 50 MB on Pro, 200 MB on Pro-media, 500 MB on Developer. A 300 MB workbook needs Developer (or Pro-media if under 200 MB) to be diagnosed at all.
Co-authoring conflicts on a large file
Performance riskBigger files mean more data to sync, raising save latency and conflict odds during simultaneous editing. Trimming the dominant component (per the analyzer) reduces the sync payload and smooths co-authoring.
Analyzer diagnoses but doesn't fix
By design (read-only)The analyzer is a report (outputType: report); it never modifies or downloads a file. Apply the fix in Excel or with a sibling tool, then re-run to confirm before uploading the lean version.
Encrypted workbook from SharePoint IRM
Cannot read (encrypted)If the file carries encryption (IRM/sensitivity-label protection or an open-password), it's an OLE/CFB container, not a plain ZIP, and JSZip can't open it. Remove protection on a local copy first, then analyse.
Comments/threaded notes bulk up the file
AvoidableMany cell comments and threaded notes add to the workbook. Where they're surplus, the Comment & Note Purger removes them. The analyzer surfaces the related weight so you know whether it's worth purging.
.xlsb saved to reduce size
Trade-offSaving as .xlsb (binary) shrinks files and speeds desktop open, but Excel Online support for .xlsb is more limited and the analyzer's per-category breakdown is far less useful (data lands in other). For cloud co-authoring, prefer a trimmed .xlsx.
Frequently asked questions
Why is my Excel file slow in SharePoint / Teams even though it uploaded?
Upload size (compressed) and runtime performance (decompressed, in-memory) are different. Excel Online struggles with the decompressed size and complexity. The analyzer's header shows both numbers, so you can see why a 'small' file still lags.
What's the optimal Excel file size for SharePoint co-authoring?
Smaller is smoother — files in the low single-digit megabytes open and co-author best in Excel Online, while large/complex workbooks slow sync and may open only in desktop. Use the analyzer to cut the dominant component and get well under your problem threshold.
Does SharePoint compress Excel files automatically?
No. SharePoint stores the file as uploaded. An .xlsx is already a ZIP internally, so zipping it externally barely helps. The effective fix is reducing internal components — images, formatting, macros — which the analyzer pinpoints.
How do I know what's making my file big before uploading?
Download a local copy and run the Weight Analyzer. It ranks the eleven internal categories by decompressed size and names the ten biggest files, so you know whether to compress images, fix formatting, or strip macros — then re-run to confirm.
Why won't my .xlsm work properly in Excel Online?
Macros don't run in Excel for the web. An .xlsm also carries the vbaProject.bin weight. If you don't need the macros for cloud use, strip them with the VBA Macro Stripper and save as .xlsx — smaller and fully web-compatible.
My collaborators get 'Update Links' prompts — why?
The workbook links to external files (often local paths) that don't resolve in SharePoint. The analyzer flags external_links; use the External Link Auditor to find them and break or repoint stale links before uploading.
Is my data uploaded to JAD when I analyse before SharePoint?
No. JSZip unzips and measures the file in your browser. Internal financial, HR, or planning data never reaches JAD during analysis — you only see size figures on-screen, then upload the cleaned file to your own M365 tenant.
What tier do I need to analyse a large pre-upload file?
Weight Analyzer needs Pro or above. The upload cap is 50 MB on Pro, 200 MB on Pro-media, and 500 MB on Developer — choose the tier that fits the bloated workbook you need to diagnose.
Will the analyzer shrink the file for me before I upload?
No — it's diagnostic only (outputType: report). It tells you exactly what to fix; you compress/strip/clean in Excel or with a sibling tool, then re-run to verify before uploading the lean version.
Should I save as .xlsb to make it smaller for Teams?
.xlsb shrinks files and speeds desktop open, but Excel Online support is more limited and the analyzer can't break down a .xlsb cleanly (most weight shows as other). For cloud co-authoring, a trimmed .xlsx is usually the better choice.
Does the file need to be online to analyse it?
No. Download a local copy from SharePoint/Teams and analyse it locally; the analysis happens in your browser. Then upload the optimised version back to your tenant and remove the bloated original.
After cleanup, how do I prove the file is leaner?
Re-run the analyzer on the saved file. The header's compressed total is the before/after scoreboard, and the category percentages confirm the dominant component shrank. Then upload and replace the old version.
Privacy first
Every JAD Excel tool runs entirely in your browser using SheetJS and ExcelJS. Your spreadsheets, formulas, and data never leave your device — verified by zero outbound network requests during processing.