Your weight depends on many different factors — everything from what you eat to how much you move to your environment and genetics. It’s important to set goals when you want your current weight to change — but you first need to know your target weight.

It’s easy to figure out how much you should weigh from a health perspective. From there, you can determine how much you might need to lose (or gain) to reach a healthier weight.

Why does your weight matter?

You might look and feel fine regardless of what you weigh. That doesn’t necessarily mean you’re healthy, though. It’s important to look at health in the long term to determine whether or not you’re at risk for disease later in life based on your condition now. The Nutrition Source says your weight can put you at risk for a long list of conditions. If you don’t start taking care of yourself now — no matter how young or old you are — there will be consequences.

Your ideal weight

Your ideal body weight is just a general marker of how close you are to what is considered a healthy weight. The math for this one is simple. Here’s how to calculate your own body weight, according to the American Journal of Clinical Nutrition.

Females: Start with 100 pounds for the first five feet of your height. Add five additional pounds for every inch over five feet to reach your ideal weight.

A 5’5” female should ideally weigh 125 pounds. Her acceptable weight range is 115 – 135.

Males: Start with 106 pounds for the first five feet of your height. Add six additional pounds for every inch over five feet to reach your ideal weight.

A 5’5” male should ideally weigh 136 pounds. His acceptable weight range is 126 – 146.

Your weight as you age

Age usually doesn’t matter when determining your ideal healthy weight. Livestrong.com suggests using body fat percentage to make sure you’re on the right track — or you’re on your way to getting there. Nerd Fitness provides a helpful chart to help you determine what your ideal body fat percentage is based on your gender and activity level. Measuring tape and a few calculations can help you figure out how much body fat you’re actually carrying around.

Your weight and disease risk

The more you weigh, the more at risk you are for a number of potentially fatal conditions and diseases. According to the National Heart, Blood, and Lung Institute, carrying around excess body fat — especially around your waist — puts you at greater risk for heart disease and Type 2 diabetes. Being overweight or obese increases your blood pressure, affects your breathing, and also increases your risk for developing certain cancers. Losing weight significantly decreases your risk for these conditions.

How to get to (and maintain) a healthy weight

Once you know how much you should weigh, you can decide what you need to start doing to make positive lifestyle changes. Both diet and exercise are equally important when it comes to weight loss. Everyone is different, so you can only count on the habits and strategies that are most effective for you personally. These are the healthiest ways to lose weight fast.

What about BMI?

Your body mass index measures whether or not you have a healthy body fat percentage at your present height and weight. BMI is the same for both males and females at any age. The math:

Your weight in pounds x 0.45 = your weight in kilograms

Your height in inches x 0.025 = height in meters

Square that, then divide your weight in kilograms by your height in meters.

Example BMI calculation — and what it means

Let’s say you are 5’5” and weigh 150 pounds.

(150 x 0.45) / (65 x 0.025) = (67.5) / (1.625 x 1.625) = (67.5 / 2.64) = BMI = 25

Of course, you can also use Mayo Clinic’s BMI calculator, which takes your age and gender into account to assess your health status.

A healthy BMI ranges from 19 to 25. Technically, a BMI above (25.6) is at the very low end of the overweight category. At a BMI over 30, a person is considered obese.

Unfortunately, the reason many professionals are moving away from using BMI is that it doesn’t take muscle mass or age into consideration. Older adults, for example, might not be considered healthy at what is considered to be a normal BMI.