Backwards BMI Calculator (Reverse BMI)
Know your height and target BMI, but not your target weight? This calculator works backwards from BMI to estimate the body weight that matches your chosen BMI.
Tip: You can also use BMI 18.5–24.9 to estimate a typical "healthy weight range" for your height.
What is a backwards BMI calculator?
A standard BMI calculator takes your height and weight, then outputs a BMI score. A backwards BMI calculator does the reverse: it starts with your height and desired BMI, then estimates your corresponding weight. This is useful when setting practical goals such as, “What weight would put me at BMI 23?”
The reverse BMI formula
BMI is defined as:
BMI = weight (kg) / height (m)2
To solve for weight, rearrange the equation:
weight (kg) = BMI × height (m)2
That single equation powers this calculator. For imperial users, the tool converts feet/inches to meters and pounds to kilograms behind the scenes.
How to use this calculator effectively
1) Pick your unit system
Choose metric if you think in centimeters and kilograms, or imperial if you use feet/inches and pounds.
2) Enter accurate height
Height errors have a big impact on BMI-based estimates. A small height mistake can shift target weight by several pounds.
3) Set a realistic target BMI
- 18.5 to 24.9 is commonly considered a normal BMI range for adults.
- Some people target the middle of that range, such as BMI 21–23.
- Athletes and muscular individuals may not fit BMI conventions perfectly.
4) Add current weight (optional)
If you include current weight, the calculator shows the difference between your present weight and your target weight, plus your current BMI category.
Interpreting your result
Your target weight is an estimate, not a diagnosis. Use it as a planning number. If your current weight is above target, think in terms of gradual progress. If below target, focus on healthy gain with strength and adequate nutrition.
A practical pace for most adults is steady and sustainable behavior change rather than aggressive short-term dieting.
Why this can be helpful for goal setting
- Clarity: Converts an abstract BMI number into a concrete weight goal.
- Planning: Lets you set milestones (for example, every 5 lb or 2 kg).
- Tracking: You can revisit the same target and monitor trends over time.
- Motivation: Seeing progress toward a clearly defined number can improve consistency.
Limitations of BMI (important)
BMI is a screening tool, not a direct measure of body fat, health, or fitness. It does not account for body composition, fat distribution, age-related changes, or ethnicity-specific differences in health risk. Someone with high muscle mass may appear “overweight” by BMI despite excellent health markers.
For a fuller picture, combine BMI with waist circumference, blood pressure, blood glucose, lipid profile, sleep quality, activity level, and how you feel day to day.
Bottom line
A backwards BMI calculator is a fast way to estimate target weight from height and BMI. It is excellent for rough planning and progress tracking, especially when paired with healthy habits: balanced nutrition, resistance training, regular movement, stress management, and sleep.
For personalized targets, especially if you have medical conditions or a history of disordered eating, talk to a qualified healthcare professional.