Summary: Find Your Ideal Weight Free and Privately
An ideal weight calculator estimates a reference body weight from your height and sex. This free ideal weight calculator shows four classic ideal body weight (IBW) formulas side by side: Devine, Robinson, Miller and Hamwi. It adds a frame-size adjustment, the range and average across the formulas, and the weight range that matches a BMI of 18.5 to under 25 for your height.
The calculator runs in your browser; nothing is uploaded (you can check the Network tab in DevTools). It stores nothing between visits. The results are population estimates for adults, not medical advice.
Every formula has the same shape: IBW = base weight at 5 ft + a fixed amount × inches over 5 ft. A man 175 cm tall is about 8.9 inches over 5 ft, so Devine gives 50 + 2.3 × 8.9 = 70.5 kg. To compare this with your own body composition, try the BMI calculator and the body fat calculator.
Table of Use: Ideal Weight Examples
| Scenario | What you enter | Result |
|---|---|---|
| Man, metric | Male, 175 cm, medium frame | 68.7 - 72.0 kg, average 70.0 kg; BMI range 56.7 - 76.6 kg |
| Woman, metric | Female, 165 cm, medium frame | 56.4 - 59.8 kg, average 57.7 kg; BMI range 50.4 - 68.1 kg |
| Small frame | Female, 165 cm, small frame | 50.8 - 53.9 kg; the BMI range stays 50.4 - 68.1 kg |
| Large frame | Male, 180 cm, large frame | 78.7 - 85.1 kg, average 81.5 kg |
| Imperial units | Male, 5 ft 10 in, medium frame | Devine 160.9 lb; range 155.0 - 165.3 lb |
| Below 5 ft | Any sex, 150 cm | No number; a message explains the formulas start at 5 ft |
Features
The four built-in formulas, with weights in kilograms and heights measured over 5 ft (60 in):
| Formula | Men | Women |
|---|---|---|
| Devine (1974) | 50 + 2.3 per inch | 45.5 + 2.3 per inch |
| Robinson (1983) | 52 + 1.9 per inch | 49 + 1.7 per inch |
| Miller (1983) | 56.2 + 1.41 per inch | 53.1 + 1.36 per inch |
| Hamwi (1964) | 48 + 2.7 per inch | 45.5 + 2.2 per inch |
- Range and average. The result panel shows the lowest and highest of the four estimates, their average, and each formula separately.
- Healthy BMI range. The weight at BMI 18.5 and just under 25 for your height, shown beside the formulas and not adjusted for frame.
- Frame Size. Small subtracts 10% and large adds 10% on every formula, following Hamwi's rule.
- Metric or imperial. Enter centimetres, or feet and inches, and read the answer in kg or lb.
- Input checks. Heights below 5 ft (152.4 cm) or above 275 cm get a message, as do metres typed into the centimetre box and 12 or more inches beside a feet value.
- Copy. One button copies the range, each formula and the BMI range as text.
How to Use the Ideal Weight Calculator
- Choose Metric (cm, kg) or Imperial (ft/in, lb).
- Press Male or Female, because each formula has separate constants.
- Type your Height (cm), or Feet and Inches.
- Pick a Frame Size, or leave it on medium if you are unsure.
- Read the range in Ideal Weight Results, compare the four formulas and the healthy BMI range, and press Copy to keep a note.
To switch between units, use the weight converter, the length converter or the general unit converter. For daily energy needs, see the calorie calculator.
Who Can Use It
- Adults curious about a reference weight for their height, who want several estimates rather than one.
- People planning a goal who want a sense of scale. Work out a percentage of body weight with the percentage calculator, and count the days to a target with the date difference calculator.
- Students comparing how linear IBW formulas differ.
It is for adults only. It is not a clinical tool, so do not use it for medication dosing or to set a weight target without advice from a doctor or dietitian.
FAQs
How is ideal body weight calculated?
Each formula starts from a base weight at 5 feet (152.4 cm) and adds a fixed amount for every inch above that. The Devine formula is 50 kg + 2.3 kg per inch over 5 ft for men and 45.5 kg + 2.3 kg per inch for women, so a 5 ft 10 in man gets 50 + 2.3 × 10 = 73 kg.
Which ideal weight formula should I use?
No single formula is "right". Devine is widely quoted in medicine, while Robinson and Miller were fitted to later height-weight data and Hamwi is an older rule of thumb. Looking at the range across all four, together with the healthy BMI range, gives a more realistic picture than any one number.
Why do the ideal weight formulas give different results?
They were built from different data and use different increments per inch. Miller starts highest but adds the least per inch, so it gives the highest estimate for shorter people and a lower one for taller people. Hamwi adds the most per inch for men, so it gives the highest estimate for tall men.
How does frame size change my ideal weight?
Following Hamwi's rule, a small frame subtracts 10% and a large frame adds 10%; this calculator applies that to all four formulas but not to the BMI range. To estimate your frame, wrap your thumb and middle finger around your wrist: overlapping suggests small, just touching medium, and a gap large.
Why does the calculator not work below 5 feet?
All four formulas are defined from 5 ft (152.4 cm) upwards, and extending their lines below that gives unreliable values. The calculator shows a message instead of a number. For shorter adults, the healthy BMI range from the BMI calculator is the better reference.
Is ideal body weight the same as a healthy weight?
Not exactly. These formulas ignore age, muscle mass and body composition, so a muscular person can be healthy well above them. Treat the results as a rough reference, and use body fat percentage, waist size and advice from a doctor or dietitian for personal goals.
Is it safe to enter my height and sex into this calculator?
Yes. The calculator runs in your browser and nothing is uploaded; you can check the Network tab in DevTools. It never asks for your current weight and does not store anything between visits. Reloading the page returns it to the default example.
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