One measure generally considered useful is BMI. A BMI in the 18.5-22 range is considered to be one biomarker of health (among several). NIH has an online BMI calculator
here. Jeff Novick's examination of BMI is in
this thread.
Alternatively, you could use the Kempner Foundation weight charts that Dr. McDougall discusses in
this newsletter to get a general idea.
Ideally, a particular BMI or "goal weight" shouldn't really be a target in and of itself, but rather come as the result of following a healthful pattern of eating and behavior.
Hope that helps!