An ideal weight calculator can give you several numbers for the same height, which raises a fair question: if the results are different, which one should you aim for? The answer depends on what each number represents. Traditional ideal body weight formulas estimate a single reference weight, while a BMI-based calculation gives a broader range.
Use this ideal weight calculator to compare estimates from the Devine, Robinson, Miller, and Hamwi formulas, along with the healthy BMI range displayed for your height. Rather than treating the lowest or highest figure as your target, look at how the results compare and consider your current weight, body composition, activity level, and health goals.
Why Your Ideal Weight Results May Not Match
Suppose you enter a height of 5 feet 10 inches and the calculator returns three estimates close to 156–160 lb. You might wonder why it doesn’t provide one definitive answer. The difference comes from how each formula was developed and the values it uses to estimate body weight from height.
The Devine formula gives an estimate of about 160 lb for this example, while the Robinson and Miller formulas return approximately 158 lb and 156 lb, respectively. These are not three separate measurements of your body. They are mathematical estimates based on different equations.
The healthy BMI range answers a different question. For the same height, the calculator displays a range of approximately 133–179 lb. That wider interval is based on adult BMI values of 18.5 to 24.9, rather than on a formula that selects one ideal weight.
This distinction matters if you are using the result to decide whether you need to change your weight. Someone weighing 170 lb at this height should not automatically conclude that they need to lose 10–14 lb simply because the traditional equations return lower figures. Those estimates do not account for every detail of an individual’s body composition or health.
What Each Ideal Body Weight Formula Tells You
The calculator compares several established equations. They share the same broad purpose—estimating a reference weight from height—but they do not use identical calculations.
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Devine formula: Estimates ideal body weight using a baseline value and an additional amount for each inch above 5 feet. It was originally developed in a clinical context and remains widely referenced.
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Robinson formula: Uses different baseline values and height adjustments, so it can return a slightly different estimate for the same person.
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Miller formula: Uses another set of constants, producing its own estimate rather than simply repeating the Devine result.
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Hamwi formula: Uses a separate height-based calculation to estimate reference weight.
The formulas have a history in clinical practice, including medication-dosing calculations. They should not be mistaken for equations that can identify the exact weight at which every person will be healthiest. Research comparing ideal body weight equations has found meaningful differences between their estimates, and a single formula-derived number does not represent a universal target for every adult.
For that reason, the useful part of comparing these formulas is understanding the range of estimates—not trying to identify one equation as the perfect answer for your body.
Worked Example: Understanding the Numbers for Someone 5 ft 10 in Tall
Consider an adult man who enters a height of 5 feet 10 inches. The calculator’s example results are approximately:
| Result |
Estimated weight |
| Devine formula |
160 lb (72.6 kg) |
| Robinson formula |
158 lb |
| Miller formula |
156 lb |
| Healthy BMI range |
133–179 lb |
The three formula-based estimates cluster around the upper 150s to 160 lb. The BMI-based range covers a much wider span. Neither result tells you, by itself, how much muscle you carry, where you store body fat, how physically active you are, or whether a particular weight is appropriate given your medical history.
Now imagine you weigh 170 lb. That puts you above the three single-number estimates in this example, but still inside the calculator’s displayed BMI-based range. It would be misleading to treat the difference between 170 lb and 160 lb as an automatic instruction to lose 10 lb.
A better next step is to consider why you are checking your weight. Are you trying to understand a recent change, establish a goal with a healthcare professional, or assess your current weight in relation to your height? The answer affects how useful the result will be.
How Height, Sex, and Body Frame Affect the Estimate
A small input error can make a result less useful, and the calculator’s assumptions are worth understanding before you compare the figures.
Check your height carefully. If you are 5 feet 10 inches tall, enter 5 in the feet field and 10 in the inches field. Do not enter 5.10 as a decimal height. Feet and inches are separate units, and ten inches is not the same as 0.10 feet.
Choose the appropriate sex-based equation. The traditional formulas use different baseline values for men and women. This is part of the equations’ design; it does not mean that sex and height alone fully determine a healthy body weight.
