By Zencalcy Editorial TeamLast reviewed About us
This calculator converts a target BMI into a target body weight for your height, then shows the difference from your current weight. It is a planning aid: the number tells you what the scale would need to read for a given BMI, not how quickly or safely to get there. Sustainable loss is usually gradual, and the target should fit your health history.
Find the weight change needed to reach a target BMI.
| The top of the WHO healthy range is 24.9. |
Target weight = target BMI × height(m)² Weight change = current weight − target weight
A target BMI of 24.9 sits at the upper edge of the healthy adult band. The calculation assumes weight change comes entirely from fat, which is not true in practice: water, glycogen and lean mass also change. For people with obesity, even a 5–10% loss can improve metabolic markers before BMI reaches the healthy band.
| Symbol | Meaning |
|---|---|
| Target BMI | The BMI you want to plan around, usually 18.5–24.9. |
| Target weight | Weight that corresponds to the target BMI at your height. |
| Weight change | Current weight minus target weight; positive means loss. |
Target weight = 24.9 × 1.75² = 76.3 kg. Current BMI is 90 ÷ 1.75² = 29.4, so the plan involves losing 90 − 76.3 = 13.7 kg. At a sustainable 0.5 kg per week that is roughly 27 weeks, before plateaus and normal fluctuation.
The arithmetic is the easy part. The harder question is how to close the gap without triggering rebound loss of lean mass. A modest energy deficit, adequate protein and resistance training help preserve muscle while fat comes down. Weight loss also slows as body mass falls, so a linear projection from week one will overpromise. Plan checkpoints rather than a single deadline: review the monthly trend, adjust intake if the average has not moved for three or four weeks, and protect sleep and recovery. If the gap to your target is large, consider an intermediate goal such as five percent of body weight, which is enough to improve blood pressure and glucose in many people. Finally, decide in advance what maintenance looks like. Reaching a BMI number is not the end of the process; keeping it is a separate skill.
Continue with the BMI Calculator for Men, BMI Calculator for Women, or the Geriatric BMI Calculator — or browse more bmi tools and all health calculators.
Also see the BMI Calculator.
For most adults the WHO healthy band is 18.5–24.9, but an individual target should account for age, muscle mass, pregnancy, illness and ethnicity. A clinician can help set a range that is realistic for you.
BMI is a screening ratio, not a diagnosis. The adult WHO cutoffs do not account for muscle mass, fat distribution, ethnicity or age. Pregnant people and children need different references. Interpret the result alongside waist circumference, medical history and other measurements.
Reference material used to build and check this calculator:
Last reviewed: September 2026. See how we build and check every tool on the about page.
Content updated: September 2026