BMI Calculator
🇳🇿 New Zealand version
New Zealand guidance reads adult BMI in four bands, from Underweight to Obesity at 30 and above, and this page works in centimetres and kilograms. It shows your band, the weight range that sits in the healthy band for your height, and the Ministry of Health and Health NZ notes on lower thresholds for people of Asian descent. Take the number to your GP to put it in context.
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Categories: Ministry of Health adult categories (WHO cut-offs), Ministry of Health: Weight management in adults (2017).
The Ministry guideline advises considering lower waist thresholds for people of Asian ethnicities. Health NZ says people of Asian descent can have a lower healthy BMI. No numbers are given.
Adult bands do not apply to children and young people; New Zealand has separate clinical guidelines for them.
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New Zealand rules and figures
- The Ministry of Health guideline for adults sorts BMI into four groups, starting at Underweight under 18.5 and ending at Obesity for any figure of 30 or more, with Healthy weight and Overweight between.
- The Ministry guideline advises considering lower waist thresholds for people of Asian ethnicities, and Health NZ says people of Asian descent can have a lower healthy BMI. Neither source gives numbers.
- Adult bands do not apply to children and young people. New Zealand has separate clinical guidelines for them, published by the Ministry of Health.
- Kilograms and centimetres are the defaults on the New Zealand page, with 170 cm and 70 kg filled in when it opens.
Sources: Ministry of Health: Weight management in adults (2017) (checked 2026-11-08); Health NZ: Healthy weight BMI calculator (checked 2026-11-08); Ministry of Health: Weight management in children and young people (checked 2026-11-08)
How the BMI calculator works
Weight in kilograms is divided by height in metres squared, and the result is placed in one of the Ministry of Health's four adult bands.
BMI = kg ÷ m². Ministry of Health bands: Obesity from 30, Overweight from 25, Healthy weight from 18.5, Underweight under 18.5
- The page opens in metric with 170 cm and 70 kg entered. A unit you pick yourself, such as lb or stones, stays selected as you type.
- Obesity is one band on the New Zealand page, from 30 upward, so the classes shown on the UK and Australian pages do not appear here.
- The Ministry guideline advises considering lower waist thresholds for people of Asian ethnicities, and Health NZ says people of Asian descent can have a lower healthy BMI. Neither gives numbers, so the page shows the notes without changing any cut-off.
- Children and young people have their own clinical guidelines, and the adult bands here are not meant for them.
How to use the BMI calculator
- Enter height in centimetres. Type your height in the first box, or switch the unit to feet and inches if that is how you know it.
- Enter weight in kilograms. Type your weight from the scales. Choose lb or st first if you weigh yourself in those units.
- Look at your band and range. Your BMI appears with its band name, then the kilogram limits of the healthy band for someone of your height.
- Try the other BMI methods. The method list switches between the standard figure, an age-adjusted one and BMI Prime.
- Add measurements and keep a record. Waist size on the Body Composition tab gives a waist-to-height ratio. Save Entry stores the reading in this browser.
Example: 175 cm and 88 kg, then 165 cm and 82 kg
Take someone 175 cm tall weighing 88 kg: BMI 28.7, Overweight, with 56.7 to 76.3 kg as the healthy range. Now 165 cm and 82 kg: BMI 30.1 lands in Obesity, and the healthy range for that height is 50.4 to 67.8 kg.
When to use the BMI calculator
- Checking where you sit in the bands. Enter height and weight to see whether the result is Healthy weight, Overweight or Obesity on the Ministry bands.
- Setting a weight range to ask about. Use the Healthy Weight Range for your height as a starting point for a conversation with your GP.
- Following a trend. Save a dated entry after each weigh-in and watch the BMI move over weeks.
What the BMI calculator does not do
- BMI uses height and weight only, so it cannot show muscle, bone or where fat is carried.
- The Ministry and Health NZ mention lower thresholds for people of Asian descent without numbers, so the page applies one set of bands to everyone.
- The page does not split Obesity into classes, because the Ministry bands used here have a single Obesity band.
- It is a screening figure. A GP can interpret it with waist size, blood tests and your history.
When something else is a better fit
- When you want a body fat estimate from a tape measure, use the Body Fat Calculator.
- When you want target weights worked out from height-based formulas, use the Ideal Weight Calculator.
- When you want to talk through weight management, use your GP or a dietitian, who can look at waist size and health history.
Questions about the BMI calculator
What does Obesity mean on this page?
It means a BMI of 30 or more. The New Zealand page uses the Ministry of Health's single Obesity band rather than classes, so 30.1 and 38 both read as Obesity.
Do Asian ethnicities have different cut-offs here?
The sources say lower thresholds should be considered for people of Asian descent but give no numbers, so the page applies the standard bands. Treat a result near a boundary with care and ask your GP.
Why is my healthy range different from a friend's?
The range depends on height only. It is 18.5 to 24.9 times height in metres squared, so someone at 165 cm gets 50.4 to 67.8 kg while someone at 175 cm gets 56.7 to 76.3 kg.
Can I use the result for a child?
No. The adult bands do not apply to children and young people, and New Zealand has separate clinical guidelines for them. A GP or Plunket nurse can use those.