How would i know if my blood pressure is too low?

Out: If your pressure becomes too low and you are upright, you are likely to pass out(hypotensive syncope). Too low blood pressure is relative also.

Dizzy Miss Lizzy: When our blood pressure drops too low, we feel dizzy and lightheaded. Sometimes our heart may start racing (palpitations). We may notice it more when we change positions: sitting up in bed, or getting up from a chair to stand. Checking your blood pressure will give you the info you need.