OBJECTIVES: To evaluate an online freeware calculator that generates incremental cost effectiveness ratios and quadrant plots for formulary drug classes. METHODS: This online software results were compared to a published pharmacoeconomic analysis on the cost and effectiveness of several oral triptan drugs for migraines. The web-based, formulary cost effectiveness calculator and grapher is freely available through HDS, www.HealthStrategy.com. The triptan data and analysis was based on a published article by Ho MJ et al, The Role of Pharmacoeconomics in Formulary Management: Triptan Case Study for Migraine, accessible through www.formkit.com/ptjournal. RESULTS: The HDS calculator runs online through most computer operating systems with a JavaScript enabled browser such as Internet Explorer, Firefox, Opera, or Safari. Up to seven different drugs in a class can be compared by inputting the cost and effectiveness per each drug. This Internet tool outputs tables with incremental cost effectiveness ratios and also generates plots such as bar charts and incremental cost effectiveness slopes.  Respective mean ICERs from the Ho article versus HDS, with Eletriptan as the central reference, comparator, were as follows: Rizatriptan:($20.84 vs. $21.62), Zolmitriptan:($24.63 vs. $27.50) Almotriptan:($38.60 vs. $45.67), Naratriptan:($62.11 vs. $88.50), Sumatriptan:(-$63.52 vs. –$62.25 [dominated]), Frovatriptan:($-2.22 vs. -$2.20 [dominated]). ICER bar graphs are available in both reports, but HDS provides ICER quadrant plots, and more clearly presents favorable and dominated options. The Ho article includes more results with sensitivity analyses. CONCLUSIONS: In the current HDS version, the user can enter seven drugs in a class for comparison. The HDS online freeware provides very basic statistical and charting features that may be useful for formulary cost effectiveness comparisons for drugs in the same class.