Free Australian calculators

Health & Fitness Calculators

Free health and fitness calculators for Australians — BMI and healthy weight, body fat, energy needs in calories and kilojoules, macros, water intake, running pace, and pregnancy and fertility dates. They use metric units by default, with imperial options, and explain the formulas behind every result.

  • 12 free calculators
  • No sign-up
  • Australian settings
  • Formulas explained

Health calculators provide general information and estimates only and are not medical advice. Speak with your GP, an Accredited Practising Dietitian, or your midwife or obstetrician before making changes, especially if you are pregnant, breastfeeding, under 18 or managing a health condition.

Most Used Health Calculators

BMI CalculatorBody mass index for adults.Open calculatorTDEE CalculatorTotal daily energy expenditure.Open calculatorDue Date CalculatorEstimate your baby's due date.Open calculatorCalorie & Kilojoule CalculatorConvert kilojoules to calories and calories to kJ.Open calculator

Body Weight & Composition Calculators

Check BMI, a healthy weight range for your height and an estimate of body fat from tape-measure readings.

3 tools
BMI CalculatorBody mass index for adults.Ideal Weight CalculatorHealthy weight range for your height.Body Fat CalculatorEstimate body fat percentage.

Calorie, Kilojoule & Nutrition Calculators

Estimate the energy your body uses, convert between calories and kilojoules, and set protein, carb, fat and water targets.

5 tools
BMR CalculatorBasal metabolic rate — calories burned at rest.TDEE CalculatorTotal daily energy expenditure.Calorie & Kilojoule CalculatorConvert kilojoules to calories and calories to kJ.Macro CalculatorProtein, carb and fat targets.Water Intake CalculatorHow much water to drink each day.

Running & Fitness Calculators

Work out running pace, finish times and splits for any distance.

1 tool
Pace CalculatorRunning pace, time and distance.

Pregnancy & Fertility Calculators

Estimate your fertile window, your baby's due date and a healthy range for weight gain week by week.

3 tools
Ovulation CalculatorEstimate your fertile window.Due Date CalculatorEstimate your baby's due date.Pregnancy Weight Gain CalculatorHealthy weight gain by week of pregnancy.

Which Calculator Do I Need?

If you want to know…Use
Is my weight in a healthy range for my height?BMI Calculator
How many calories do I burn in a day?TDEE Calculator
How many calories does my body burn at rest?BMR Calculator
How do I convert kilojoules on a food label to calories?Calorie & Kilojoule Calculator
How much protein, carbs and fat should I eat?Macro Calculator
What is my body fat percentage from my measurements?Body Fat Calculator
When is my baby due?Due Date Calculator
What pace do I need for a 5 km or marathon goal time?Pace Calculator

Health Calculators in Metric and Kilojoules

Australian food labels list energy in kilojoules, while many apps and articles use calories. The energy calculators here show both (1 kcal = 4.184 kJ), and the calorie and kilojoule calculator converts any label in either direction. Height and weight default to centimetres and kilograms, with feet, inches and pounds available.

Understanding Your Body Measurements

The BMI calculator compares your weight with your height. For most adults, a BMI of 18.5 to 24.9 falls in the healthy weight range, but BMI doesn't distinguish muscle from fat and isn't designed for children, pregnancy or very muscular people. That's why it helps to look at more than one measure.

Waist, hip and other body measurements add context. The body fat calculator uses tape-measure readings of your waist, neck and (for women) hips to estimate body fat percentage, and the ideal weight calculator shows the healthy weight range for your height using several common formulas.

Energy, Calories and Macros

Your basal metabolic rate is the energy your body uses at complete rest. The BMR calculator estimates it with the Mifflin-St Jeor equation, and the TDEE calculator multiplies it by an activity factor to estimate your total daily energy expenditure — the starting point for maintaining, losing or gaining weight. The macro calculator then splits that energy into protein, carbohydrate and fat.

These are population-based estimates. Individual needs vary, so watch how your weight and energy levels respond over a few weeks and adjust, ideally with advice from an Accredited Practising Dietitian.

Pregnancy and Fertility Dates

The due date calculator estimates your due date as 280 days (40 weeks) from the first day of your last period, or from a conception or IVF transfer date. The ovulation calculator estimates your fertile window from your cycle length, and the pregnancy weight gain calculator shows a general healthy range based on your pre-pregnancy BMI. Your midwife, GP or obstetrician will confirm dates, usually with an early ultrasound.

Frequently Asked Questions

What is a health calculator?

A health calculator turns simple measurements such as height, weight, age and activity level into useful estimates — for example body mass index, daily energy needs or a pregnancy due date. They are a quick screening and planning tool, not a diagnosis.

What does a fitness calculator measure?

Fitness calculators estimate things like daily energy expenditure, macronutrient targets, body fat percentage and running pace. Use the TDEE calculator for energy needs and the pace calculator to plan race times and training splits.

Is there a calculator for body measurements like waist and hips?

Yes. The body fat calculator uses waist, neck and hip measurements to estimate body fat percentage. For bust and underbust measurements, the bra size converter estimates a bra size and converts it between countries.

How accurate is a BMI calculator?

The BMI formula itself is exact, but BMI is only a rough guide to body fat. It can overestimate fat in muscular people and underestimate it in older adults who have lost muscle. Waist measurement and a check-up with your GP give a fuller picture.

How many kilojoules should I eat a day?

It depends on your age, sex, size and activity level. The TDEE calculator estimates your daily energy needs in both kilojoules and calories. As a reference point, food labels in Australia are based on an average adult intake of 8,700 kJ a day.

How is a pregnancy due date calculated?

Most due dates are estimated by adding 280 days to the first day of your last menstrual period, adjusted if your cycle is longer or shorter than 28 days. The due date calculator also works from a conception or IVF transfer date.

Are these calculators suitable for children or during pregnancy?

Most adult formulas, including BMI, BMR and body fat, aren't designed for children or for use during pregnancy. Children's BMI is assessed with age- and sex-specific growth charts, and pregnancy needs individual advice from your midwife, GP or obstetrician.

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Health calculators provide general information and estimates only and are not medical advice. Speak with your GP, an Accredited Practising Dietitian, or your midwife or obstetrician before making changes, especially if you are pregnant, breastfeeding, under 18 or managing a health condition.