In this paper, the authors design a microcontroller based automated Body Mass Index (BMI) calculator with LCD display, which calculates the body mass index using the two basic parameters that are weight and height. The hardware of the project consists of a weighing mechanism i.e. weighing machine, which is used to calculate the body weight of a person, and a height sensing mechanism i.e. LDR (Light Dependent Resistor), which is used to calculate the height of a person. The weight of the person is calculated in Kilograms and the height in meters in accordance of the BMI standard formula.