Auto y-scale not working correctly?

[JohanS]

I have a simple line graph with two data series. The one series has a lowest value of 12,04 and a highest value of 14,05. The second series has a lowest value of 11,36 and a highest value of 12,39. If I selct Auto scaling for Y-axis the Minimum, Maximum, Major Unit and Minor Unit the minimum goes to 0 (and the Maximum to 16) whilst a more appropriate minimum would be say 10 to 11. If I use the exact same graph but now the range of values for the two series are 4,47 to 4,80 and 5,01 to 5,02 respectively, the scale minimum goes to 4,10 (and maximum to 5,10). So in this case the auto scale does not force the minimum to 0. Can anyone shed light on this problem?

 

[Steve=True]

Hello JohanS and welcome to the forums.

It is not that it is broken, but it is how it works.

If the difference is about 20% then it will narrow your axis. If the difference is larger than 20% then you will have the Zero as the minimum.

Be careful with axis not down to zero as you can skew the graph look and distort it for your viewers.

John P did a good post about this on his site: http://peltiertech.com/WordPress/

Hope this helps.

Steve=True

 

[Steve=True]

Here is the article:

[h=2]How Excel Calculates Automatic Chart Axis Limit[/h]