Page Size changes between PowerPoint 2002 and older versions
If your system uses centimetres instead of inches, your PowerPoint slide and other page sizes may change when you
- Open presentations created in older versions of PowerPoint in PowerPoint 2002/XP
- Open presentations created in PowerPoint 2002/XP in older versions of PowerPoint
In most cases, it won't cause any real problems.
Or change the page setup/slide setup size back to the original dimensions. Since this will be proportional in size, PowerPoint will not usually change the contents of your slides as a result.
Why it happens
PowerPoint storess size information in points (72 points to the inch) internally, no matter what system of units your computer is set for.
Older versions of PowerPoint used an incorrect factor (2.4 cm/inch) for converting inches and points to cm and mm. See CENTIMETERS in PowerPoint are wrong for more information about this.
PowerPoint 2002 uses a more accurate conversion factor ( 2.54 cm/in ) instead.
When you set up a 20cm page size in PowerPoint 2000 or earlier, PowerPoint stored the page size internally as 20 / 2.4 or 8.333 inches ( actually 8.333in * 72 or 600 points )
When you open this presentation in PowerPoint 2002, it converts:
600 points / 72 = 8.333 in
8.333 in * 2.54 = 21.166 cm
Your page size turns up as 21.16cm instead of 20cm.