Ideal Weight

Devine formula healthy target weight — height in any unit.

Ideal weight
314 kg
314
In kg
693
In lb

How to Calculate Your Ideal Weight

  1. **Enter your height** – Input your height in feet and inches (or centimetres; the calculator converts automatically).
  2. **Select your biological sex** – Choose Male or Female, as the Devine formula uses different baseline values for each.
  3. **Click Calculate** – The calculator instantly applies the Devine formula and displays your Ideal Body Weight in kilograms and pounds.
  4. **Review your result** – Your IBW is shown alongside a brief interpretation. Remember this is a statistical estimate, not a personalised medical target.
  5. **Explore related tools** – Use the BMI or Body Fat calculators linked below for a more complete picture of your body composition.

The Devine Formula for Ideal Body Weight

**Male:** IBW (kg) = 50 + 2.3 × (H_in − 60)

**Female:** IBW (kg) = 45.5 + 2.3 × (H_in − 60)

Where H_in is height in **inches**.

The Devine formula, published by Dr. B.J. Devine in 1974, calculates Ideal Body Weight (IBW) in kilograms from height in centimetres. It was originally created to standardise drug dosing in clinical settings and remains the most commonly cited IBW equation today.

There are separate equations for males and females because body composition differs by biological sex. The baseline weight (50 kg for males, 45.5 kg for females) represents the estimated ideal weight at exactly 5 feet (152.4 cm), and an additional 2.3 kg is added per inch above that baseline height.

  • IBW — Ideal Body Weight in kilograms — the estimated target weight output.
  • 50 (male) / 45.5 (female) — The baseline IBW in kg at exactly 5 feet (60 inches / 152.4 cm) for males and females respectively.
  • 2.3 — The weight increment in kilograms added for each inch of height above 5 feet (60 inches).
  • H_in — The person's height converted to inches (1 inch = 2.54 cm). The formula is only valid for heights at or above 5 feet (60 inches).

Worked Example – Ideal Weight for a 5 ft 9 in Female

Sex: Female | Height: 5 ft 9 in (69 inches)
IBW = 45.5 + 2.3 × (69 − 60)
IBW = 45.5 + 2.3 × 9
IBW = 45.5 + 20.7
IBW = 66.2 kg

Result: Ideal Body Weight ≈ **66.2 kg (approximately 146 lb)**

What Your Result Means

For a female standing 5 feet 9 inches tall, the Devine formula gives an Ideal Body Weight of 66.2 kg (≈ 146 lb). This means that, according to the Devine model, a body weight in the vicinity of 66 kg is the clinical reference point used for that combination of height and sex. Your actual healthy weight range may span several kilograms above and below this figure depending on your muscle mass, bone density, age, and individual physiology. Always discuss weight goals with a qualified healthcare professional.

Understanding Ideal Weight

What Is Ideal Body Weight?

Ideal Body Weight (IBW) is a statistical estimate of the weight at which a person of a given height and sex is considered to be at a healthy baseline. It is widely used in clinical medicine — particularly for calculating medication doses, ventilator settings, and nutritional needs — rather than as a strict aesthetic or personal fitness target.

History of the Devine Formula

The Devine formula was introduced by B.J. Devine in a 1974 paper on drug dosing. Interestingly, Devine never intended it as a definitive health standard; it was a convenient approximation. Despite this, it became the default IBW reference in clinical practice and pharmacology for decades.

Other Common IBW Methods

| Formula | Male Baseline | Female Baseline | Increment per inch | |---|---|---|---| | Devine (1974) | 50 kg | 45.5 kg | 2.3 kg | | Robinson (1983) | 52 kg | 49 kg | 1.9 kg (M) / 1.7 kg (F) | | Miller (1983) | 56.2 kg | 53.1 kg | 1.41 kg (M) / 1.36 kg (F) | | Hamwi (1964) | 48 kg | 45.4 kg | 2.7 kg (M) / 2.3 kg (F) |

The Devine formula is used in this calculator because it is the most clinically referenced standard.

