BMI Calculator NZ 2026

Quick answer BMI is your weight in kilograms divided by your height in metres squared. Under the standard bands, 18.5 to 24.9 is the healthy range, 25 to 29.9 is overweight and 30 or above is obese. It is a screening measure, not a diagnosis.

This BMI calculator works out your Body Mass Index from your height and weight, giving you a quick screening figure that doctors and health services use to flag whether your weight sits in a healthy range for your height. Choose metric or imperial units: enter your height in metres and weight in kilograms, or your height in feet and inches and weight in stones, pounds and ounces. The calculator divides your weight by the square of your height and returns your BMI score instantly, along with the healthy weight range for your exact height, shown in kilograms or in stone, pounds and ounces depending on which units you used. It also highlights which of five categories your result falls into: underweight (under 18.5), healthy weight (18.5 to 24.9), overweight (25 to 29.9), obese (30 to 39.9) or morbidly obese (40 and over), so you can see at a glance where you stand. Use it to track changes over time, set a realistic weight target, or understand a number your doctor or gym has mentioned. BMI is a simple ratio that does not measure body fat, muscle mass or where fat is carried, so it can be misleading for athletes, older adults, pregnant women and some ethnicities. Treat the result as general information only, not a diagnosis, and talk to your doctor about what a healthy weight looks like for you.

General information, not medical advice. BMI is a rough screening measure and does not account for muscle, body composition, ethnicity, age or pregnancy. It can misclassify athletes, older adults and some ethnic groups, and it is not applied to children the same way. Talk to your doctor about what a healthy weight means for you.
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Metric Imperial
Height
m
Weight
kg
Your BMI
0.00
Less than 18.5Underweight
18.5 to 24.9Healthy weight
25 to 29.9Overweight
30 to 39.9Obese
40 and overMorbidly obese

How it works

BMI divides your weight by the square of your height. In metric units that is kilograms divided by metres squared. In imperial units the calculator converts stones, pounds and ounces to total pounds, and feet and inches to total inches, then applies the standard imperial BMI formula (weight in pounds divided by height in inches squared, multiplied by 703) so the result matches the metric score. The healthy weight range shown alongside your BMI is worked out by rearranging the same formula for the lower (18.5) and upper (24.9) bounds of the healthy band at your exact height, so you can see the actual kilograms or stones and pounds that range covers for you.

Worked example

At 1.75 metres and 70 kilograms, BMI is 70 divided by (1.75 times 1.75), which is 22.86. That falls in the healthy weight band of 18.5 to 24.9. For someone 1.75 metres tall, the healthy weight range works out to about 56.7kg to 76.3kg, so 70kg sits comfortably inside it.

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Frequently asked questions

What is the BMI Calculator NZ 2026?

Calculate your BMI (Body Mass Index) and see your healthy weight range. Uses WHO BMI categories with metric and imperial inputs. Includes BMI interpretation for adults.

Is the BMI Calculator NZ 2026 free to use?

Yes. The BMI Calculator NZ 2026 is free to use on Calculate.co.nz, with no sign-up, paywall or account required.

Is the BMI Calculator NZ 2026 made for New Zealand?

Yes. It is built for use in New Zealand. Results are general information for education only and are not medical advice; discuss your weight and health with your doctor.