What is equivalent dosage of Citalopram compared to 100 mg of Zoloft

I looked up a few papers and tables and found different perspectives. Generally, citalopram is allowed in the range of 20-40 mg, and zoloft 50-200. In one table, it was stated that the starting dose of citalopram is 20 and zoloft is 50, which is quite logical. From that, I can infer that 100 zoloft is 20+20 = 40 mg of citalopram, but it looks quite doubtful because 40 is the max dosage.

Furthermore, I found one study in which citalopram and zoloft were compared in the ranges of 20-40 and 50-100 respectively. In another study, they were 20-40 and 50-150. I’m still a bit confused. I took 40 mg for a couple of days and it didn’t strike me with a surge of apathy, but I felt it definitely more potent than just 100 mg of zoloft.