How Ideal Weight Formulas Work
Ideal weight formulas were originally developed for medical and pharmaceutical dosing purposes rather than as fitness targets. The Devine formula, the most widely used, calculates ideal weight as a base amount for the first 5 feet of height plus an increment for each additional inch. The Robinson, Miller and Hamwi formulas use similar approaches but with different coefficients, producing a range of results that typically span 5 to 10 kilograms for any given height.
These formulas have limitations. They were developed using data from specific populations and may not be equally applicable to all ethnic groups, body types and ages. They do not account for muscle mass, which means a well-trained athlete may appear overweight by formula standards while actually having excellent body composition. Use the results as a general reference point rather than an absolute target, and consider body fat percentage and waist circumference as complementary measures.
Setting Realistic Weight Goals
Rather than fixating on a specific number, health professionals increasingly recommend focusing on a healthy weight range and overall wellbeing. The BMI healthy range of 18.5 to 24.9 corresponds to a weight range for your height that provides flexibility. Within this range, your optimal weight depends on your individual body composition, fitness level and how you feel and function day to day. A weight at which you have good energy, sleep well, exercise comfortably and maintain stable blood markers is a better target than an arbitrary number from a formula.
If you are currently above your healthy weight range, even a modest reduction of 5 to 10 per cent of your body weight can produce significant health improvements. Studies consistently show that this level of weight loss reduces blood pressure, improves cholesterol levels, enhances insulin sensitivity and reduces the risk of developing type 2 diabetes. Setting incremental targets rather than a distant final goal makes the process more manageable and keeps you motivated with regular achievements.
Beyond the Number on the Scales
Weight alone is a poor measure of health and fitness progress. If you start a resistance training programme while eating in a moderate calorie deficit, you may build muscle while losing fat, resulting in minimal change on the scales despite a visible transformation in your body shape and clothing fit. Measuring progress through photographs, body measurements, how your clothes fit and performance improvements in the gym provides a much more complete and motivating picture than weight alone.
Assess your body composition more thoroughly with our body fat calculator, or check your BMI using the BMI calculator. For NHS weight management support and resources, visit NHS Healthy Weight.
This calculator provides estimates for general information only. It is not a substitute for professional medical advice, diagnosis or treatment. Always consult your GP or a qualified health professional before making changes to your diet or exercise routine. See the NHS website for official health guidance.