but my workbook with issues has 215 sheets, after I removed a few to see if that would resolve the issue. My workbook size is a little over 5.5M. This workbook has evolved over the years since around 2001.i
I've had similar issues of workbooks growing to enormous sizes, along with the dreaded "too many cell formats" error, which plagued me for years on older workbooks I've used for many years - tried all of the add-ins and tricks to remove excess styles/formats with no joy - learned a couple key things recently I thought I'd share:
1. Deleting sheets from a book may decrease it's size, but rarely will it resolve the excess format problem.
2. Autosave recovery files in various MS Office programs can be very bloated - best to copy stuff to a new file and delete the recovered one.
3. Excel 2003 charts with large numbers of data points increase file sizes enormously - one workbook I have is 3MB w/o the chart, 8MB w/chart (!?!).
4. Recently ran into some odd problem that gave me the "file validation error", saved it in Excel95/2003 format, and file size DOUBLED from 6MB to 12MB. However, saving as Excel 2003, then reopening it, gives me the "created in newer version of Excel" error, which can be ignored, but is a PITA, something I still haven't figured out how to fix.
Lastly, I finally resolved the excess formatting problem, and it was in a place I've never seen mentioned anywhere on the net (I've been looking for a solutions for years) - it was in the "Custom Styles":
a) put cursor/focus on a cell that has a value and a format applied
b) in the menu dropdown list, choose "format/cells"
c) at the bottom of the number format list, find "custom", click on it
d) scroll down to the bottom of the list - upper items are default formats, bottom of list will be custom formats you've created over time, perhaps from every workbook you've ever created
e) starting at the bottom, highlight a custom format you know you don't need, put a checkmark in the "Delete" box, then click ok. Repeat for all unused custom formats - I found dozens, including % and $ formats to 5 decimal points, and some very odd date/time formats - I know these are carryovers from old work files I brought home, recognized the weird formats we had to create to input data from instrumentation systems that had time/date codes that needed to be converted in order to be plotted in Excel.
Voila! Excess formatting problem solved!
Still looking for solutions to items in #4 above, but they don't prevent me from modifying workbooks, are more of an annoyance than anything else - they started occurring after I downloaded an Excel 2007 file from a stock broker website, believe something got corrupted in my Excel installation during the conversion process, but I'm not about to uninstall/reinstall Office to fix it, have years of customizations that would be lost, not worth it.