What is a healthy weight for my height?

Unfortunately, the official standards of what is a healthy weight appear to be overly generous. Both the College Study and a 14-year study of nearly 116,000 women conducted by the Harvard School of Public Health find that even if you're within the bounds of what the charts say is a healthy or desirable weight, you may still be at higher risk for heart disease and a host of other obesity-related health problems if you're near the upper limit. For example, if you are a man, 35 years of age or older, stand 5 feet 10 inches, and weigh 179 pounds (BMI of 25.4), you're within the bounds of what is considered a "healthful" weight, according to the USDA standards. But it appears your risk of heart disease is still significantly higher than the risk experienced by your leaner peers, those with a BMI of about 21. The bottom line? Leaner is better.

For a healthy weight for your height, in general, it seems you should weigh about 20 percent less than the standard height/weight charts indicate is within the desirable range for you; that is, you should strive for a body mass index (BMI) of about 22 if you're a man or 21 if you're a woman. If you're a woman and stand 5 feet 4 inches, for example, then for optimal health you should weigh no more than about 122 pounds; if you're a man and stand 5 feet 10 inches, you should weigh no more than about 157 pounds, or about 170 pounds if you stand 6 feet 2 inches, assuming average muscle mass. Because muscle weighs more than fat, however, a very muscular person may have a high BMI, but be quite healthy.

The body mass index (BMI) calculation is the easiest way to get an idea of a healthy weight for your height.  The calculation is:
[weight in pounds ÷ inches squared] × 703 = BMI
A healthy BMI score is between 19 and 24.9. 
We can reverse the calculation in order to calculate a healthy weight range:
o First square your height in inches.  Then multiply be 0.027 (this number comes from a BMI of 19 divided by 703).  This is the lower end of your healthy weight range.
o Then take your height in inches squared and multiply by 0.0354 (calculated using a BMI of 24.9 divided by 703).  This will give you the high end of your healthy weight range.
Example for a 5’6” person (66 inches):
66 x 66 = 4356.
4356 x 0.027 = 117.7
4356 x 0.0354 = 154.2
o The healthy weight range for this person is 117.7 – 154.2 pounds.

BMI is a great tool for measuring healthy weight to height in most people but I wanted to add another thing.

The better in shape you get and the closer you get to your weight goal I would advice finding a reputable fitness professional that can accurately test your body fat percentage.  For many fitness enthusiasts that get in great shape they will have a phenomenal fat to muscle ratio and because they are in shape their weight may not be extremely low because they carry a higher percentage of muscle.

Lets say we have two females, each are 68 in tall.  One weighs 120 lbs and has a body fat of 30% and the other is 125 lbs and has a body fat of 20%.  Doing the math we will find that the first has about 36 lbs of fat and lean mass of 84 lbs.  The second person although heavier has only 25 lbs of fat and lean mass of 100 lbs.  The second person  believe it or not will be smaller and fit into smaller clothes because they are more dense and compact and toned and tight.

The example given above is great and BMI is a great tool for those who are overweight and looking to lose weight and be healthier.  However once you get in good shape I would encourage you to start to go more toward body fat testing once you are in a healthy range in your BMI.