BMI Weight Loss
Calculate your BMI, BMI Prime, target weight based on your desired BMI, and how much weight to lose or gain. Free online body mass index weight loss tracker with charts.
About This Calculator
The BMI Weight Loss Calculator helps you determine your current body mass index (BMI), understand what BMI category you fall into, and calculate how much weight you need to lose or gain to reach your target BMI. Whether your goal is achieving a healthy BMI of 21.7 or reaching the upper end of the normal range at 24.9, this tool provides your specific target weight and the exact weight change needed.
BMI is calculated using the standard formula: BMI = weight (kg) / height (m)2. For example, a person weighing 70 kg with a height of 170 cm has a BMI of 24.2. The calculator also computes BMI Prime, which is your BMI divided by 25 (the upper limit of the healthy range). A BMI Prime of 1 or less indicates a healthy weight status.
The healthy weight range corresponds to a BMI of 18.5 to 24.9. Your target weight for any given BMI is calculated as: target weight (kg) = target BMI × height (m)2. The weight change needed is simply the difference between your current weight and your target weight.
Regional Notes
India: The WHO BMI cutoffs are used globally, but research suggests that Asian populations may have higher health risks at lower BMI levels. Some Indian health organizations recommend a lower normal BMI range of 18.5–23 for Asian Indians. The target BMI of 21.7 is recommended by many Indian health experts as the ideal BMI for Asian Indians.
United States: The CDC and NIH use the standard WHO BMI categories (underweight <18.5, normal 18.5–24.9, overweight 25–29.9, obese ≥30). BMI is widely used in clinical settings for weight management and health risk assessment, though it is not a diagnostic tool for individual body fat percentage.
United Kingdom: The NHS uses the same WHO BMI categories and recommends maintaining a BMI between 18.5 and 24.9. The NHS Weight Loss Plan provides structured guidance for achieving a healthy BMI through diet and exercise. BMI measurements are routinely taken during NHS Health Checks for adults aged 40–74.
Frequently Asked Questions
How does the BMI Weight Loss calculator work?
Enter your weight in kg, height in cm, and target BMI. The calculator computes your current BMI using the formula BMI = weight(kg) / height(m)², then calculates the target weight needed to reach your goal BMI and the difference from your current weight.
What is a healthy BMI range?
A healthy BMI range is between 18.5 and 24.9 for most adults. Below 18.5 is considered underweight, 25–29.9 is overweight, and 30 or above is obese. The ideal target BMI is often around 21–22.
What is BMI Prime?
BMI Prime is the ratio of your actual BMI to the upper limit of the healthy BMI range (25). A BMI Prime of 1 or less means you are within the healthy weight range. A BMI Prime greater than 1 indicates you are overweight.
How much weight do I need to lose to reach a healthy BMI?
The calculator shows your target weight for your chosen BMI and the weight change needed. For a BMI of 21.7 at 170 cm height, the target weight is 62.7 kg. The difference between your current weight and this target tells you how much to lose or gain.
Is BMI accurate for athletes and muscular people?
BMI may overestimate body fat in athletes and people with high muscle mass since it does not distinguish between muscle and fat. Athletes should consider body fat percentage measurements alongside BMI for a more accurate health assessment.
What is the formula for calculating BMI?
BMI is calculated using the formula: BMI = weight in kilograms divided by height in meters squared (BMI = kg/m²). For example, a person weighing 70 kg with a height of 170 cm has a BMI of 70 / (1.7 × 1.7) = 24.2.
Is the BMI calculation different for men and women?
The BMI formula is the same for men and women, but the interpretation can differ. Women naturally have a higher body fat percentage, so the healthy BMI range is adjusted through BMI Prime and body composition analysis for a more accurate assessment.
How can I lose weight to reach my target BMI?
Create a calorie deficit by reducing daily calorie intake by 300–500 calories and increasing physical activity. A sustainable weight loss rate is 0.5–1 kg per week. Combine a balanced diet with regular exercise including cardio and strength training for best results.