Skip to main content
Ideal body weight (IBW), what it means and how it is estimated

Health

Ideal weight by height and how to estimate the reference

What ideal body weight (IBW) means, how the Devine formula estimates a reference from height, and why it is not a mandatory target.

8 min read

"What should I weigh?" often asks for one magic number. Ideal weight (IBW) answers with something else. It is a height-based reference, usually from the Devine formula, useful for a quick sense of scale.

That number helps you orient. It is not a mandatory target and it does not replace BMI risk reading or body composition.

To see the reference now, use the ideal weight calculator. Below you will find where the idea came from, how to estimate yours, and what to do if you are far from that point.

Looking for a calculator right now?

Ideal weight calculator

What ideal weight is (and what it is not)

Ideal weight is a reference weight for your height, better suited to your build and, in general, within a range considered healthy.

In adults, one of the most common ways to get that sense is BMI (body mass index), which crosses height and weight. In children and teens the calculation changes with age and sex, so the reference for boys and girls is not the same. In those cases, a paediatrician or dietitian usually guides you better.

BMI and ideal weight formulas do not separate fat, muscle, and fluid retention. They work as a starting point, not as absolute truth about your body.

Someone with a lot of muscle mass can look "above ideal" without excess fat. The same goes for fluid retention or swelling. In those cases, an assessment with a dietitian often helps more than looking at the number alone.

Formulas such as Devine (1974), Robinson, Miller, and Hamwi were created for clinical and actuarial uses, such as drug dosing and quick reference. Each can give a slightly different number for the same person, and all of them use only height and gender. That is why they ignore:

  • Muscle mass: someone who trains hard can weigh more and be well.
  • Bone structure: heavier bones push the scale up.
  • Age and ethnicity: composition and ranges can vary.
  • Goals: athlete, recovery from illness, or focus on composition change what makes sense to aim for.

Timeline of the ideal weight concept, from actuarial and clinical use to a modern medical reference.

Ideal weight or healthy range, what to aim for

  • Ideal weight (e.g. Devine) = one number for your height and gender. Good for quick reference and clinical context.
  • Healthy weight range (e.g. BMI from 18.5 to 24.9) = a band linked to lower health risk. It fits different builds. Two people of the same height can both be fine at different weights.

For personal goals in daily life, the BMI range (see the BMI guide) is often more useful than a single "ideal". You can use ideal weight as a reference or midpoint and aim to sit in the healthy range, also looking at how you feel, how you perform, and (if you have it) body fat percentage.

In practice, the best weight is one you can sustain with balanced food, movement, and sleep, not just what the formula returns.

Visual comparison of a single ideal body weight (IBW) point within a wider healthy BMI range (18.5–24.9).

How to estimate your reference weight

The simplest way is the ideal weight calculator. It applies the Devine formula with your height in cm and shows the result right away.

If you want a sense of what comes out before using the calculator, Devine crosses height and gender and returns a weight in kg. Quick example: a woman at 1.70 m is around 61 kg, a man the same height around 66 kg. These are ballpark figures, not rigid targets.

Other formulas (Robinson, Miller, Hamwi) exist and can vary by a few kg. For daily life, what matters is knowing if you are near, above, or below that reference, not hitting the exact gram.

Devine formula flow, with height and gender producing ideal body weight (IBW) in kilograms.

How to get there healthily

When your weight is far from the reference, the best path is to seek professional guidance. A dietitian plans food for losing or gaining weight, depending on your case. A fitness professional helps with exercises suited and safe for your body. A doctor steps in when there is illness, severe obesity, or unexplained weight loss.

If you are above the reference weight

The focus is usually more balanced eating and more movement, with gradual changes you can keep in daily life. Foods rich in fibre, quality protein, and fewer ultra-processed products help with fullness and routine, without needing an extreme diet.

Beyond food, exercise makes a difference. It raises energy use and improves fitness. To understand calories and deficit more calmly, see our calories and TDEE guide.

In more severe obesity, or when diet and activity were already tried with support and the result is still insufficient, a doctor may assess medication or, in specific cases, bariatric surgery. Always with follow-up, never as a shortcut on its own.

Beyond weight, it also helps to look at BMI and, if it makes sense in your case, measures such as waist circumference. Our BMI guide explains how that helps you understand cardiovascular risk.

If you are below the reference weight

Weight gain needs to be healthy. The goal is to gain mass and nutrients, preferably lean mass rather than fat alone.

That is why fast food, fried food, and sweets in excess are not a good choice for gaining weight healthily. They push calories but deliver little quality nutrition.

In practice, a dietitian often works on regular meals, protein at each meal (eggs, dairy, chicken, fish, legumes), and gradual calorie adjustment. For daily protein amounts, our protein guide complements.

When appetite disappears, weight drops for no clear reason, or tiredness does not pass, a medical check is worth it. There may be a physical or emotional cause behind it, and tests help investigate.

For height-and-weight risk banding, the BMI guide and the BMI calculator complete the reading without turning into another isolated number on the scale.

When ideal weight is used

  • Clinical settings: dosing of some medicines, fluid calculations, and nutrition support sometimes use IBW.
  • Dietetics: some professionals use it as a starting point for weight goals.
  • Personal reference: compare your current weight to your "ideal" to see if you are in the same ballpark. Do not treat it as a rigid target.

In daily life, treat those uses as context. For personal goals, a BMI range and how you feel usually guide you better than a single number.

FAQ

Should I aim exactly for my ideal weight?

No. It is a reference, not an obligation. For personal goals, a healthy BMI range (from 18.5 to 24.9) and a body fat % that makes sense usually matter more than one number. Ideal weight can fall inside that range.

I am above or below my ideal weight. What should I do?

It depends on your context. If BMI is also outside the range, waist size worries you, or you do not feel well, talk to a dietitian and doctor before deciding to lose or gain weight. Above ideal, the path usually involves balanced eating and more movement. Below, the focus is gaining mass and nutrients with support, not empty calories alone. See How to get there healthily above.

I am muscular and weigh more than my "ideal." Is that bad?

Not necessarily. Ideal weight does not account for muscle or fluid retention. If BMI is healthy and body fat % is reasonable, being above "ideal" can be normal. Focus on health and composition, not one formula alone.

Which formula does the calculator use?

The ideal weight calculator here uses Devine, with height in cm. Other formulas (Robinson, Miller, Hamwi) exist and can give close but not identical results.

Why do different formulas give different numbers?

Each came from different populations and purposes. Devine is widely used. Robinson, Miller, and Hamwi can give slightly higher or lower values. In general the difference is a few kg.

Does it work for very short or very tall people?

Devine was designed for adults in typical height ranges. Outside that band, the number is less useful. Prefer BMI range, body fat %, and professional assessment.

Can I use ideal weight during pregnancy?

Not as the main reference. Weight changes because of the baby, placenta, and amniotic fluid. Prenatal care uses specific curves. A doctor or obstetrician interprets pregnancy weight.

Bottom Line

Ideal weight is a reference number for your height (usually via Devine), useful for a quick idea. For height-and-weight risk banding, the natural next step is the BMI guide.

Use the ideal weight calculator to estimate yours. If you are far from the reference, seek a gradual plan with a dietitian and fitness professional. Your best weight is the one that sustains health, energy, and goals over the long term.

This article is for general education only. It is not medical advice, a diagnosis, or a personal meal or exercise plan. Weight and body image can be sensitive topics, and a doctor or registered dietitian can help interpret ideal weight, BMI, and related measures for your situation.

References

Enjoyed this guide?

Try a related calculator or explore more reads on the same topic.

Open BMI Calculator (Category & Healthy Range)See related articles

← All articles