Calculating actual humidity using sy-hs 220 humidity sensor
It is unclear what hardware you are using. Let's assume that you're using an Arduino.


Arduino returns ADC values from 0 to 1024 for 0 to 5V.
The humidity sensor returns from 1 to 3V which is 205 to 614 in ADC values.


So using an inbuilt function map(), we get this code:

    int val = analogRead(0);
    val = map(val, 205, 614, 30, 90);