What does this calorie calculator do?

This calculator estimates how many Calories (kilocalories) you burn in a day based on your age, height, weight, gender, and activity level. It first calculates your Basal Metabolic Rate (BMR) – the energy your body needs at rest – and then multiplies it by an activity factor to estimate your Total Daily Energy Expenditure (TDEE).

You can use the maintenance value as a reference point, then choose a modest deficit if you want to lose fat or a small surplus if you want to build muscle or gain weight. The result table shows example targets for different speeds of change.

Typical daily calorie ranges

Exact needs vary a lot between people, but the table below shows rough maintenance ranges for generally healthy adults with average heights:

If your goal is fat loss, many guidelines suggest aiming for about 0.5–1.0 lb (0.25–0.5 kg) per week. Faster loss usually demands a larger deficit and is harder to maintain long term.

Calories, weight and health

If you consistently eat more than you burn

• Body weight usually increases over time, mostly as extra fat mass.
• Risk can rise for conditions such as type 2 diabetes, high blood pressure and heart disease.
• Gaining muscle deliberately still needs a surplus, but usually only a few hundred calories per day.

If you consistently eat less than you burn

• Body weight normally goes down over weeks and months.
• Very large deficits may cause fatigue, hunger, muscle loss and slower metabolism.
• Most people do best with a moderate, sustainable deficit plus enough protein and resistance exercise.

If you have a lot of weight to lose, live with a long-term health condition, or have a history of disordered eating, it is important to work with a qualified professional rather than dieting alone.

Formulas used in this calculator

BMR (Mifflin–St Jeor equation)

Weight is in kilograms, height in centimeters, age in years.

Men: BMR = 10 × weight + 6.25 × height − 5 × age + 5

Women: BMR = 10 × weight + 6.25 × height − 5 × age − 161

Activity factors (TDEE)

The daily calorie estimate to maintain weight (TDEE) multiplies BMR by an activity factor:

• Sedentary: 1.2 (little or no exercise)
• Light: 1.375 (light exercise 1–3 days/week)
• Moderate: 1.55 (exercise 3–5 days/week)
• Active: 1.725 (hard exercise 6–7 days/week)
• Very active: 1.9 (physical job or intense training)

Sample calorie targets

Once maintenance calories are estimated, the calculator subtracts or adds Calories to suggest targets. For example, a deficit of about 500 kcal/day is often used as a rough starting point for losing around 1 lb (0.45 kg) per week, while a surplus of 200–400 kcal/day is typical for lean muscle gain.

Food energy, Calories and kilojoules

On nutrition labels in the United States, energy is usually shown as Calories, which in scientific terms are actually kilocalories (kcal). Many other countries list energy in both Calories and kilojoules (kJ). The two describe the same thing: how much usable energy your body can get from food.

The conversion between the units is fixed. One kilocalorie is equal to approximately 4.184 kilojoules. That means a 250 kcal snack contains about 1,046 kJ. Likewise, a food labeled as 2,100 kJ provides roughly 502 kcal.

In day-to-day nutrition planning, most people in the U.S. find it easier to think in Calories, because portion sizes, diet guidelines, and menus typically use kcal. If you read research papers or international labels, you may see values only in kJ; in those cases, a quick conversion helps keep your daily totals consistent.

The Food Energy Converter above is designed for this practical use: enter the number you see on a package or in a meal plan, change the direction if needed, and you instantly get the equivalent value in the other unit. This lets you compare products from different regions, interpret scientific charts, or match app settings that prefer one unit over the other without doing the math by hand.