Hi,
I’m an high school senior (Asian female) looking to apply to Caltech EA.
I have a high SAT and ACT scores (1570 and 35), good grades (all A’s with extremely rigorous IB and AP course load), 5’s on all of my AP exams, and solid EC’s as well. However, my concern is that my subject test scores were not as high as I hoped. (790 math and 730 chemistry) The Caltech website said that the middle 50% of students had 780-800 on chemistry, and 800 on math. How badly are my subject test scores going to affect me? Any input would be extremely appreciated! Thank you so much in advance!
Caltech will look at your academic record holistically. 730 on Chem Subject Test is a little low, but how well did you do in chemistry otherwise? Was AP Chem among the AP exams you took? Why did you choose to take chem as one of the subject tests? Do you intend to major in chemistry or a chemistry-related field? Another remedy is to take the upcoming Oct test on chem or another science subject.
Caltech is not a slam dunk for anyone. So you’re going to be in the same boat as everyone else- you need a well balanced list of match and safety schools now that you know your “maybe” school is CalTech.
It’s hard to tell if we don’t know your EC’s. They may or may not compensate for the chemistry score.
I took IB Chemistry HL, and I did not take the AP chem exam. I was able to maintain an A in the class all year long, so I decided to take SAT chemistry, hoping for a fairly high chemistry subject test score. But things didn’t go as expected. 
I’m signed up to retake chemistry for the August SAT, but I’m not entirely confident anymore. Is a perfect score really necessary as some people say? Or would a <770 be sufficient?
I would also take the Math II again also in hopes of getting an 800. You don’t need perfect on Chemistry, but ~770 sounds better.
790 in math is fine and you don’t want adcoms questioning your idea you need perfection. The 730 is, however, low. Assuming your ECs are brilliant (and that’s incredibly rare) and your self presentation is perfect, (again, rare,) you’d be safer with a 750+.
The real question is why Caltech and how well do you know whether you do match? Are your ECs truly solid for Caltech and considering the competition- or just in your own hs context?
Or how about take another Stemmy subject test, say bio?