Ideal Weight Calculator | Healthy Weight for Height
Ideal Weight Calculator for men and women
Our Ideal Weight Calculator uses three clinically recognised formulas — Devine, Robinson, and Miller — alongside a healthy BMI range to estimate the weight that may be most appropriate for your height and sex. Simply enter your details above to get your personalised result in seconds. Understanding where your weight sits relative to a healthy range can be a useful first step in supporting long-term health and wellbeing.
Ideal Weight Calculator
Find your ideal weight range using clinically established formulas (Devine, Robinson, Miller) and healthy BMI range for your height.
Ideal Weight by Formula
| Formula | Ideal Weight | Notes |
|---|---|---|
| Devine (1974) | -- | Widely used in clinical settings |
| Robinson (1983) | -- | Refined from Devine formula |
| Miller (1983) | -- | Alternative clinical estimate |
| Hamwi (1964) | -- | Traditional rule-of-thumb |
| Healthy BMI Low (18.5) | -- | Lower healthy BMI boundary |
| Healthy BMI High (25.0) | -- | Upper healthy BMI boundary |
Your BMI Summary
| Metric | Value | Category |
|---|---|---|
| Your Current BMI | -- | -- |
| Average Ideal Weight | -- | Mean of all formulas |
| Weight Difference | -- | -- |
This calculator provides estimates for general informational purposes only and does not constitute medical advice. Results are based on population-level formulas (Devine 1974, Robinson 1983, Miller 1983, Hamwi 1964) and healthy BMI ranges; individual results may vary based on muscle mass, bone density, age, and other clinical factors. Please consult a UK-registered prescriber or healthcare professional before making any changes to your diet, exercise, or treatment plan.
What's on this page?
How does our Ideal Weight Calculator work?
Our Ideal Weight Calculator draws on four separate estimation methods to give you a rounded picture rather than a single rigid number. The Devine formula, originally developed in 1974 for clinical drug dosing, calculates ideal body weight as 50 kg (men) or 45.5 kg (women) for a height of 5 feet, adding 2.3 kg for every inch above that baseline. The Robinson formula (1983) and Miller formula (1983) use slightly different starting points and increments, reflecting the fact that no single equation fits every body type perfectly. Alongside these three formulas, the calculator also displays the weight range that corresponds to a BMI of 18.5–24.9 — the band the NHS and World Health Organization consider healthy for most adults.
Because the three formulas were originally derived from studies of hospital patients rather than the general population, their outputs can differ by several kilograms. Presenting all three together — plus the BMI-derived range — gives you a more realistic window of healthy weight rather than a false sense of precision. Your result should be read as a guide, not a target set in stone.
Factors that affect your ideal weight beyond height
Height and sex are the starting inputs for any ideal weight formula, but several other factors influence what a genuinely healthy weight looks like for you as an individual. The figures produced by our Ideal Weight Calculator are population-level estimates and may not fully account for the following personal characteristics.
- Muscle mass — athletes and people with high muscle mass may weigh more than the formula suggests while carrying very little body fat.
- Age — older adults naturally lose muscle and gain fat over time, meaning the same scale weight can represent a different body composition at 25 versus 65.
- Ethnicity — research published in journals such as The Lancet suggests that people of South Asian, East Asian, and Black African heritage may face health risks at lower BMI thresholds than the standard 25 cut-off.
- Bone density and frame size — a larger skeletal frame contributes more to overall weight, which the basic formulas do not adjust for.
- Pregnancy and breastfeeding — standard ideal weight ranges do not apply during or immediately after pregnancy.
- Medical conditions — certain conditions such as hypothyroidism, PCOS, or fluid retention can affect weight independently of diet and activity.
What to do with your Ideal Weight Calculator result
Receiving a number from our Ideal Weight Calculator is most useful when you treat it as the beginning of a conversation about your health rather than a verdict. If your current weight falls within or close to the estimated range, continuing your existing healthy habits — balanced nutrition, regular physical activity, and adequate sleep — is generally the best approach. If your weight sits noticeably above or below the range, speaking with your GP or a registered dietitian is the recommended next step before making any significant changes to your diet or exercise routine.
Practical steps if your weight is outside the healthy range
If your weight is above the estimated healthy range, small, sustainable changes tend to produce better long-term outcomes than rapid diets. The NHS recommends aiming for a calorie deficit of around 500 kcal per day, which may lead to a loss of roughly 0.5 kg per week on average. Increasing whole foods, reducing ultra-processed foods, and building up to at least 150 minutes of moderate aerobic activity each week are evidence-backed starting points. Your GP can also refer you to the NHS Weight Management Programme or, where clinically appropriate, discuss options such as prescription weight-loss medication.
If your weight is below the estimated healthy range, unexplained low weight warrants a GP assessment to rule out underlying causes such as malabsorption, disordered eating, or thyroid dysfunction. A registered dietitian can help you increase calorie and nutrient intake safely and in a way that supports muscle gain rather than simply adding body fat.
Limitations of the Ideal Weight Calculator and when to seek advice
No single calculator — however well designed — can replace a clinical assessment. The Ideal Weight Calculator on this page does not measure body fat percentage, visceral fat, waist circumference, blood pressure, or blood glucose, all of which contribute to a full picture of metabolic health. Research consistently shows that waist-to-height ratio (aiming for waist circumference less than half your height) can be a stronger predictor of cardiovascular risk than weight alone, yet it falls outside what any weight-for-height formula can capture.
You should consult your GP or a qualified healthcare professional if you are concerned about your weight, if your weight has changed significantly without an obvious reason, if you have a pre-existing medical condition, or if you are considering any form of structured weight management programme. This tool is intended to support general health awareness and should never be used as the sole basis for clinical decisions.
Frequently Asked Questions
Sources
- Healthy weight — BMI and healthy weight explained NHS [accessed 26 August 2026]
- Obesity: identification, assessment and management (CG189) NICE [accessed 26 August 2026]
- Devine BJ. Gentamicin therapy. Drug Intelligence & Clinical Pharmacy, 1974 PubMed / NCBI [accessed 26 August 2026]
- Robinson JD et al. Determination of ideal body weight for drug dosage calculations. American Journal of Hospital Pharmacy, 1983 PubMed / NCBI [accessed 26 August 2026]
- Miller DR et al. Ideal body weight calculation. American Journal of Hospital Pharmacy, 1983 PubMed / NCBI [accessed 26 August 2026]
- Body mass index and all-cause mortality — systematic review The Lancet [accessed 26 August 2026]
- Ethnicity and BMI — guidance on lower intervention thresholds for South Asian, Chinese, and other Asian populations NICE [accessed 26 August 2026]
- Waist-to-height ratio as a predictor of cardiometabolic risk British Nutrition Foundation [accessed 26 August 2026]
- Weight management: lifestyle services for overweight or obese adults (PH53) NICE [accessed 26 August 2026]
- BMI healthy weight calculator NHS [accessed 26 August 2026]
Related Weight Loss Treatments
This calculator provides an estimate for general informational purposes only and is not medical advice. Always consult a qualified healthcare professional before making changes to your diet or starting any weight loss treatment.