Height cm  Weight kg  

Height 166 weight 48
What is the ideal weight for 166 cm tall male or female? Is it normal to weigh 48 kg for this height? Body Mass Index (BMI) will answer these questions. If BMI value is within the range 18.5 – 24.99 (for any height), then the weight is withing normal limits.
For the height 1.66 meters (166 cm) and for the weight 48 kilograms:  

Result:  Lack of weight. 
BMI:  17.42 
Normal weight limits:  51  69 kg. 
What to do?  Gain 3 kg. 
How to calculate BMI and weight ranges on your own?
 BMI formula: weight / height^{2}
 where the height value is in meters (not in centimeters), for example 1.73 (not 173).
 Multiplication first, then division!  For example, if the height is 176 cm and the weight is 63 kg, then BMI = 63 / 1.76 * 1.76 = 20.34. BMI within normal values.
Check yourself. The Height and weight combinations below are normal or not?