What is BMI?

BMI (Body Mass Index) is a numerical value calculated from a person's weight and height. It's a simple screening tool used to categorize individuals as underweight, normal weight, overweight, or obese based on their body mass relative to their height.

How BMI Is Calculated:

• Metric Formula: BMI = weight(kg) / height²(m²)

• Imperial Formula: BMI = 703 × weight(lb) / height²(in²)

BMI Categories:

• Underweight: BMI less than 18.5

• Normal weight: BMI between 18.5 and 24.9

• Overweight: BMI between 25 and 29.9

• Obesity: BMI 30 or greater

Purpose and Uses:

• Quick assessment of weight status

• Population-level health screening

• Statistical tool for tracking weight trends

• Initial assessment in healthcare settings

Limitations:

• Doesn't differentiate between muscle and fat

• Doesn't account for body composition

• May not be accurate for athletes, elderly, pregnant women, or certain ethnic groups

• Doesn't measure or account for fat distribution

BMI is best used as one of several tools to assess overall health rather than as a standalone diagnostic tool. Healthcare providers typically consider other factors like waist circumference, blood pressure, cholesterol levels, and family history when evaluating an individual's health status.

Empowering Your Health Journey

At My Free BMI, we provide a simple, effective tool to calculate your body mass index and understand its implications for your health and wellness.

3 Tips to Maintain a Normal BMI

Easily understand your health with our simple BMI calculator and informative resources.

1. Regular Exercise

Aim for at least 150 minutes of moderate aerobic activity or 75 minutes of vigorous activity weekly, plus muscle-strengthening exercises twice a week. Find activities you enjoy—walking, swimming, cycling, or team sports—to make exercise sustainable. Even short, frequent movement breaks throughout the day can boost metabolism and prevent weight gain.

2. Balanced Diet

Focus on nutrient-dense whole foods while controlling portion sizes. Include plenty of vegetables, fruits, lean proteins, whole grains, and healthy fats in your meals. Limit processed foods, added sugars, and excessive carbohydrates. Consider meal planning to avoid impulsive food choices, and practice mindful eating by paying attention to hunger and fullness cues.

3. Proper Hydration

Drink adequate water throughout the day—generally 8-10 cups (64-80 oz) for most adults. Water supports metabolism, helps control appetite (as thirst is often mistaken for hunger), and assists with digestion. Replace sugary beverages with water, herbal teas, or infused water to reduce empty calories. Establishing a hydration routine, such as drinking a glass of water before meals, can help maintain consistent intake.