For those who want to convert their practice test scores into SSAT percentile, I am posting a rough trendline based on SSAT scores/percentiles I could find. You can put this trendline into Excel spreadsheet or use it on a calculator.
y = 3E-05x2.399
y equals 100-percentile
x equals 2400-score
This trendline has an R2 = 0.9551, meaning it s not perfect but very close. Following are some reported scores/percentiles compared with predicted percentiles.