Healthy Weight Calculator

How a healthy weight range is calculated

Health organisations define a healthy weight as the range in which body mass index (BMI) falls between 18.5 and 25 (the World Health Organization's "normal" band runs from 18.5 to 24.9). BMI is weight divided by height squared, so for any height there is a lowest and a highest weight that keep BMI inside the band. Those two weights are what this calculator reports.

weight (kg) = BMI × height (m)²Evaluated once with BMI = 18.5 for the lower limit and once with BMI = 25 for the upper limit.

weight (lb) = BMI × height (in)² ÷ 703The same relation in US units.

Both limits are rounded to the nearest whole pound or kilogram.

Using the calculator

1. Choose US units or Metric units.
2. Enter your height. In US units, feet and inches are separate boxes and either can be left blank. In metric units choose centimetres or metres.
3. Press Calculate to see the range. A height of zero or a blank field gives no result.

The calculator does not ask for your weight. To see where your current weight sits, compare it with the range or use the BMI calculator.

Worked example

Someone who is 175 cm tall has a height of 1.75 m, and 1.75² = 3.0625. Multiply by the two BMI limits:

18.5 × 3.0625 = 56.7 kg and 25 × 3.0625 = 76.6 kg

The calculator displays this as 57 - 77 kg. A person of this height who weighs 80 kg has a BMI of 80 ÷ 3.0625 ≈ 26.1, which is about 3.4 kg above the upper limit.

In US units, 5 ft 10 in is 70 inches. The lower limit is 18.5 × 70² ÷ 703 ≈ 128.9 lb and the upper limit is 25 × 70² ÷ 703 ≈ 174.3 lb, shown as 129 - 174 lb.

Healthy weight by height

The two columns are independent: the metric and US rows are not exact equivalents of each other, only typical heights in each system.

Why a healthy weight matters

Large studies consistently link BMI above the healthy band with higher rates of type 2 diabetes, high blood pressure, heart disease, some cancers, sleep apnoea and joint problems. Risk generally rises gradually rather than switching on at a threshold. Being underweight also carries risks, including nutritional deficiency, reduced bone density, weakened immunity and, in older adults, frailty.

For people who are above the range, losing even 5 to 10 percent of body weight is often enough to improve blood pressure, blood sugar and cholesterol, so a modest first target can be more useful than the far end of the range. The weight loss calorie calculator and calorie calculator can help you plan the energy side of that.

This calculator gives a general range, not a diagnosis or a personal goal. Speak to a doctor or dietitian about the weight that is right for you. See the disclaimer.

What the range does not tell you

• Muscle versus fat. BMI cannot tell them apart, so a muscular athlete may land above the band while carrying little fat. A body fat calculator gives a different view.
• Fat distribution. Fat around the waist carries more risk than fat on the hips and thighs, and BMI does not capture it.
• Ethnicity. Health risks begin at lower BMI values in several Asian populations, and some agencies use lower cut-offs for them.
• Age and growth. The band is for adults. Children and teenagers are assessed against growth charts by age and sex, and very old adults may be healthier at slightly higher BMI values.
• Pregnancy. Weight guidance during pregnancy is different and should come from a midwife or doctor.

Other estimates, such as the ideal weight calculator, use different formulas and return a single figure instead of a band, so they will not match this range exactly.