You're welcome.

I don't understand what you did in that online power program, and my version of Java blocks it as not meeting high safety standards, so I can't try it! How can you know chi-square before running the study? You don't care what the sample size would be to make an observed chi-square significant. You need a site that lets you enter the percentages of interest and the sample sizes, then outputs power. I think it will be hard to find one that tells you sample sizes for unequal groups. Be sure you have chi-square that compares groups, not goodness of fit. If all of this sounds like meaningless jargon to you, I think you need an actual consultant, not a web page (and not just TalkStat help).

First of all, recognize that when sample sizes are unequal, power is mostly related to the harmonic mean of the sample sizes.

The harmonic mean of x and y is found by averaging (in the normal way) 1/x and 1/y, then inverting the result.

So for 55 and 100 subjects, the harmonic mean is 71, almost in the middle of them.

But for 55 and 400 subjects, the harmonic mean is 97, only a bit higher.

For 55 and 10,000 subjects, the harmonic mean is 109. You can see that diminishing returns sets in. At some point the calculation says, "Hey you only have 55 in one group. That's the limiting factor."

You may want to download something like Gpower and play with that. Be sure you understand what it is doing and that it makes sense.

I could show you the formula, but it's not simple.

Ed