Is it inormal for a 13 yr old to have only 3 day period?

Yes, it can be normal for a 13-year-old to have a period that lasts only three days. Menstrual cycles can vary widely during the first few years after menstruation begins, with some periods being shorter or lighter than others. However, if there are any concerns about irregularities or other symptoms, it's a good idea to consult a healthcare professional for personalized advice.