How to Calculate Appropriate Weight

Three Methods:Body Mass Index CalculationsThe Limitations of BMI CalculationsBody Fat Percentage

Sure, you know your BMI. But shouldn't your number be a little more personalized? The short answer: yes. BMI calculators do have their limits. It's best to know your body's fat percentage, too, if you're looking to stay healthy and disease free.

Method 1
Body Mass Index Calculations

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    Locate a BMI calculator or chart. Many can be found online and most are trustworthy -- it's a simple mathematical equation that is the same across all boards. However, for a more reputable source, the BMI calculator or chart can be found at the U.S. Department of Health & Human Services website or at your local physician's office.
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    Enter your height and weight. Most calculators have options for both standard and metric measurements. You'll also need to report your gender into the BMI calculator for more accurate results.
    • You can do it manually, if you so choose. For standard measurements:
      • Take your height in inches and square it. If you are 70 inches (177.8 cm) tall, take 70 x 70.
      • Take your weight divided by that number. If you are 150 pounds, that's 150/4900. That's .0306.
      • Then, take that number and times it by 703. There's your BMI. For this instance, that's 21.6.
    • For metric measurements:
      • Square your height. If you are 1.77 meters (5.8 ft) tall, that's 1.77 x 1.77. In other words, 3.13.
      • Divide your weight by that number. If you're 68 kilograms, that 68 divided by 3.13, or 21.6. Your BMI.
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    Find your BMI on the results chart. There are four categories: underweight, normal weight, overweight, and obese. Remember, these are general guidelines.
    • You are underweight if the index results are under 18.5.
    • You are at your target weight if you the index results are between 18.5 and 24.9.
    • You are considered overweight if your index results are between 25 and 29.9.
    • You are considered obese if you have a BMI of 30 or greater.
      • Your risk for certain diseases, such as type 2 diabetes, heart disease, high blood pressure and certain cancers increases with your BMI.

Method 2
The Limitations of BMI Calculations

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    Know that BMI calculators do not work for children. Assess the weight of children and teens by using a BMI Calculator specifically designed for younger age groups. The Children's BMI uses height and weight measurements, gender, date of birth and date of measurements to perform weight assessment calculations.
    • Children measuring at the 5th percentile or lower are deemed underweight.[1]
    • Children measuring between the 5th and 84th percentile are considered at a healthy weight[1]
    • Children measuring between the 85th and 94th percentile are deemed overweight.[1]
    • Children measuring equal to or greater than the 95th percentile are considered obese.[1]
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    Know that BMI calculators do not work for the elderly or serious athletes. These calculators do not take into account bone density, muscle mass, or fat proportion.
    • It may overestimate body fat in athletes and others who have a muscular build. On the flip side, it may underestimate body fat in older persons and others who have lost muscle.

Method 3
Body Fat Percentage

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    Measure your waist circumference. In addition to your BMI, knowing this number will help you to assess your weight and risk of developing obesity-related health conditions. Excessive waist fat increases risk for Type 2 diabetes, high cholesterol, high triglycerides, high blood pressure and coronary artery disease.
    • Measure your waist size by holding a cloth tape measure around your waist, just above your hip bone and measuring the number of inches or centimeters. The tape should be snug, but not pushing into your skin.
    • A man's waist should be 40 inches (101.6 cm) or less.
    • A woman's waist should be 35 inches (88.9 cm) or less.
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    Find a body fat percentage calculator. Numerous ones are available online and they take into account your waistline in addition to your height, weight, and sex. They're not completely accurate, but they will give you a ballpark.
    • For men, lean is considered 15-18% body fat. Moderate is 19-24%.
    • For women, lean is considered 21-25%. Moderate is 26-29%.
      • Overweight is anything above these numbers.
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    See your doctor for a skinfold test. If you're very hard up, skin calipers can be bought online. But it's best to address any questions or concerns about your assessment with a health care professional.
    • The skin caliper test is much more accurate. It gives an indication of body composition (muscle and fat). It's important because two people with the same body weight and height could have completely different body composition. Different results lead to different ways to stay or become healthy.


  • Consult your physician to develop a diet and exercise plan if you are overweight or underweight. Never become obsessed with a number you received offline.


  • BMI is a useful screening tool, but should not be considered diagnostic. A health care provider should be consulted for weight assessments meant to measure any health or risk concerns.

Things You'll Need

  • BMI calculator or chart
  • Measuring tape
  • Body fat calculator

Article Info

Categories: Losing Weight