What is my bmi? 5'4 278 wrist size is 7

47.7. You bmi is very high. You need a good medical evaluation, and then to begin a program of education, diet and exercise. Otherwise your risks of medical problems (diabetes, blood pressure, cholesterol, stroke, orthopedic disorders, etc) will be dangerously high and you will feel miserable. You're still young enough to save your life by getting healthier. Start now!