Hah!! Ok then - to be precise ..

..xlsm file = 2.5mb
..xlsb file = 1.6 mb

therefore 30%+ could be construed as much :)

Many thanks for the response. I'll check the blog. Have a good weekend!

"JLatham" wrote:

See this MSDN Blog page for a discussion of Excel 2007 file formats, which
should help a little:
http://blogs.msdn.com/excel/archive/...20/671995.aspx

I note that the author states, in the XLSB discussion, that "file size of
both formats is approximately the same, since both formats are saved to disk
using zip compression" However this discussion was prepared in 2006, so
changes in the actual format may have taken place after this was written that
resulted in a more compact file size for the binary files?? Then again, you
said "...much larger..." and "much" is often a relative term.

"Bony Pony" wrote:

Hi all,
Anyone know why the file size for a .xlsm version of a wbook is much larger
than a .xlsb?

I know xlsb is a binary "raw" save so I would have thought it would require
more space? I also thought the other formats compressed the file too so I'm
puzzled all round.

Regards,
Bony