Height and Weight are important parameter which are examined in Medical Exam at the Service Selection Boards. Candidate must posses minimum acceptable limit of prescribed Height and Weight for that particular age group.
You can measure your height through any ruler and weight by a weighing machine. If your height and weight are within ±10% of the specified limits then it is fine but if it varies more than that then you have to correct it.
If you are declared as unfit on the basis of weight the you will be given 42 days time to reduce your weight and bring it down or up to the specified range.
Below is the table of Height and Weight for different Age Groups.
A 5 cms relaxation is given to Candidates belonging to North East Region of India, Garwahal or Kumaon or Gorkha. Candidates from Lakshwadeep are given relaxation of 2 cms in height. The weight should be within permissible limits of ±10% of the Standard Weight. The principles of average will be utilized for Calculating body Weight for in between Height.