There’s no single number that works for everyone. Your ideal body weight depends on your height, sex, age, muscle mass, and body composition. The most common starting point is BMI (body mass index), which puts a “healthy weight” range at a BMI of 18.5 to 24.9. For a 5’8″ person, that translates to roughly 125 to 163 pounds. But BMI is just one lens, and sometimes not the best one. A fuller picture comes from combining it with waist measurements, body fat percentage, and how your body actually functions.
BMI: A Quick Starting Point
BMI divides your weight in kilograms by your height in meters squared. The CDC uses these categories for adults 20 and older:
- Underweight: below 18.5
- Healthy weight: 18.5 to 24.9
- Overweight: 25 to 29.9
- Obesity (Class 1): 30 to 34.9
- Obesity (Class 2): 35 to 39.9
- Severe obesity (Class 3): 40 or higher
To get a ballpark “ideal” weight from your height alone, a formula originally designed for clinical use works like this: women start at about 100 pounds for 5 feet tall and add roughly 5 pounds per inch above that. Men start at about 110 pounds for 5 feet and add the same 5 pounds per inch. So a 5’6″ woman lands around 130 pounds, and a 5’10” man around 160 pounds. These numbers assume an average frame, though, so they can miss the mark for people who are naturally broad or narrow.
BMI’s biggest weakness is that it can’t tell the difference between muscle and fat. A muscular person who lifts weights regularly may have a BMI of 27 and be in excellent health, while someone with the same BMI who carries most of their weight around the midsection faces real metabolic risk. That’s why looking beyond the scale matters.
Where You Carry Weight Matters More Than You Think
Fat stored around your organs (visceral fat) raises your risk of heart disease, type 2 diabetes, and stroke far more than fat stored under the skin on your hips or thighs. Two people at the same weight can have very different health outlooks depending on where that weight sits.
The simplest way to check is the waist-to-height ratio. The NHS recommends keeping your waist measurement below half your height. If you’re 5’8″ (68 inches), that means a waist under 34 inches. You measure at the narrowest point of your torso, usually just above the belly button, while breathing out normally. This single number is a surprisingly strong predictor of cardiometabolic risk and works across different body types and ethnicities better than BMI alone.
Body Fat Percentage by Sex
Women naturally carry more essential body fat than men, which means the healthy ranges differ significantly between sexes. General body fat categories break down like this:
- Essential fat: 9–11% for women, 3–5% for men
- Athletic range: 12–19% for women, 6–13% for men
- Fitness range: 20–24% for women, 14–17% for men
- Average/acceptable: 25–29% for women, 18–24% for men
Most people who exercise a few times a week and eat reasonably well fall in the fitness or average range. You don’t need to be in the athletic range to be healthy. Dropping below the essential fat threshold is dangerous and disrupts hormone production, immune function, and organ protection. For women especially, very low body fat can cause menstrual cycles to stop and weaken bones over time.
Getting your body fat measured precisely requires tools like a DEXA scan or hydrostatic weighing. Bathroom scales that estimate body fat through electrical impedance give a rough idea but can swing several percentage points depending on your hydration level. If you want a reliable baseline, a DEXA scan at a clinic or university lab typically costs $40 to $100.
Why the “Right” Weight Shifts With Age
If you’re over 65, the standard BMI advice doesn’t fully apply. A large study published in the Journal of Epidemiology & Community Health found that the lowest mortality risk for older adults fell in the 25 to 29.9 BMI range, a category technically labeled “overweight.” Both men and women in that range outlived those in the so-called healthy BMI category. The likely explanation is that carrying a modest reserve of weight provides a buffer during illness, surgery, or periods of reduced appetite that become more common with age. Being underweight in your later years poses a greater risk than carrying a few extra pounds.
On the other end of the age spectrum, children and teens are evaluated differently. The CDC uses BMI-for-age percentiles rather than fixed cutoffs because kids’ bodies change so rapidly. A healthy weight for a child falls between the 5th and 85th percentile compared to other children of the same age and sex. Overweight is the 85th to 95th percentile. A pediatrician tracks these percentile trends over time rather than focusing on any single measurement.
When Muscle Makes the Scale Misleading
If you strength train regularly, your weight may push you into the “overweight” BMI category even though your health markers are excellent. Researchers use something called the fat-free mass index (FFMI) to account for this. It measures how much of your weight comes from bone, muscle, and organs rather than fat. For men with a normal BMI, typical FFMI values run 18.1 to 21.7. For women, 15.1 to 17.0. Values above those ranges suggest above-average muscle mass, meaning your BMI is elevated because of muscle, not excess fat.
You don’t need to calculate your FFMI to get the picture. If your waist-to-height ratio is healthy, your blood pressure is normal, and your blood sugar and cholesterol are in range, a BMI of 26 or 27 driven by muscle is not the same health concern as the same BMI driven by belly fat. Context matters far more than a single number.
Signs Your Weight Is in a Healthy Place
Rather than fixating on a specific number, it helps to look at the cluster of signals your body gives you. Metabolically healthy people, regardless of what the scale says, tend to share certain traits: fasting blood sugar under 100 mg/dL, blood pressure below 130/85, and triglycerides (a type of blood fat) below 150 mg/dL. When three or more of those markers go out of range along with a large waist, it’s called metabolic syndrome, and it dramatically increases the risk of heart disease and diabetes.
Practical signs of a healthy weight are less clinical but just as meaningful. You can walk up a flight of stairs without being winded. Your energy stays steady throughout the day. Your joints don’t ache from everyday movement. You sleep well. Your weight has been relatively stable for months rather than swinging in large cycles. These day-to-day signals often tell you more than any formula.
How to Find Your Personal Target
Start with the BMI range for your height. That gives you a window, not a verdict. A 5’4″ person has a healthy BMI range of roughly 108 to 145 pounds, which is a wide spread. Where you fall within that range depends on your frame, your muscle mass, and your age.
Next, measure your waist and compare it to half your height. If you’re comfortably below that line, your visceral fat is likely in a safe zone regardless of what the scale reads. If you’re above it, reducing waist circumference by even a couple of inches can meaningfully lower your risk profile.
If you have access to body composition testing, it fills in the gaps BMI can’t. Knowing your body fat percentage tells you whether excess weight is coming from fat or lean tissue, which changes the entire conversation. And if you’re over 65, don’t panic about a BMI in the mid-to-upper 20s. The data suggests that range is protective, not problematic, in later life.
The most honest answer to “what should my body weight be” is: whatever weight lets your blood markers stay healthy, your waist stay proportional, and your body move comfortably through daily life. That number is personal, and it’s almost always a range rather than a single digit on the scale.