Limitations to Keep in Mind

  • Not suitable for children or teens – Separate paediatric growth standards apply.
  • Does not account for muscle mass – Athletes and muscular individuals will often exceed their IBW while remaining very healthy.
  • Not valid below 5 feet (152.4 cm) – The formula can produce unrealistic values for shorter individuals.
  • Race and ethnicity – Body composition norms vary across populations; a single formula cannot capture this diversity.

⚠️ Disclaimer: This calculator is for educational purposes only and does not constitute medical advice. IBW is a clinical reference tool, not a personal health prescription. Consult a licensed healthcare provider before making any changes to your diet, exercise routine, or health plan.

Common Mistakes

  • **Using height in centimetres directly** – The Devine formula requires height in inches. Always convert: divide cm by 2.54 to get inches.
  • **Applying the formula to heights below 5 feet** – The formula is not validated for heights under 60 inches and can give misleadingly low results.
  • **Treating IBW as a strict goal weight** – IBW is a statistical baseline, not a personalised target. Healthy weight ranges span roughly ±10% around the IBW figure.
  • **Confusing IBW with BMI** – These are different tools. BMI is a ratio of weight to height squared; IBW is a single estimated weight value derived from height alone.
  • **Ignoring sex selection** – Using the wrong sex baseline (50 vs. 45.5 kg) will shift the result by 4.5 kg, making accuracy impossible.

Common Questions About Ideal Weight

What is a good weight for a 5'10" male?

Using the Devine formula: IBW = 50 + 2.3 × (70 − 60) = 50 + 23 = **73 kg (approximately 161 lb)**. This is the clinical reference point; individual healthy ranges may vary by ±5–10%.

How accurate is the Devine formula compared to other IBW methods?

All IBW formulas, including Devine, Robinson, Miller, and Hamwi, are population-level statistical estimates with inherent error margins. Studies show differences of up to 10–15% between methods for the same individual. No single formula perfectly predicts every person's optimal weight. Devine is most cited in clinical pharmacology contexts.

Does ideal body weight change with age?

The original Devine formula does not adjust for age. However, research suggests that slightly higher body weights may be associated with better health outcomes in older adults (a phenomenon sometimes called the 'obesity paradox'). For age-adjusted weight guidance, consult a healthcare provider.

What is the difference between ideal body weight and adjusted body weight?

Adjusted Body Weight (AdjBW) is used in clinical settings when a patient's actual weight is significantly above their IBW (typically more than 30% over). The formula is: AdjBW = IBW + 0.4 × (Actual Weight − IBW). This is commonly used for drug dosing in obese patients.

How do I convert my ideal weight from kg to pounds?

Multiply kilograms by 2.2046. For example, 66.2 kg × 2.2046 ≈ **146 lb**. Our calculator displays both units automatically.

Frequently Asked Questions

What formula does this Ideal Weight Calculator use?

It uses the **Devine formula (1974)**: IBW = 50 + 2.3 × (height in inches − 60) for males, and IBW = 45.5 + 2.3 × (height in inches − 60) for females. This is the most widely used clinical IBW reference equation.

Is the ideal weight the same as a healthy weight?

Not exactly. Ideal Body Weight from the Devine formula is a clinical reference point — it tells you one estimate of a target weight. A healthy weight range is broader and considers factors like body composition, age, fitness level, and health markers. The IBW is best used as a rough guideline, not an absolute goal.

Can I use this calculator if I'm under 5 feet tall?

The Devine formula is technically only validated for heights at or above 5 feet (152.4 cm / 60 inches). For shorter individuals, the formula can produce values that are too low to be physiologically meaningful. Speak with a healthcare provider for a more appropriate assessment.

Should I include my shoes when measuring height?

No — always use your barefoot height for accurate results. Even thin shoes add 1–2 cm, which translates into a 0.9–1.8 kg difference in your calculated IBW.

How does the Devine formula differ for males and females?

Males use a baseline of 50 kg at 5 feet, while females use 45.5 kg. Both add 2.3 kg per inch above 5 feet. The 4.5 kg difference reflects average differences in bone density and lean mass between sexes at the same height.

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