The ideal weight is determined by many things, but mainly how tall you are and what kind structure of the body you have.
Accordingly, there is a table that can help you determine what your ideal weight.
The table includes the average height for women with measurements in centimeter and kilograms, and below you can see a table with measurements for the USA.
This is a table with US customary units (feet, inches and lbs.)
However, keep in mind that these data are statistically so if you think that this figure does not match your ideal weight, you should consult with your doctor.