There’s no single number that qualifies as your ideal weight. The honest answer depends on your height, your body composition, your age, and how your weight is distributed across your frame. But there are several reliable ways to estimate a healthy range, and understanding how they work helps you figure out where you personally should land.
The BMI Starting Point
Body mass index is the most widely used screening tool. It divides your weight in kilograms by your height in meters squared. The CDC defines a healthy weight as a BMI between 18.5 and 24.9. Below 18.5 is underweight, 25 to 29.9 is overweight, and 30 or above falls into obesity categories.
To put that in practical terms: a person who is 5’6″ has a healthy BMI range of roughly 115 to 154 pounds. A person who is 5’10” falls in the healthy range at about 129 to 174 pounds. That’s a wide spread, which is part of the point. “Ideal” isn’t one number.
BMI has a well-known blind spot, though. It can’t distinguish between muscle and fat. A cubic inch of muscle is denser than a cubic inch of fat, so athletic, muscular people often get classified as overweight or obese even when their body fat is low. On the flip side, someone with little muscle mass and a higher percentage of body fat can have a “normal” BMI while still carrying metabolically risky weight. BMI also doesn’t account for differences in bone density, sex, or ethnic background.
Clinical Formulas for Ideal Body Weight
Doctors and pharmacists sometimes use formulas that estimate ideal body weight based purely on height and sex. These were originally developed for medication dosing, not lifestyle guidance, but they give you a useful midpoint to anchor your expectations.
The most common is the Devine formula. For men, it starts at 110 pounds (50 kg) for a height of 5 feet and adds about 5 pounds (2.3 kg) for every inch above that. For women, it starts at 100 pounds (45.5 kg) at 5 feet and adds the same 5 pounds per inch. So a 5’7″ woman would have an estimated ideal weight of about 135 pounds, and a 5’10” man would land around 166 pounds.
Other formulas give slightly different results. The Robinson formula produces a somewhat higher estimate for women (starting at 108 pounds at 5 feet, adding about 3.7 pounds per inch) and a similar one for men. The Miller formula starts higher still, at about 117 pounds for women and 124 pounds for men at 5 feet, but adds less per inch. The fact that these formulas disagree with each other reinforces the idea that “ideal weight” is a range, not a precise target.
Why Body Fat Percentage Matters More
What actually affects your health isn’t how much you weigh but how much of that weight is fat versus lean tissue. A 2025 study using US national survey data defined overweight as a body fat percentage of at least 25% for men and 36% for women. Obesity was defined as 30% body fat or more for men and 42% or more for women. Those thresholds are quite different from what BMI alone would suggest for many people.
You can get a rough estimate of body fat from a scale with bioelectrical impedance (common in home “smart” scales), though these aren’t highly accurate. More reliable methods include DEXA scans and hydrostatic weighing, which your doctor or a sports medicine clinic can arrange. If your body fat percentage falls in a healthy range for your age and sex, your weight is likely fine regardless of what a BMI chart says.
The Waist Measurements That Predict Risk
Where your body stores fat turns out to be at least as important as how much fat you carry. Fat concentrated around the abdomen, surrounding your internal organs, is more metabolically active and more strongly linked to heart disease, type 2 diabetes, and other chronic conditions than fat stored in the hips and thighs.
Two simple measurements capture this. The first is your waist-to-height ratio. The NHS recommends keeping your waist circumference to less than half your height. If you’re 5’8″ (68 inches), that means a waist below 34 inches. This single check is surprisingly powerful as a health indicator and requires nothing more than a tape measure.
The second is waist-to-hip ratio. For men, a ratio below 0.95 is considered healthy, according to Harvard Health. You calculate it by dividing your waist measurement (at the narrowest point above your navel) by your hip measurement (at the widest point). For a man with a 36-inch waist and 40-inch hips, that’s 0.90, which falls in the healthy zone.
The Risks of Being Too Light
Most people searching for their ideal weight are thinking about losing weight, but it’s worth knowing that being underweight carries real risks too. A large UK study of 3.6 million adults found that underweight men (BMI below 18.5) had a life expectancy from age 40 that was 4.3 years shorter than men at a healthy weight. For underweight women, the gap was 4.5 years. Those numbers are comparable to the life-expectancy reductions seen in obesity.
Underweight can reflect inadequate nutrition, loss of bone density, reduced muscle mass, or an underlying medical condition. If your weight falls below the healthy BMI range and you haven’t intentionally been restricting food, it’s worth investigating why.
How to Find Your Personal Target
Rather than fixating on a single number, use multiple signals together. Start with the BMI healthy range for your height to get a broad window. Then narrow it by considering your frame size, muscle mass, and activity level. A recreational athlete with visible muscle definition might sit at the higher end of that range and be perfectly healthy. Someone with a sedentary lifestyle and little muscle mass might need to aim for the lower end.
Layer in a waist measurement. If your waist is under half your height, that’s a strong sign your weight distribution is working in your favor, even if your scale number feels high. If your waist exceeds that threshold, losing even a small amount of abdominal fat can meaningfully reduce your risk for metabolic disease.
Finally, pay attention to functional markers. Can you climb stairs without getting winded? Is your blood pressure in a normal range? Are your blood sugar and cholesterol where they should be? These metabolic indicators often tell you more about whether your weight is “ideal” than any formula can. Two people at the same height and weight can have very different health profiles depending on their fitness, diet, sleep, and stress levels. Your ideal weight is the one where your body works well, your energy is steady, and your health markers are solid.