The weight standard for a 13-year-old girl is around 28.78kg-61.42kg. Weight within two standard deviations is considered normal, and medical attention is recommended if it is abnormal. The standard weight for a 13-year-old girl is around 28.78kg-61.42kg. Weight within two standard deviations above and below the standard weight is generally considered normal for development. Weight is related to genetic, environmental and nutritional factors. 13 year old girls are considered to be at an ideal weight if they are within 10% above or 10% below the standard weight. A weight of 20% above the standard weight is considered mildly obese, 30% above the standard weight is considered moderately obese, and 50% above the standard weight is considered severely obese. If the growth and development of 13-year-old girls from the normal standard gap is too large, parents need to take their children to the hospital in a timely manner for consultation, to find the specific causes, and under the guidance of the doctor for targeted treatment.