To calculate goal weight from target bmi, multiply the chosen BMI by height in metres squared. For example, a person who is 1.75 m tall and selects a target BMI of 22.5 would get an estimated target weight of about 68.9 kg. This conversion provides a planning reference, not a determination of what someone’s personal or medical goal should be.
Goal weight from target bmi: the formula
The metric formula is:
Goal weight in kilograms = target BMI × height² in metres
Height must be expressed in metres because the standard BMI calculation uses kilograms and metres. If height is recorded in centimetres, divide it by 100 before applying the formula.
For example, 175 cm becomes 1.75 m. Square the height by multiplying it by itself:
1.75 × 1.75 = 3.0625 m²
Then multiply that result by the selected target BMI. The answer is the body weight that corresponds to that BMI at the stated height.
Step-by-step method
- Measure or enter height.
- Convert height to metres if necessary.
- Multiply height in metres by itself.
- Choose a target BMI.
- Multiply the target BMI by height squared.
- Round the final weight to a useful level of precision, such as the nearest 0.1 kg.
If pounds are preferred, the kilogram result can be converted to pounds. Using the unrounded kilogram result before conversion helps reduce small rounding differences. A goal weight calculator can handle these unit conversions automatically.
Worked example for a height of 1.75 m
Consider an adult who is 1.75 m tall and has chosen 22.5 as a planning BMI. The calculation begins by squaring the height:
1.75² = 3.0625
Next, multiply the squared height by the target BMI:
22.5 × 3.0625 = 68.90625 kg
Rounded to one decimal place, the corresponding target weight is 68.9 kg. This means that a weight of approximately 68.9 kg at 1.75 m produces a BMI of about 22.5.
The result is a mathematical conversion rather than a prediction. It does not mean the person will reach that weight, how long a change might take, or whether 22.5 is the most appropriate target for that individual.
Calculating a BMI-based range at the same height
The same method can convert two BMI values into a weight range. According to the US Centers for Disease Control and Prevention, the adult “healthy weight” BMI category runs from 18.5 to 24.9. At 1.75 m, the calculations are:
- Lower reference: 18.5 × 3.0625 = approximately 56.7 kg
- Upper reference: 24.9 × 3.0625 = approximately 76.3 kg
The BMI-based healthy weight range for this height is therefore about 56.7 to 76.3 kg. It is a broad screening reference, not a personalised target range.
How to choose a target BMI
A target BMI is an input selected by the user; it is not calculated from height alone. Some people select a value within an adult BMI category for general planning, while others may use a target discussed with a qualified healthcare professional.
The CDC lists the following BMI categories for adults aged 20 years and older:
| BMI | Adult category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 to 24.9 | Healthy weight |
| 25.0 to 29.9 | Overweight |
| 30.0 or higher | Obesity |
These categories describe BMI, not a complete assessment of health. BMI uses only height and weight, so it does not directly measure body fat, muscle mass, fat distribution or fitness.
There is also no requirement to choose the midpoint of the healthy weight range. For example, 22.5 may be useful in a calculation, but it is not a universal recommendation. Personal priorities, current weight, body composition, medical history and professional guidance may affect how a target is selected.
Adult BMI categories should not be applied to children and teenagers in the same way. Their growth and development require age- and sex-specific assessment methods.
What a goal weight calculator can and cannot tell you
A goal weight calculator performs the BMI-to-weight conversion consistently. It is particularly useful when measurements are entered in centimetres, feet and inches, kilograms or pounds, because manual unit conversion can introduce errors.
What it can tell you
- The estimated weight corresponding to a chosen BMI and height.
- A consistent result based on the standard BMI formula.
- The difference between a current weight and the selected reference weight, if the tool provides that detail.
- BMI-based lower and upper weight references when two target BMI values are entered separately.
What it cannot tell you
- What your personal target weight should be.
- Whether the selected BMI is medically appropriate for you.
- Your body-fat percentage, muscle mass or fat distribution.
- How much of a weight difference relates to fat, muscle, fluid or other tissue.
- How quickly or easily a target might be reached.
- Whether weight change would improve a particular health condition.
The calculator’s result is an estimate produced from entered values. Height and body weight measured with suitable equipment are measurements, while the BMI-based target weight is a calculated reference. Its accuracy also depends on entering height correctly and choosing the intended target BMI.
Using the target weight as a planning reference
A single target weight can be convenient, but it should not imply that only one exact scale reading is acceptable. Body weight can vary over short periods, and rounding alone can create small differences between a manual result and a calculator result.
A range may be more practical than a single number. To create one, choose a lower and upper target BMI and calculate the corresponding weight for each. For a person 1.75 m tall, target BMI values of 21 and 23 would correspond to approximately 64.3 kg and 70.4 kg.
That range still reflects chosen BMI values rather than an individual medical assessment. It simply provides two reference points for planning and progress tracking.
It is also important to keep height fixed when comparing results over time. Entering 1.75 m on one occasion and a rounded or incorrectly converted height on another can change the target weight because height is squared in the formula.
Frequently asked questions
Is goal weight the same as ideal weight?
Not necessarily. A goal weight is a selected planning target. In this calculation, it is the weight corresponding to a chosen BMI, rather than a claim about one ideal weight for a particular person.
Can I calculate target weight in pounds?
Yes. The BMI-to-weight calculation can be completed in kilograms and then converted to pounds. Calculator results may differ slightly from manual results because of unit-conversion precision and rounding.
Why does height have such a large effect on the result?
Height is squared in the BMI formula. As a result, two people with the same target BMI but different heights will have different corresponding weights, and the difference is not simply proportional to height.
Can I use the healthy weight range as my personal target range?
It can serve as a general BMI-based reference for adults, but it does not automatically define an appropriate personal range. BMI categories do not account for muscle mass, body composition, medical history or individual priorities.
Can the formula work backwards from weight to BMI?
Yes. Divide weight in kilograms by height in metres squared. For example, 68.9 kg divided by 3.0625 m² gives a BMI of approximately 22.5.
Why is my manual answer slightly different from the calculator?
Small differences usually result from rounding height, weight or unit conversions at different stages. Keep several decimal places during the calculation and round only the final result.
Key takeaway
The calculation for goal weight from target bmi is straightforward: multiply the selected BMI by height in metres squared. The result is a target weight associated with those two inputs, not a personalised judgment about what someone should weigh.
A BMI-based target or healthy weight range may offer a useful planning reference, but it cannot represent body composition, health history or personal circumstances. Interpret the number as an estimate and keep its limitations in view.