Ideal Weight Calculator UK 2026
Free UK Ideal Weight Calculator 2025. Find your ideal weight using Devine, Robinson, Miller and Hamwi formulas. Results in kg and stones with NHS ranges.
Last updated: February 2026
Ideal Weight Calculator
Calculate your ideal body weight using four established medical formulas. Results shown in both kg and stones/pounds.
Your Ideal Weight Range
Understanding Ideal Body Weight
Ideal body weight (IBW) is a clinical estimate of what a person should weigh based on their height and gender. These formulas were originally developed for medical purposes such as calculating drug dosages and assessing nutritional needs, but they have become widely used as general health guidelines.
Why Multiple Formulas?
No single formula is universally accepted as the "correct" ideal weight calculation. Each was developed by different researchers using different population data, which is why they give slightly different results. Using all four and looking at the range gives you a more realistic target than relying on any single formula.
The Four Ideal Weight Formulas
Devine Formula (1974)
The most widely used formula, originally developed for drug dosage calculations.
Male: 50.0 + 2.3 x (height in inches - 60)
Female: 45.5 + 2.3 x (height in inches - 60)
Robinson Formula (1983)
A modification of the Devine formula with adjusted coefficients.
Male: 52.0 + 1.9 x (height in inches - 60)
Female: 49.0 + 1.7 x (height in inches - 60)
Miller Formula (1983)
Tends to give slightly higher ideal weights than other formulas.
Male: 56.2 + 1.41 x (height in inches - 60)
Female: 53.1 + 1.36 x (height in inches - 60)
Hamwi Formula (1964)
One of the earliest ideal weight formulas, still commonly used.
Male: 48.0 + 2.7 x (height in inches - 60)
Female: 45.5 + 2.2 x (height in inches - 60)
Ideal Weight Chart (Average of All Formulas)
| Height | Male (kg) | Male (st/lb) | Female (kg) | Female (st/lb) |
|---|---|---|---|---|
| 5ft 0in (152cm) | 52.6 kg | 8st 4lb | 49.0 kg | 7st 10lb |
| 5ft 2in (157cm) | 56.8 kg | 8st 13lb | 52.5 kg | 8st 4lb |
| 5ft 4in (163cm) | 60.9 kg | 9st 8lb | 55.9 kg | 8st 11lb |
| 5ft 6in (168cm) | 65.1 kg | 10st 3lb | 59.3 kg | 9st 5lb |
| 5ft 8in (173cm) | 69.2 kg | 10st 12lb | 62.8 kg | 9st 12lb |
| 5ft 10in (178cm) | 73.4 kg | 11st 8lb | 66.2 kg | 10st 6lb |
| 6ft 0in (183cm) | 77.5 kg | 12st 3lb | 69.7 kg | 11st 0lb |
| 6ft 2in (188cm) | 81.7 kg | 12st 12lb | 73.1 kg | 11st 7lb |
| 6ft 4in (193cm) | 85.8 kg | 13st 7lb | 76.5 kg | 12st 1lb |
Beyond the Numbers: Other Health Indicators
Ideal weight is just one indicator of health. The NHS and medical professionals recommend considering these additional measures:
BMI (Body Mass Index)
Your BMI is calculated as weight (kg) divided by height (m) squared. The NHS categories are: underweight (below 18.5), healthy (18.5-24.9), overweight (25-29.9), and obese (30+).
Waist Circumference
Carrying excess fat around your middle increases health risks. The NHS recommends:
- Men: Below 94cm (37 inches) -- increased risk above 102cm (40 inches)
- Women: Below 80cm (31.5 inches) -- increased risk above 88cm (34.5 inches)
Waist-to-Height Ratio
Some researchers consider this a better predictor of health than BMI alone. A healthy ratio is below 0.5 -- meaning your waist should be less than half your height.
Body Fat Percentage
A more accurate measure of body composition than weight alone. Healthy ranges are approximately 10-20% for men and 18-28% for women, though this varies with age.
Frequently Asked Questions
Ideal body weight is an estimated weight considered healthiest for a person based on their height and gender. Multiple medical formulas exist -- Devine, Robinson, Miller, and Hamwi -- each giving slightly different results. The range between them provides a realistic target zone rather than a single magic number. These were originally developed for clinical purposes like drug dosing.
Ideal weight varies by height and gender. For example, a 5ft 7in (170cm) male has an ideal weight of roughly 60-73kg (9st 6lb to 11st 7lb). A 5ft 4in (163cm) female has an ideal weight of roughly 53-59kg (8st 5lb to 9st 4lb). Use our calculator above for a precise calculation based on your exact height.
Ideal weight formulas provide useful estimates but have limitations. They do not account for muscle mass, body composition, bone density, or ethnic variations. A muscular person may weigh well above their "ideal" yet be in excellent health. Use these results as a general guide alongside BMI, waist circumference, and your GP's professional assessment.
