An opacity engine for automatically and dynamically setting an opacity level for a scatterplot based on a predetermined value for a mean opacity level of utilized pixels (MOUP) in the scatterplot. The opacity engine may automatically set the opacity level for the scatterplot to produce the predetermined MOUP value in the scatterplot. A utilized pixel in the scatterplot comprises a pixel displaying at least one data point representing data. The MOUP value in the scatterplot may be equal to the sum of the final opacity levels of all utilized pixels in the chart, divided by the number of utilized pixels in the chart. The predetermined MOUP value may be between 35%-45%, such as 40%. The opacity engine may adjust the determined opacity level for charts having relatively low over-plotting factors.