This chart is an XY scatter graph. The x-axis is formatted with date/time
format, so I successfully made 0.25 minor tick marks. To label every tick
mark, I had to change my major tick marks to 0.25 also. However, I want
major tick marks for every day and minor tick marks for every 6 hours. But I
also want minor tick marks labelled. You said that I can change the x-axis
format axis to a category-type axis so that I can get the "Number of
categories between
tick mark labels" box in the "Format Axis" Scale tab? If that's what you
mean, then how do I change the x-axis format?

"Jon Peltier" wrote:

Excel stores date-time data as the sum of a whole number (the date, in
days since 1 Jan 1900, give or take a leap day) plus a fraction (the
time, as elapsed since midnight, so 6 am = 0.25).

If you make an XY Scatter chart using this date-time as your X values,
you can do whatever you want, with major ticks at midnight and minor
ticks every 6 hours. You can enter 0.25 for your minor spacing (1/4 day)
or 6:00, and Excel will convert the time to the decimal equivalent. You
can also enter dates for the min or max, and Excel will convert them.

A Line chart has two ways to do this. If Excel recognizes the dates, it
creates a numerical date scale axis (misnamed a "time scale" axis by
Microsoft). It uses only the whole number piece of the data and ignores
the fraction. Your X axis spacing then can be no less than 1 full day,
major or minor spacing, and all points are plotted at midnight at the
start of the day.

A Line chart can also have a category axis which uses each X value entry
as a non-numerical label. Points are equally spaced regardless of the
time difference between points. You can specify a number of categories
between major and minor labels, and if your data consists of four evenly
spaced measurements per 24-hour period, you can approximate a daily
major tick with four minor divisions.

In a Line chart you can change from one category axis type (Category or
Time Scale) by selecting Chart Options from the Chart menu, and clicking
on the Axes tab. You might be better off with an XY Scatter chart. You
can format the points as in a line chart, so don't let an unfortunate
choice of chart type names mislead your choice of chart types.

- Jon
-------
Jon Peltier, Microsoft Excel MVP
Peltier Technical Services
Tutorials and Custom Solutions
http://PeltierTech.com/
_______


Debrane wrote:

How can I increase the quanity of tick mark labels along the x-axis in a
graph? I.E. Excel only puts my Date/Time tick mark labels at the beginning
of each day. I'd like to show tick mark labels every 6 hours.