Double click the y-axis, then from the Scale tab select 'Logarithmic scale'
To create custom "gridlines" see
Flexible Log Scale
http://www.tushar-mehta.com/excel/ne...ale/index.html

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Regards,

Tushar Mehta
www.tushar-mehta.com
Excel, PowerPoint, and VBA add-ins, tutorials
Custom MS Office productivity solutions

In article ,
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I want to plot a semi log plot in excel along with grid lines. Can anyone
tell how to do?