What this calculator does
The Target Weight for BMI Calculator tells you exactly how much you should weigh to hit a chosen Body Mass Index (BMI). Because BMI depends only on height and weight, once you fix your height and a goal BMI you can solve directly for the weight that produces it. The tool also shows your current BMI and how many kilograms you need to lose (or gain) to get there.
How to use it
Enter your current weight in kilograms, your height in centimetres, and the BMI you want to reach. A target BMI of 18.5–24.9 is considered the "normal" range for most adults. The calculator converts your height to metres, computes the target weight, and compares it with your current weight.
The formula explained
BMI is defined as weight in kilograms divided by height in metres squared: \(\text{BMI} = W / h^{2}\). Rearranging for weight gives \(W = \text{BMI} \times h^{2}\). So the target weight is simply your goal BMI multiplied by your height (in metres) squared. The amount to lose is your current weight minus that target weight; a negative result means you would need to gain weight.
$$\text{Target Weight} = \text{Target BMI} \times \left(\frac{\text{Height (cm)}}{100}\right)^{2}$$
Worked example
Suppose you weigh 60 kg, are 170 cm tall, and want a BMI of 22. Height in metres is 1.70, so \(h^{2} = 2.89\). Target weight = \(22 \times 2.89 = 63.58\) kg. Weight to lose = \(60 - 63.58 = -3.58\) kg, meaning you would actually need to gain about 3.58 kg. Your current BMI is \(60 / 2.89 \approx 20.76\).
FAQ
Is BMI accurate for everyone? BMI is a population-level screening tool and does not account for muscle mass, bone density, age or sex, so very muscular people may read as "overweight." Use it as a guide, not a diagnosis.
What BMI should I target? Most health bodies use 18.5–24.9 as the healthy range. Choose a value within that band unless advised otherwise by a clinician.
Why is my result negative? A negative "weight to lose" means your current weight is below the target weight, so to reach that BMI you would need to gain weight.
