See the years of life with my Lifespan Calculator©! Answer the questions correctly and you'll get the results! Enter your answer using one of the choices exactly as it's featured on the backdrop unless it says otherwise. The reason why is because every possible answer is put into the project. How to calculate your BMI: Weight(kilograms) ÷ Height(meters) ÷ Height(meters) Do not enter your BMI in decimals, but in whole numbers.