How to Calculate Weight from BMI and Height
Use our reverse BMI calculator to determine your target weight based on Body Mass Index and height specifications.
Metric (kg, cm)
Imperial (lbs, ft/in)
Choose your preferred unit system.
Enter height in centimeters.
Please enter a valid height (50-300 cm).
Enter height in feet and inches.
Please enter a valid height.
The Body Mass Index you wish to solve for (Standard Healthy: 18.5 – 24.9).
Please enter a valid BMI (10-60).
Calculated Weight
67.4
kg
Formula Used: Weight = BMI × (Height)²
Using 22 × (1.75m)²
Using 22 × (1.75m)²
Healthy Weight Min (BMI 18.5)
56.7 kg
Healthy Weight Max (BMI 24.9)
76.3 kg
Classification
Normal Weight
Visual representation of weight ranges for your height.
What is how to calculate weight from bmi and height?
Understanding how to calculate weight from bmi and height is a critical skill for health professionals, fitness enthusiasts, and anyone setting personal health goals. While most people are familiar with calculating BMI (Body Mass Index) to check if they are in a healthy range, the reverse calculation is equally valuable.
This process allows you to determine a specific target weight (in kilograms or pounds) that corresponds to a desired BMI value. Instead of guessing what your ideal weight should be, you can use the mathematical relationship between mass and height to derive a precise figure. This is particularly useful for setting realistic weight loss or weight gain targets based on medical recommendations.
Common misconceptions include the idea that this calculation accounts for muscle mass or body composition. It is important to remember that while the math is precise, BMI itself is a general screening tool that does not differentiate between fat and muscle. Therefore, knowing how to calculate weight from bmi and height gives you a "scale weight" target, but should be used in conjunction with other health metrics.
Formula and Mathematical Explanation
To master how to calculate weight from bmi and height, one must first understand the standard BMI formula. The standard formula is defined as weight divided by the square of height.
Standard BMI Formula: $$ BMI = \frac{Weight}{Height^2} $$
To find the weight, we rearrange this equation algebraically. The reverse formula becomes:
Weight = BMI × (Height)²
Variable Breakdown
| Variable | Meaning | Metric Unit | Imperial Note |
|---|---|---|---|
| Weight | Body Mass | Kilograms (kg) | Convert to lbs after calculation |
| BMI | Body Mass Index | kg/m² | Unitless index |
| Height | Stature | Meters (m) | Must convert cm or inches to meters first |
Note: If you are using Imperial units (pounds and inches), the standard BMI formula includes a conversion factor of 703. Therefore, the reverse calculation for pounds is: Weight (lbs) = (BMI × Height(in)²) / 703.
Practical Examples (Real-World Use Cases)
Example 1: Setting a Healthy Target
John is 1.80 meters tall (approx 5'11") and wants to know what he would weigh at a BMI of 22 (the middle of the healthy range). He wants to learn how to calculate weight from bmi and height to set his gym goal.
- Height: 1.80 m
- Target BMI: 22
- Calculation: Weight = 22 × (1.80)²
- Step 1: 1.80 × 1.80 = 3.24
- Step 2: 22 × 3.24 = 71.28
- Result: John's target weight is 71.28 kg.
Example 2: Medical Threshold Calculation
Sarah is 64 inches tall (5'4″). Her doctor advises her that she needs to reach a BMI of 24.9 to be considered within the "Normal" category. She needs the result in pounds.
- Height: 64 inches
- Target BMI: 24.9
- Formula (Imperial): Weight = (BMI × Height²) / 703
- Calculation: (24.9 × 64²) / 703
- Step 1: 64 × 64 = 4,096
- Step 2: 24.9 × 4,096 = 101,990.4
- Step 3: 101,990.4 / 703 = 145.07
- Result: Sarah needs to reach approximately 145 lbs.
How to Use This Calculator
Our tool simplifies the math involved in how to calculate weight from bmi and height. Follow these steps for accurate results:
- Select Unit System: Choose between Metric (kg/cm) or Imperial (lbs/ft/in) using the dropdown menu.
- Enter Height: Input your accurate height. If using imperial, ensure you split feet and inches correctly (e.g., 5 ft 10 in).
- Enter Target BMI: Input the BMI value you wish to solve for. Common targets are 22 (ideal median) or 25 (overweight threshold).
- Review Results: The calculator instantly displays the specific weight required to achieve that BMI.
- Analyze the Chart: Look at the visual bar chart to see where your calculated weight falls relative to the underweight, normal, and overweight categories.
Key Factors That Affect Results
When studying how to calculate weight from bmi and height, several external factors influence how you should interpret the data:
- Muscle Mass Density: Muscle is denser than fat. A bodybuilder calculating weight from a BMI of 25 will look very different from a sedentary person at the same weight.
- Bone Structure: Individuals with larger skeletal frames may naturally weigh more at the same BMI, making standard BMI charts slightly less applicable.
- Age and Metabolism: While the math doesn't change with age, acceptable BMI ranges can shift. Older adults are often advised to maintain a slightly higher BMI to protect against frailty.
- Hydration Levels: Your daily weight can fluctuate by several pounds due to water retention, affecting how close you are to your calculated target on any given day.
- Gender Differences: Men and women typically have different body fat distributions. Two people of different genders calculating the same weight from the same BMI may have different health profiles.
- Height Measurement Accuracy: Since height is squared in the formula, even a small error in measuring height (e.g., 2cm) can lead to a significant discrepancy in the calculated target weight.
Frequently Asked Questions (FAQ)
Is the formula for how to calculate weight from bmi and height the same for men and women?
Yes, the mathematical formula is identical for adult men and women. However, the interpretation of "healthy" BMI ranges can vary slightly based on body composition guidelines.
Can I use this calculation for children?
No. For children and teens, BMI is age-and-gender percentile-based. The standard reverse calculation formula used here applies primarily to adults (age 20+).
What is a good target BMI to use?
For most adults, a BMI between 18.5 and 24.9 is considered the "healthy weight" range. A BMI of 22 is often used as a median target when learning how to calculate weight from bmi and height.
Why does the calculator show a range?
Health is not a single number. The tool provides a range (e.g., min and max healthy weight) because maintaining a precise single poundage is unrealistic and unnecessary for good health.
Does this calculation account for body fat percentage?
No. This is a strictly mathematical derivation of weight based on height and BMI. It does not distinguish between lean mass and fat mass.
How often should I recalculate?
You only need to recalculate if your height changes (rare for adults) or if your target BMI goal changes based on doctor recommendations.
Is it possible to have a high BMI but be healthy?
Yes, athletes with high muscle mass may have a BMI in the "overweight" category (25-30) despite having low body fat and excellent metabolic health.
Why use BMI instead of just weight?
BMI normalizes weight for height, allowing for a standardized comparison of health risks across populations of different sizes.
Related Tools and Internal Resources
Enhance your health planning with our other specialized calculators:
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Standard BMI Calculator
Calculate your current Body Mass Index to see where you stand today.
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Ideal Body Weight Calculator
Find your ideal weight using formulas like Devine, Robinson, and Miller.
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Calorie Deficit Calculator
Determine how many calories you should eat to reach your calculated weight.
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Body Fat Percentage Calculator
Go beyond BMI by estimating your body composition.
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Basal Metabolic Rate (BMR)
Calculate the energy your body burns at rest to optimize your diet.
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Weight Loss Planner
Create a timeline to safely reach the weight calculated above.