Ideal Weight Calculator
Estimate an ideal body weight from height and sex with the Robinson formula, in kilograms and pounds, and see why it is only a rough reference.
Results
Ideal weight (Robinson)
- Approx lbs
- 134.0 lb
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Educational estimates · not financial advice · free, no signup
Formula / how it works
Robinson (1983): men 52 kg + 1.9 kg per inch over 5 feet; women 49 kg + 1.7 kg per inch over 5 feet. One inch = 2.54 cm; 1 kg = 2.2046 lb.
Read the guide: BMI: What the Number Means and What It Misses
Detailed guide
What it is, how to use it, how to read the numbers, common mistakes, a worked example, formulas, and FAQs.
What this calculator is
Ideal body weight formulas estimate a reference weight from height alone. The Robinson formula, published in 1983, starts at 52 kg for men and 49 kg for women at 5 feet, and adds a fixed amount for each inch above. It was designed for clinical uses such as drug dosing, not as a target for individuals. This calculator converts your height in centimetres to inches and applies the formula for the sex you choose, then displays the result in kilograms and pounds. Real healthy weights vary widely with frame, muscle, age and ethnicity, so treat it as one reference among many. Body composition and health markers say more than a number on a scale; talk to a clinician about personal goals.
When to use / who it helps
- You want a rough reference for a healthy weight.
- You are comparing several ideal weight formulas.
- You are reading a dosing or medical document that uses ideal body weight.
- You are curious how weight scales with height.
- You want the result in both kilograms and pounds.
How to use
Steps
- Enter your height in centimetres.
- Choose male or female.
- Read the estimated weight in kilograms.
- Read the pounds figure.
- Compare with BMI-based ranges if you want a range, not a point.
- Discuss personal goals with a healthcare professional.
How to interpret results
- The result is a single reference value, not a healthy range.
- Muscular people may weigh more than the formula without excess fat.
- The formula ignores age and frame size.
- Different formulas give different answers.
- It is less meaningful for very short or very tall people.
Common mistakes & gotchas
- Treating the result as a personal target.
- Entering height in inches in a centimetre field.
- Ignoring muscle mass and body composition.
- Using it for children or pregnant women.
- Comparing the result with a different formula without noting the method.
Worked example
Worked example — 170 cm
- 170 cm ÷ 2.54 = 66.93 inches, which is 6.93 inches over 5 feet.
- Female: 49 + 1.7 × 6.93 = 49 + 11.78 = 60.8 kg, which is about 134.0 lb.
- Male: 52 + 1.9 × 6.93 = 52 + 13.17 = 65.2 kg, which is about 143.7 lb.
- Check: 60.8 kg × 2.2046 ≈ 134.0 lb.
Result: At 170 cm, the Robinson ideal weight is 60.8 kg (134.0 lb) for a woman and 65.2 kg for a man.
To load the form's own demo values, tap Try example above the Calculate button.
How to calculate / formula
Robinson (1983): men 52 kg + 1.9 kg per inch over 5 feet; women 49 kg + 1.7 kg per inch over 5 feet. One inch = 2.54 cm; 1 kg = 2.2046 lb.
Frequently asked questions
What is the Robinson formula?
A 1983 formula estimating ideal body weight from height and sex.
Is ideal body weight the same as a healthy weight?
No. Healthy weights span a range and depend on many factors.
Why does the formula depend on sex?
The base value and the per-inch increment differ.
Does it account for muscle?
No.
Is it medical advice?
No. Discuss weight goals with a clinician.
Should I use BMI instead?
BMI is another simple screening tool with its own limits.
For education and personal goal-setting only — not medical advice, diagnosis, or treatment. Talk to a qualified clinician about your health. Full disclaimer