The NHS defines a healthy weight as a BMI between 18.5 and 24.9. For a 170cm person, this means 53.5kg to 72.0kg. The NHS recommends maintaining a healthy BMI alongside a waist circumference below 94cm for men or 80cm for women. For some ethnic groups, lower BMI thresholds may apply.
Most ideal weight formulas use only height and gender. However, body composition changes with age. People naturally lose muscle mass and may gain fat.
Some research suggests a slightly higher BMI (up to 27) may be acceptable for adults over 65, though this remains debated. Regular exercise and strength training can help maintain muscle mass at any age.
"Ideal weight" refers to a target calculated from specific medical formulas, while "healthy weight" is typically a broader range based on BMI 18.5-24.9. Any weight within the healthy BMI range is considered medically acceptable. The ideal weight formulas tend to target the middle of this range. Both are estimates -- your GP can give personalised advice.
NHS Healthy Weight Ranges and BMI Limitations
The NHS defines a healthy weight as a BMI between 18.5 and 24.9. This is the primary measure used by GPs and health professionals across the UK when assessing weight-related health risks. However, BMI has well-documented limitations that are important to understand when interpreting your results.
Known Limitations of BMI
- Muscle mass: BMI does not distinguish between muscle and fat. A muscular person (such as a rugby player or weightlifter) may have a BMI above 25 and be classified as "overweight" despite having a low body fat percentage and excellent cardiovascular health.
- Age: Older adults tend to have more body fat than younger adults at the same BMI. A BMI of 24 at age 70 may represent more fat tissue than the same BMI at age 30.
- Ethnicity: The NHS notes that people from South Asian, Chinese, and Black African or Caribbean backgrounds may have higher health risks at a lower BMI. The World Health Organization suggests using BMI 23 (rather than 25) as the "overweight" threshold for South Asian populations.
- Fat distribution: BMI does not account for where fat is stored. Abdominal (visceral) fat carries significantly higher health risks than fat stored on hips and thighs, but BMI treats all fat equally.
- Children and teenagers: BMI thresholds for adults do not apply to under-18s. Children use age- and gender-specific BMI centile charts instead.
Waist-to-Height Ratio: A Better Indicator?
Research published in the British Medical Journal suggests that the waist-to-height ratio is a more accurate predictor of cardiovascular risk than BMI. The rule is simple: your waist circumference should be less than half your height. For example, a person who is 170cm tall should aim for a waist measurement below 85cm.
The NHS recommends measuring your waist at the midpoint between the bottom of your ribs and the top of your hips (roughly at your belly button level). Healthy waist circumference targets are:
- Men: Below 94cm (37 inches). High risk above 102cm (40 inches).
- Women: Below 80cm (31.5 inches). High risk above 88cm (34.5 inches).
Healthy Weight by Height Table (BMI 18.5 - 24.9)
The following table shows the NHS healthy weight range for each height, calculated using BMI boundaries of 18.5 and 24.9. These ranges apply to adults of all genders.
| Height | Min Healthy Weight (BMI 18.5) | Max Healthy Weight (BMI 24.9) | Healthy Range |
|---|---|---|---|
| 5ft 0in (152cm) | 42.7 kg (6st 10lb) | 57.6 kg (9st 1lb) | 42.7 - 57.6 kg |
| 5ft 1in (155cm) | 44.4 kg (7st 0lb) | 59.9 kg (9st 6lb) | 44.4 - 59.9 kg |
| 5ft 2in (157cm) | 45.6 kg (7st 2lb) | 61.4 kg (9st 9lb) | 45.6 - 61.4 kg |
| 5ft 3in (160cm) | 47.4 kg (7st 6lb) | 63.8 kg (10st 0lb) | 47.4 - 63.8 kg |
| 5ft 4in (163cm) | 49.1 kg (7st 10lb) | 66.2 kg (10st 6lb) | 49.1 - 66.2 kg |
| 5ft 5in (165cm) | 50.4 kg (7st 13lb) | 67.8 kg (10st 9lb) | 50.4 - 67.8 kg |
| 5ft 6in (168cm) | 52.2 kg (8st 3lb) | 70.3 kg (11st 1lb) | 52.2 - 70.3 kg |
| 5ft 7in (170cm) | 53.5 kg (8st 5lb) | 72.0 kg (11st 5lb) | 53.5 - 72.0 kg |
| 5ft 8in (173cm) | 55.4 kg (8st 10lb) | 74.5 kg (11st 10lb) | 55.4 - 74.5 kg |
| 5ft 9in (175cm) | 56.7 kg (8st 13lb) | 76.3 kg (12st 0lb) | 56.7 - 76.3 kg |
| 5ft 10in (178cm) | 58.6 kg (9st 3lb) | 78.9 kg (12st 6lb) | 58.6 - 78.9 kg |
| 5ft 11in (180cm) | 60.0 kg (9st 6lb) | 80.7 kg (12st 10lb) | 60.0 - 80.7 kg |
| 6ft 0in (183cm) | 62.0 kg (9st 11lb) | 83.4 kg (13st 2lb) | 62.0 - 83.4 kg |
| 6ft 1in (185cm) | 63.3 kg (9st 13lb) | 85.3 kg (13st 6lb) | 63.3 - 85.3 kg |
| 6ft 2in (188cm) | 65.4 kg (10st 4lb) | 88.0 kg (13st 12lb) | 65.4 - 88.0 kg |
Body Composition Factors
Your body weight is made up of several components, each of which affects your health differently:
- Lean body mass (muscle, bones, organs): Higher lean mass is generally associated with better metabolic health, stronger bones, and greater functional ability. Resistance training helps maintain lean mass, which naturally declines with age.
