Autoscaling Behaviors of the FileMaker Pro Chart Object

Ever have a FileMaker Pro chart “mysteriously” change its scale setting on you? Ever wonder how the FileMaker Pro chart object decides to set the y-axis scale? The FileMaker Pro documentation doesn’t provide that level of detail, so following are the behavior “rules” I’ve deduced through experimentation:

Scaling Behavior “Rules”…
(The following assume the y-scale min-max has not been set to static values.)

  • If the spread of values is less than 20%, the y-axis min-max will automatically adjust to show just the top portion of the plot.
  • If the high value is more than 90% of the y-axis max, the chart draws to the next larger grid line (which has its own set of display logic, by the way).
  • If the low value is less than ~14% of the visible scale, the chart draws to the next smaller grid line.

To experiment with settings on variously-sized charts download the demo file.

Happy exploring, and stay savvy!


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