Health & medical New Zealand
BMR and TDEE Calculator New Zealand
Your body burns energy even at rest, and more when you move. This calculator estimates your basal metabolic rate (BMR) and your total daily energy expenditure (TDEE) from your age, height, weight and activity level, in kilojoules, the unit on food labels here, and in calories.
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Daily energy use
βBMR in kJ
β
BMR in calories
β
Daily use in calories
β
Energy per hour at rest
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The working
An estimate, not medical advice. General information only, not medical advice. Everyone is different, so speak to a doctor, dietitian or other health professional before you change your diet or exercise.
How do I calculate my daily energy needs?
Work out your BMR with the Mifflin-St Jeor equation, then multiply by an activity factor. A 35-year-old man at 180 cm and 80 kg has a BMR of 1,755 calories (7,343 kJ). With moderate activity (x1.55) that is about 2,720 calories or 11,382 kJ a day.
BMR and TDEE
BMR is the energy needed for basic life processes with no activity at all: breathing, circulation, temperature control and cell repair. It makes up the largest part of daily energy use. TDEE adds the energy for movement, exercise and digesting food.
The activity factor is the biggest source of error. Most people overestimate how active they are, so choose a lower level if you are unsure.
Using the result
Eating around your TDEE tends to keep your weight steady, while eating consistently more or less changes it over time. Big changes are best made gradually and with advice from a doctor or dietitian, particularly if you have a health condition, are pregnant or are under 18. Use the nutrition panel on food packaging, which lists energy in kJ per serve and per 100 g.
To convert between units, use the kJ to calories converter.
How this is calculated
The rule, step by step, so you can check any figure by hand.
BMR for men = 10 Γ weight (kg) + 6.25 Γ height (cm) β 5 Γ age + 5BMR for women = 10 Γ weight (kg) + 6.25 Γ height (cm) β 5 Γ age β 161TDEE = BMR Γ activity factor (1.2 to 1.9)kilojoules = calories Γ 4.184energy per hour at rest = BMR Γ· 24
The Mifflin-St Jeor equation is one of the most widely used estimates of resting energy use and is usually within about ten percent for healthy adults. Individual metabolism varies with muscle mass, genetics, medical conditions and medicines, so treat the result as a starting point.
Food labels here show energy in kilojoules, so the result is given in kJ first. A moderately active adult often uses between 8,000 and 12,000 kJ a day; the calculator shows where you sit.
A worked example
A 35-year-old man, 180 cm tall, 80 kg, exercising moderately 3 to 5 days a week.
- BMR (calories)1,755
- BMR (kJ)7,343
- Activity factor1.55
- TDEE (calories)2,720
- TDEE (kJ)11,382
About 11,382 kJ a day.
Eating around this amount tends to keep weight steady.
Why estimates differ
Other equations give figures a few hundred kJ apart, and wearable devices use their own models. Compare how your weight changes over a few weeks against what you eat, and adjust from there.
Who it is not for
This tool is for healthy adults. It is not suitable for children, pregnancy, breastfeeding or medical conditions affecting metabolism.
What this calculator does not do
- Healthy adults only
- Estimate within about ten percent
- Activity level is your own judgement
- Not medical or dietary advice
Common questions
What is BMR?
The energy your body uses at rest to keep you alive.
What is TDEE?
Your total daily energy use, including activity.
Why are results in kilojoules?
Food labels here use kJ, with calories shown as a conversion.
How accurate is it?
Usually within about ten percent for healthy adults.
Can I use it while pregnant?
No. Speak to your midwife or doctor about energy needs.
Where these numbers come from
- Ministry of Health β ManatΕ« Hauora Government health information
Method last reviewed 2026-10-28 This calculator uses fixed rules rather than rates that change, and its method is re-checked against the sources above at least once a year. Out of date? Tell us and we will fix it.
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