Smart BMI Calculator by Age and Gender
Accurate, fast, and private. Our body mass index calculator helps you track your health journey with precision. Whether you need a BMI calculator kg with age adjustments or standard units, we provide clear insights into your weight category.
- Optimized for Men, Women & Children
- Instant BMI score & visual analysis
- Privacy-focused (data stays on device)
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Why use this BMI Calculator KG with Age tool?
Built with modern standards to provide the most reliable health estimation for every age group.
Age & Gender Smart
Calculate BMI by age and gender. While the formula is standard, we provide context-aware insights for different life stages.
100% Private
We don’t store your weight or height data. All processing happens locally in your browser.
Fully Responsive
Optimized for every screen size, from large desktops to the smallest mobile phones.
How to Use the Calculator
Enter Personal Details
Select gender and input your age to ensure the BMI calculator provides relevant context.
Choose Unit & Measures
Toggle between Metric (cm/kg) or Imperial (ft/lbs) and enter your height and weight.
Get Instant Analysis
Click calculate to see your BMI score, visual position on the gauge, and health category.
BMI Categories
- Underweight < 18.5
- Normal weight 18.5 – 24.9
- Overweight 25.0 – 29.9
- Obesity 30.0 or greater
Frequently Asked Questions
How do I calculate my BMI?
The standard formula for Body Mass Index (BMI) depends on your measurement system:
- Metric: Weight (kg) / [Height (m)]²
- Imperial: 703 × Weight (lbs) / [Height (in)]²
Simply divide your weight by your height squared to get your score.
What is the BMI of 70kg and 165cm?
The BMI is 25.7.
Calculation: 70 ÷ (1.65 × 1.65) = 25.71. This falls into the Overweight category (25.0–29.9).
Is a BMI of 25 chubby?
Not necessarily. A BMI of 25.0 is exactly on the borderline between “Normal” and “Overweight”.
However, BMI is a general screening tool and does not account for muscle mass. An athlete with high muscle density may have a BMI of 25+ without having excess body fat (“chubby”).
How to calculate BMI with age?
For adults (20+), age is not used in the calculation formula itself; the standard weight/height² formula applies to everyone.
For children and teens (2-19), you must use “BMI-for-age” percentile charts. A child’s BMI is compared against others of the same age and gender to determine if they are underweight, healthy, or obese.
What is the BMI of 40 kg and 150 cm?
The BMI is 17.8.
Calculation: 40 ÷ (1.50 × 1.50) = 17.77. This is considered Underweight (below 18.5).
What is a healthy BMI by age?
- Adults (18-65): 18.5 – 24.9
- Older Adults (65+): 25.0 – 27.0 is often considered acceptable to provide a reserve against illness and frailty.
- Children: Varies by specific age month; consult a pediatrician’s growth chart.
What is the correct height and weight for age?
There is no single “correct” weight for an age because height varies significantly between individuals. Instead, doctors look for:
- Adults: A weight that results in a BMI between 18.5 and 24.9.
- Children: Following their personal growth curve consistently on a CDC or WHO growth chart.
What is the BMI of 70 kg 170 cm?
The BMI is 24.2.
Calculation: 70 ÷ (1.70 × 1.70) = 24.22. This falls comfortably within the Normal (Healthy) Weight range.