http://www.pro-sieben.de/beauty/1998/1130/kalorien4/ has a BMI calculator form. As a reminder 1pound=0.454kg 1inch=2.54cm (The form expects height in cm not m)
For a woman BMI should be between 19 and 24, for a man 20 to 25. Below 16 means serious underweight (consult a doctor, you're not slim, you have an eating disorder!!) and above 30 means serious overweight. The formula does not work very well for kids/teens who are still growing. MSB