- Body fat: Essential fat (needed for organ function and hormone production) is approximately 3-5% for men and 10-13% for women. Healthy body fat ranges are typically 10-20% for men and 18-28% for women. Excess body fat, particularly visceral fat around the abdomen, is linked to type 2 diabetes, heart disease, and certain cancers.
- Water: Around 50-60% of body weight is water. Hydration levels fluctuate daily and can cause weight to vary by 1-2 kg in a single day, which is why weighing yourself at the same time each day gives more consistent readings.
- Bone density: People with denser, heavier bones will naturally weigh more at the same body fat percentage. Bone density is influenced by genetics, exercise, diet, and hormones.
Worked Examples: Ideal Weight Scenarios
Example 1: Sarah, 5ft 4in (163cm), Female
Using our calculator, Sarah's ideal weight results are:
- Devine formula: 55.9 kg (8st 11lb)
- Robinson formula: 56.8 kg (8st 13lb)
- Miller formula: 57.2 kg (9st 0lb)
- Hamwi formula: 54.3 kg (8st 8lb)
- Average ideal weight: 56.1 kg (8st 11lb)
The NHS healthy range for 5ft 4in is 49.1 - 66.2 kg, so Sarah has a comfortable target range to aim for. Her ideal weight falls right in the middle of the NHS range, suggesting the formula average is a reasonable goal.
Example 2: James, 5ft 10in (178cm), Male
James is a regular gym-goer who weighs 85 kg. His calculator results show:
- Devine formula: 73.0 kg (11st 7lb)
- Robinson formula: 71.2 kg (11st 3lb)
- Miller formula: 72.3 kg (11st 5lb)
- Hamwi formula: 75.0 kg (11st 11lb)
- Average ideal weight: 72.9 kg (11st 6lb)
The NHS healthy range is 58.6 - 78.9 kg. At 85 kg, James is technically above the healthy BMI range. However, because he trains regularly, much of his additional weight is muscle.
His waist circumference is 84cm (well below the 94cm threshold), suggesting he is at low health risk despite his BMI being slightly elevated. This illustrates why BMI alone should not be used to assess health.
Example 3: David, 6ft 1in (185cm), Male, Age 55
David is sedentary and weighs 98 kg. His results are:
- Devine formula: 78.8 kg (12st 5lb)
- Robinson formula: 76.0 kg (12st 0lb)
- Miller formula: 77.6 kg (12st 3lb)
- Hamwi formula: 81.5 kg (12st 11lb)
- Average ideal weight: 78.5 kg (12st 5lb)
The NHS range is 63.3 - 85.3 kg. At 98 kg with a waist circumference of 106cm, David is above both the healthy BMI range and the healthy waist threshold. His GP would likely recommend gradual weight loss of 0.5-1 kg per week through dietary changes and increased physical activity. A realistic first target would be to reach 85 kg to enter the healthy BMI range.
More Questions About Ideal Weight
For most people, aiming for anywhere within the NHS healthy BMI range (18.5-24.9) is more practical and sustainable than targeting a single "ideal" number. The formula-based ideal weights give you a midpoint target, but any weight within the healthy range is associated with lower risk of weight-related diseases. Focus on gradual, sustainable changes rather than hitting an exact number. Your GP can help you set a personalised target based on your individual circumstances.
The standard ideal weight formulas were developed using data from younger adult populations and do not account for age-related changes in body composition. As people age, they tend to lose muscle mass and gain fat, even if their weight remains stable. Some research suggests that a slightly higher BMI (around 25-27) may actually be protective in older adults, as it provides energy reserves during illness. If you are over 65, discuss your target weight with your GP rather than relying solely on formula calculations.
Yes, though home methods have varying accuracy. Bioelectrical impedance scales (available from £20-50) estimate body fat by sending a small electrical current through your body. They are convenient but can be affected by hydration levels and are typically accurate to within 3-5 percentage points.
Skinfold callipers are more accurate when used correctly but require practice. For the most precise measurement, a DEXA scan (available privately for £100-200) or hydrostatic weighing provides accuracy within 1-2%. For tracking trends over time, any consistent method works well.
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Last updated: February 2026 | Reviewed for accuracy against NHS healthy weight guidelines
Sources Checked -- This calculator is checked against official published sources and updated regularly with the latest NHS guidelines. Last verified: February 2026.