BMI Calculator for Women and Men (New Zealand)
✅ WHO BMI Categories | ✅ Imperial & Metric | ✅ Dietitian-Reviewed 2026
Our free BMI calculator for women and men gives you your Body Mass Index, WHO health category, and healthy weight range in seconds. Enter your height and weight below.
BMI Categories — What Your Result Means
| BMI Range | Category (WHO) | Health Risk |
|---|---|---|
| Below 18.5 | Underweight | Nutritional deficiency risk |
| 18.5 – 24.9 | Normal / Healthy | Lowest risk |
| 25.0 – 29.9 | Overweight | Increased risk |
| 30.0 – 34.9 | Obese Class I | High risk |
| 35.0 – 39.9 | Obese Class II | Very high risk |
| 40.0+ | Obese Class III | Extremely high risk |
BMI Calculator for Women
Women naturally carry more essential body fat than men due to reproductive biology. The standard WHO BMI categories apply to both sexes, but a BMI of 21–23 is often considered optimal for women in terms of long-term health outcomes.
Healthy BMI Weight Ranges for Women (5'4" / 163 cm example)
| BMI | Weight (lbs) | Weight (kg) | Category |
|---|---|---|---|
| 18.5 | 108 lbs | 49 kg | Underweight threshold |
| 21.5 | 125 lbs | 57 kg | Optimal for women |
| 24.9 | 145 lbs | 66 kg | Healthy upper limit |
BMI Calculator for Men
Men have higher muscle mass and lower essential body fat than women. A BMI of 22–24 is often cited as the optimal range for men. Importantly, muscular men (particularly athletes) may fall into the "overweight" BMI category despite very low body fat. In these cases, body fat percentage is a more accurate health indicator.
Healthy BMI Weight Ranges for Men (5'10" / 178 cm example)
| BMI | Weight (lbs) | Weight (kg) | Category |
|---|---|---|---|
| 18.5 | 129 lbs | 58 kg | Underweight threshold |
| 22.5 | 157 lbs | 71 kg | Optimal for men |
| 24.9 | 174 lbs | 79 kg | Healthy upper limit |
How to Calculate BMI — The Formula
BMI is calculated by dividing your weight by your height squared:
Metric Formula
Example: A person weighing 70 kg and 1.75 m tall: BMI = 70 ÷ (1.75²) = 70 ÷ 3.0625 = 22.9 (Healthy)
Imperial Formula
Example: A person weighing 154 lbs and 68 inches (5'8") tall: BMI = (154 ÷ 4624) × 703 = 23.4 (Healthy)
Limitations of BMI
BMI is a useful population-level screening tool, but it has known limitations:
- Doesn't distinguish muscle from fat — Athletes with high muscle mass are often incorrectly classified as overweight
- Age bias — Older adults naturally lose muscle and gain fat, which BMI doesn't capture
- Ethnic variation — Some Asian populations face metabolic risks at lower BMI thresholds (23+)
- Doesn't show fat distribution — Abdominal fat carries higher risk than hip/thigh fat at the same BMI
For a more complete health picture, use BMI alongside our Body Fat Percentage Calculator.
Related Calculators
- Body Fat Percentage Calculator — More accurate than BMI for body composition
- Weight Loss Calculator — Calorie target and timeline to your goal weight
- TDEE Calculator — Total Daily Energy Expenditure
- BMR Calculator — Basal Metabolic Rate
- Calorie Calculator — Daily calorie needs
Frequently Asked Questions
How do I calculate my BMI?
Use the calculator above, or manually: BMI = weight (kg) ÷ height² (m²). In imperial: BMI = (weight lbs ÷ height inches²) × 703. Enter your stats in the calculator above for an instant result.
What is a healthy BMI for women?
The healthy BMI range for women is 18.5 to 24.9 (WHO classification). Research suggests a BMI of 21–23 is optimal for long-term health in women. Women naturally carry more essential body fat (10–13%) than men (2–5%).
What is a healthy BMI for men?
The healthy BMI range for men is 18.5 to 24.9. A BMI of 22–24 is considered optimal for most men. Muscular men may have a BMI of 25–27 while having low body fat — in these cases, also check body fat percentage.
What BMI is considered obese?
A BMI of 30 or above is classified as obese (Class I: 30–34.9, Class II: 35–39.9, Class III: 40+). A BMI of 25–29.9 is classified as overweight. The CDC recommends consulting a healthcare provider for personalized guidance.
Is BMI accurate for athletes and muscular people?
No — BMI cannot distinguish fat from muscle. A muscular bodybuilder may have a BMI of 28 ("overweight") despite only 8% body fat. For athletes, body fat percentage is a far more accurate health indicator.
Medically Reviewed By
Dr. Sarah Jenkins, RD — Clinical Dietitian & Weight Management Specialist
Dr. Jenkins has over 15 years of experience in clinical nutrition and metabolic health.
Last reviewed: July 2026 | Sources: WHO Obesity Fact Sheet · CDC BMI Information