Understand what body frame size can and cannot tell you. A frame-size adjustment is intended to account for differences in skeletal build. It does not directly measure body fat, muscle mass, fitness, or health. If the calculator’s frame selector changes an estimate, interpret that adjustment as an additional assumption rather than a precise measurement of your ideal weight.
If your result seems surprisingly high or low, check your height entries and frame selection first. Then compare the different formula results instead of assuming the calculator is incorrect because the numbers do not agree.
When the Calculated Weight Doesn’t Seem Right
An estimate can be mathematically correct and still be a poor description of an individual’s situation. Here are a few common reasons the number may not match what you expected.
You have a muscular build
A person who strength-trains regularly may weigh more than a height-based ideal weight estimate because these equations do not distinguish muscle from body fat. The formula cannot tell whether additional weight comes from muscle, fat, bone, or other body tissues.
What to do: Don’t use the ideal weight figure alone to decide that you need to lose weight. Consider your training goals, body composition where appropriate, and broader health indicators.
You are much shorter or taller than average
Traditional ideal body weight formulas use linear relationships between height and weight. Research has highlighted limitations in how some of these equations correspond with BMI at the shorter and taller ends of the height range.
What to do: Treat the result cautiously if your height is outside the range for which a formula is commonly used. Compare it with the BMI-based range and seek individual guidance if the number will influence an important health decision.
Your weight is within the range, but you still have concerns
Falling within a BMI-based range does not establish that every aspect of your health is good. Likewise, being outside it does not explain the cause of your weight or diagnose a health condition.
What to do: Consider the result alongside your health history, weight changes over time, activity, and any concerns you have about nutrition or physical wellbeing. A healthcare professional can help interpret these factors together.
The number is lower than your current weight, so you assume weight loss is necessary
This is one of the easiest mistakes to make with an ideal weight calculator. A formula produces a reference figure, not an individual assessment of whether weight loss is beneficial or necessary.
What to do: Start with the reason you used the calculator. If you are simply curious, the comparison may be enough. If you are planning a weight change, choose a realistic goal based on your circumstances rather than treating the lowest displayed number as the finish line.
What Should You Do With Your Ideal Weight Result?
The result is most useful when it helps answer a specific question, rather than creating a new target without context.
If you want to understand how your current weight relates to your height, use the BMI Calculator as a complementary check. BMI is a screening measure, not a diagnosis, and it does not distinguish fat from muscle. Its value is in providing another reference point—not in replacing a broader assessment.
If you are already within the displayed BMI range and have no particular health concern, you may not need to change your weight just to match one of the traditional formula estimates. A calculated ideal weight is not a requirement that everyone must reach.
If you are considering losing or gaining weight, first identify what you want to achieve. Your goal may relate to fitness, strength, a change in health, or advice from a clinician. Those situations call for different decisions, and the ideal weight calculator cannot determine which one applies to you.
For people who are planning a change in weight, daily energy needs are a separate consideration from ideal body weight. The Calorie Calculator can help estimate daily calorie needs using age, body size, and activity level. It does not determine whether you should lose weight or prescribe a target based on the ideal weight results.
The key is to use each calculation for the question it can reasonably answer. A height-based formula estimates a reference weight; a BMI calculation relates weight to height; neither tells the whole story about an individual.
How the Devine Ideal Weight Formula Works
The Devine formula uses a baseline weight for a height of 5 feet and adds a fixed amount for each additional inch. In its commonly cited form:
For a 5 ft 10 in man, the height is 10 inches above the 5-foot reference point. The calculation is therefore 50 kg + (10 × 2.3 kg), giving an estimated ideal body weight of 73 kg, or about 161 lb before rounding.
This calculation illustrates why the height fields matter: the equation counts inches above 60 inches, not decimal portions of a foot. Robinson and Miller use different constants, which is why their results are not identical to the Devine estimate.
These equations are historical reference methods rather than comprehensive models of health. They do not incorporate every factor that can affect an individual’s appropriate weight, including body composition, age-related changes, medical conditions, or personal circumstances.
A final point: Your calculated ideal weight is best treated as one piece of information, not a verdict on your body. Compare the results, understand their limitations, and make any decisions about weight in the context of your actual needs.
