weight is appropriate for height and is calculated using a simple formular :
BMI = weight(kg)/ [height square(m)]
For example, a person who weighs 65kg and is 1.6m tall would have a BMI of 65kg divided by the square of 1.6m which would be 25.4
The advantage of using this index, rather than weight alone is that, it is height-independent such that tall and short people of similar proportions would have a similar BMI. The World Health Organisation(WHO) regards a BMI of 18.5 to 25 as optimal(normal) weight, a number above 25 suggests overweight and a number above 30 indicates obesity.
However, note that BMI does not measure body fat.
Please, check your height and weight to know your BMI and work towards staying fit.