Body mass index (BMI) is frequently used in the medical sciences as a measure of adiposity. BMI is the weight (in kg) divided by the square of the height (in meters). In contrast, formulas for ideal body weight (IBW) exist that are linear in the height. Here we obtain new formulas for ideal body weight for height by choosing a more mathematically appropriate reference height. We compare the BMI and IBW formulas by means of the ANSURII database, and show that the IBW formula presented here leads to lower percentage discrepancies in the calculation of the IBW compared to previous formulas.