If you are comparing ideal weight formulas, the Devine formula and BMI are usually the two simplest places to start. The Devine formula gives one target weight from height and sex, while BMI gives a range of weights that fall within a standard BMI band.
They can point you in a useful direction, but they are not the same thing. One gives a single number, the other gives a range, and both leave out body composition, muscle mass, age, and other factors. For a quick background on the concept of body weight itself, see the Human body weight overview.
What the Devine formula says
The Devine formula is a classic ideal-weight rule of thumb. It uses height and sex to estimate a target body weight.
The formula
- Men: 50 kg + 2.3 kg for each inch over 5 feet
- Women: 45.5 kg + 2.3 kg for each inch over 5 feet
That means the formula starts from a base weight at 5 feet, then adds the same amount for each extra inch.
What it assumes
The Devine formula was created as a simple estimate, not as a medical diagnosis. It treats height as the main driver and assumes the same step-up per inch for everyone above 5 feet. That makes it easy to use, but also easy to oversimplify.
How BMI gives a weight range
BMI, or body mass index, turns height and weight into a single number. For “healthy” BMI, the usual reference band is 18.5 to 24.9. If you already know your height, you can reverse that formula and get a weight range rather than a single target. You can also compare your result with a dedicated BMI calculator if you want the arithmetic done for you.
Why the result is a range
BMI does not say that one exact weight is best. Instead, it says that for a given height, any weight that produces a BMI between 18.5 and 24.9 is within the reference band. That makes BMI broader than Devine and often more realistic as a screening tool.
Side-by-side example at a given height
Here is how the two methods can differ for the same height. The example below uses a hypothetical height of 5 feet 8 inches.
Devine formula example
For a man at 5 feet 8 inches, the formula is:
- 50 kg + 18.4 kg
So the Devine estimate is 68.4 kg.
For a woman at 5 feet 8 inches, the formula is:
- 45.5 kg + 18.4 kg
So the Devine estimate is 63.9 kg.
BMI healthy-range example
For BMI, you first convert height to meters, then apply the BMI band of 18.5 to 24.9.
At 5 feet 8 inches, the lower end of the BMI range is:
- 55.19 kg
The upper end is:
- 74.28 kg
So the BMI-based healthy range for this height is 55.19 kg to 74.28 kg.
What this comparison shows
The Devine formula gives one point estimate for the same height, while BMI gives a band. That difference matters because a single “ideal” number can look more precise than it really is.
Where the Devine formula falls short
The Devine formula is easy to calculate, but it has clear limits.
Main weaknesses
- It uses sex as a binary input, which may not fit everyone neatly.
- It assumes height alone can define an ideal weight.
- It does not adjust for muscle, fat distribution, or frame size.
- It gives one target, even though many healthy weights can exist for the same height.
Practical issue
If you are muscular, the formula may label a healthy weight as too high. If you have low muscle mass, it may still give a number that does not reflect your overall health. That is why it works better as a rough estimate than as a final answer.
Where BMI falls short
BMI is widely used because it is simple and consistent, but it also has blind spots.
Main weaknesses
- It does not separate muscle from body fat.
- It does not show where fat is carried on the body.
- It does not account for bone structure or age.
- It gives a screening band, not a diagnosis.
Why that matters
Two people with the same BMI can look and feel very different. One may have more muscle, another more body fat. The number alone does not tell you which is which, so BMI should be treated as one clue rather than the whole picture. If you want to understand how BMI bands are usually read, this BMI categories guide is a useful companion.
Which formula is more useful?
That depends on what you want the number for.
Use Devine when you want
- a quick estimate of a target weight from height
- a simple rule of thumb
- a starting point for comparison
Use BMI when you want
- a weight range for a given height
- a standard screening measure
- a way to compare many people using the same method
Best way to think about them
Devine is narrower. BMI is broader. Devine says, “Here is one estimated target.” BMI says, “Here is the range where your weight may fall for this height.” If you are tracking change over time, a weight loss calculator can help you model the size of the change itself, even though it does not replace a health assessment.
A better way to use both numbers
You do not have to choose one formula and ignore the other. Used together, they can give a more balanced view.
A practical approach
- Calculate the Devine estimate for a quick reference point.
- Calculate the BMI-based healthy range for the same height.
- See whether the Devine number lands inside that BMI band.
- Compare the result with how you actually feel and function.
- Treat large mismatches as a signal to look deeper, not as a problem by themselves.
What to watch for
If the two methods disagree a little, that is normal. If they disagree a lot, the issue may be that one method is too simple for your body type or situation. A weight converter can also help if you are moving between kilograms and pounds while checking results from different sources.
When to look beyond formulas
Ideal-weight formulas are most useful as screening tools. They are not designed to answer every question about health.
Look beyond them if you
- are an athlete or very muscular
- have recently lost or gained weight quickly
- are pregnant
- are a child or teen
- have a medical condition that affects weight or fluid balance
What to do instead
If the number matters for health, use it as a starting point and then check it against other signs: waist size, energy level, strength, eating pattern, and medical guidance when needed. If you are trying to change your weight intentionally, pairing these formulas with a weight gain calculator or weight-loss planning tool can make the goal more concrete without pretending the formula is definitive.
Frequently asked questions
- Is the Devine formula still used today?
- Yes, it is still used as a quick reference in some settings. It is not a final measure of health, though, because it ignores body composition and other factors.
- Why does BMI give a range instead of one ideal weight?
- BMI is built as a band of healthy values, not a single target. For a given height, several weights can fit inside that band.
- Can the Devine formula and BMI give very different results?
- Yes. The Devine formula gives one point estimate, while BMI gives a range, so the results can differ even for the same height. That does not automatically mean one is wrong.
- Which is better for athletes?
- Neither is perfect for athletes, because both can miss the effect of high muscle mass. A fit athlete may look “overweight” by BMI and still be healthy.
- Does a healthy BMI guarantee good health?
- No. BMI is only a screening tool. It does not show blood pressure, fitness, diet quality, or where body fat is stored.
- Can I use these formulas to set a weight goal?
- Yes, but only as a rough starting point. A better goal is usually one that also fits your energy, strength, and long-term routine.
- Should I rely on one formula alone?
- No. If you want a practical estimate, compare the Devine formula with the BMI range and then check whether the result makes sense for your body and situation. If you need a number for planning, use a calculator, then verify it with a health professional if the result affects your decisions.
About this article
Written by Yahav Atia, WSO – the digital agency (wso.co.il) that owns and founded this site, with the help of AI, and passed automated quality checks before publication. Numbers in the worked examples were computed in code, not estimated. This is general information, not medical or nutritional advice; for personal questions talk to a qualified clinician.