BMR & calorie calculator
Calculate BMR, TDEE and goal-based calorie targets.
Based on the Mifflin-St Jeor equation. BMR is the calories burned at rest; TDEE is your total daily energy expenditure including activity. For weight loss, eating about 300–500 kcal below TDEE is a common recommendation. For reference only; individual results vary.
Nutrition labels are built around a 2,000 kcal day, but that figure is a packaging convention rather than anything about you. What your own body uses depends on your size, age, and how much you move. This calculator gives two numbers: what you would burn lying still all day, and a working estimate of what you actually burn once activity is counted.
How it works
What you enter
| Field | Notes |
|---|---|
| Sex | Male or female — the equation uses a different constant for each |
| Age | In years |
| Height | In centimetres |
| Weight | In kilograms |
| Activity level | Five bands, from sedentary to very active |
The equation behind it
This tool uses Mifflin-St Jeor, the formula most commonly recommended for healthy adults:
Men: BMR = (10 × kg) + (6.25 × cm) − (5 × age) + 5
Women: BMR = (10 × kg) + (6.25 × cm) − (5 × age) − 161
A 30-year-old man of 175 cm and 70 kg comes to 700 + 1,093.75 − 150 + 5 = about 1,649 kcal. That is the resting figure — the energy spent on breathing, circulation, temperature, and cell repair while doing nothing at all.
From BMR to TDEE
Total daily energy expenditure multiplies BMR by an activity factor:
| Level | Factor |
|---|---|
| Sedentary — little or no exercise | 1.2 |
| Light — 1–3 days a week | 1.375 |
| Moderate — 3–5 days a week | 1.55 |
| Active — 6–7 days a week | 1.725 |
| Very active — physical job or athlete | 1.9 |
The same 1,649 kcal BMR at a moderate 1.55 gives roughly 2,556 kcal a day.
How much to trust it
This is a population estimate, and individuals land either side of it — typically within about 10%. The equation knows nothing about body composition, so a muscular person is usually underestimated and a person carrying more fat at the same weight overestimated. Thyroid conditions, medication, pregnancy, and breastfeeding all shift the figure too. Use it as a starting point to adjust from, and talk to a doctor or a registered dietitian before making significant changes to how you eat.
Terms explained
- BMR
- Basal metabolic rate — the energy your body uses at complete rest just to keep functioning. It typically accounts for the largest share of daily expenditure.
- TDEE
- Total daily energy expenditure — BMR plus everything else: movement, exercise, and digestion.
- Activity factor
- The multiplier applied to BMR to reflect how much you move. Choosing one band too high is the most common source of an inflated TDEE.
- Mifflin-St Jeor
- A 1990 equation for estimating BMR from weight, height, age and sex, generally found more accurate for modern adults than the older Harris-Benedict formula.
- Calorie deficit
- Eating less energy than you expend. A moderate deficit is the usual basis of gradual weight loss.
Frequently asked questions
What is the difference between BMR and TDEE?
BMR is what you would burn spending the entire day at rest — the baseline cost of staying alive. TDEE adds everything on top: walking, work, exercise, and the energy used digesting food. TDEE is the figure to compare against what you eat; BMR on its own is well below what almost anyone actually needs.
Which activity level should I choose?
Pick the one that matches a typical week rather than your best week. Desk work with a couple of gym sessions is light to moderate, not active. Overstating this band is the usual reason an estimate comes out too high, so when you are between two options the lower one tends to be closer.
How many calories should I eat to lose weight?
Weight loss generally requires eating below TDEE, and a moderate deficit of a few hundred calories is the commonly cited approach for a gradual, sustainable rate. Very low intakes are a different matter and are not something to set from a calculator — a doctor or registered dietitian can advise on a target that fits your health and circumstances.
Why doesn't the calculator ask about body fat?
Mifflin-St Jeor works from height, weight, age and sex only, which is what makes it easy to use but also where its error comes from. Two people of identical weight can have quite different resting rates depending on muscle mass. Formulas such as Katch-McArdle use lean body mass instead, but they need a body fat measurement to work.
Is this accurate enough to rely on?
It is an estimate, not a measurement — most people fall within roughly 10% of it, but some sit further out. The practical approach is to use the number as a starting point, track what actually happens over a few weeks, and adjust. Anyone with a medical condition affecting metabolism should treat the figure with extra caution and seek professional advice.
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