Calorie Calculator

This calorie calculator estimates two numbers from your sex, age, height, weight and daily activity level. The first is your basal metabolic rate (BMR), the energy your body needs at complete rest to keep you alive. The second is your total daily energy expenditure (TDEE), which adds your everyday activity on top. Both are formula-based estimates, not medical test results. The tool does not produce a weight-loss or muscle-gain meal plan and does not tell you what to eat. All calculations run in your browser.

How to use it

1. Click Female or Male at the top. The two formulas differ by a constant.
2. Fill in Age, Height (cm) and Weight (kg). The defaults are 28 years, 165 cm, 55 kg, female, light activity.
3. Under 'Daily activity level', choose the option closest to your typical week. There are five: Sedentary / almost no exercise, Light activity (exercise 1–3 days a week), Moderate activity (3–5 days), High activity (6–7 days), and Very high activity (physical labor plus intense training).
4. The page immediately shows BMR and TDEE in kcal/day, rounded to whole numbers. If any field is empty, zero or not a number, you see 'Please enter valid age, height, and weight'.

How it is calculated, with examples (run through the tool's own formula)

BMR uses the Mifflin-St Jeor equation. For men: 10 x weight (kg) + 6.25 x height (cm) - 5 x age + 5. For women: 10 x weight + 6.25 x height - 5 x age - 161. TDEE is BMR times the activity multiplier, and the five multipliers are 1.2, 1.375, 1.55, 1.725 and 1.9. For a 28-year-old woman, 165 cm, 55 kg, light activity, BMR is about 1280 kcal/day and TDEE about 1760 kcal/day. For a 35-year-old man, 175 cm, 70 kg, BMR is about 1624 kcal/day; with moderate activity (1.55) TDEE is about 2517, and with sedentary (1.2) it is about 1949. As you can see, the activity setting alone moves the result by hundreds of kilocalories for the same person, so choose honestly.

Limits and known quirks

• Only one equation is offered (Mifflin-St Jeor). There is no switch to Harris-Benedict or to Katch-McArdle, which uses body fat percentage, and no body fat input, so the estimate is less reliable for people with unusually high muscle mass or body fat.
• The tool outputs maintenance calories (TDEE) only. It does not compute a 'cutting' or 'bulking' intake. If you adjust from TDEE, do it carefully and preferably under professional guidance.
• The age field is labeled 0 to 120, but the equation was developed for adults. Results are of limited use for children, teenagers, pregnant or breastfeeding women, and people with conditions that affect metabolism.
• Sex is limited to Female or Male, and the formula uses only these two constants.
• Activity multipliers are a rough classification of lifestyle, not your actual exercise burn. Two people who both exercise 3 to 5 days a week can burn very different amounts.
• If extreme inputs would make BMR negative, it is clamped to 0 rather than shown as a negative number.
• Results are rounded to whole kcal, which does not mean they are accurate to within a calorie or two. They are not a personal medical measurement.

What is the difference between BMR and TDEE?

BMR is the energy needed for breathing, heartbeat, body temperature and other basic functions while lying still and awake. TDEE multiplies BMR by an activity factor to include walking around, work and exercise, so it is closer to what you actually burn in a day. If your goal is to maintain weight, eating roughly your TDEE is the idea; weight tends to fall or rise only when intake stays below or above it over time.

Why does my smartwatch or body-fat scale show a different number?

Because they measure differently. This tool uses a statistical formula based only on age, height, weight and sex, whereas wearables and smart scales use their own sensor data and proprietary algorithms. Differences of tens to hundreds of kilocalories between sources are common, and no single one is universally right. Treat any figure as a range and calibrate it against how your weight actually changes over a few weeks.

How much should I eat to lose weight?

This tool does not make that decision for you. TDEE is only a baseline for maintaining weight. How much to cut safely depends on your health, current weight and the pace you aim for, and is best discussed with a doctor or registered dietitian. If you want calories for specific foods, the Food Calorie Table on this site can help.

How do I choose the activity level?

Pick based on your real average week. Most office workers, even with a few gym visits, are closer to Light or Moderate. Very high activity is meant for people with physically demanding work who also train hard. If you are unsure, take the lower option, which is less likely to overestimate.

Privacy and processing

The sex, age, height and weight you enter are used only for the formula inside your browser. Nothing is sent to a server or stored. Reloading the page brings every field back to its default.