Calorie Calculator

The Calorie Calculator estimates your daily energy needs in three layers: your basal metabolic rate (BMR), your maintenance calories (TDEE), and five weight-goal targets from losing 0.5 kg per week to gaining 0.5 kg per week. Enter age, sex, height, weight, and activity level to get the numbers in seconds.

How the Calculation Works

The calculation is a three-step chain.

1. BMR via Mifflin-St Jeor. 10 × weight(kg) + 6.25 × height(cm) − 5 × age, then +5 for men or −161 for women. This is the energy you would burn at complete rest.
2. TDEE. BMR is multiplied by one of five standard activity factors: 1.2 (sedentary), 1.375 (light), 1.55 (moderate), 1.725 (active), or 1.9 (very active).
3. Goal targets. Each goal shifts TDEE by a fixed daily amount. The tool assumes roughly 7,700 kcal per kilogram of body fat, so ±0.5 kg/week becomes ±500 kcal/day and ±0.25 kg/week becomes ±250 kcal/day. Goals never drop below zero.

The five activity multipliers are fixed and well known, which makes the table worth reading before you pick:

Level	Multiplier	What it describes
Sedentary	1.2	Desk work, little deliberate exercise
Light	1.375	Light exercise 1–3 days a week
Moderate	1.55	Moderate exercise 3–5 days a week
Active	1.725	Hard exercise 6–7 days a week
Very active	1.9	Physical job plus hard daily training

The multiplier is applied to BMR, not added, so the difference compounds with body size. That is why two people with the same stated activity level can have very different maintenance calories.

Worked Example: One Person, Three Activity Levels

Take a 30-year-old woman, 165 cm and 65 kg.

BMR = 10×65 + 6.25×165 − 5×30 − 161 = 650 + 1031.25 − 150 − 161 = 1370 kcal/day

Her maintenance intake then depends entirely on activity:

Activity	Multiplier	TDEE	Target at −500 kcal/day
Sedentary	1.2	1644	1144
Moderate	1.55	2124	1624
Very active	1.9	2603	2103

The same person’s “lose 0.5 kg per week” target ranges from 1,144 to 2,103 kcal depending only on the activity answer. That is why the honesty of that dropdown matters more than any other field.

For contrast, take a 40-year-old man, 180 cm and 90 kg. His BMR is 10×90 + 6.25×180 − 5×40 + 5 = 900 + 1125 − 200 + 5 = 1830 kcal/day. At moderate activity that is a TDEE of 1830 × 1.55 = 2837, so his maintenance is roughly 2,837 kcal and his −0.5 kg/week target is about 2,337 kcal. The absolute numbers differ from the first example, but the mechanics are identical: BMR, then multiplier, then a fixed shift.

Reading the Goal Cards

Five cards are shown. The first two subtract 500 and 250 kcal for faster and slower weight loss; the middle card equals maintenance; the last two add 250 and 500 kcal for lean gaining. The maintain card is highlighted. A 500 kcal daily deficit corresponds to about half a kilogram per week, and 250 to a quarter kilogram — slower changes are generally easier to sustain and preserve more muscle when cutting.

Scope, Limits, and Safety

This tool produces statistical estimates, not medical advice, and it cannot diagnose or treat anything. The equation was derived for healthy adults and was not designed for children, pregnant or breastfeeding people, competitive athletes, or people with thyroid, kidney, or eating disorders. It does not account for medication, menstrual-cycle water shifts, or metabolic adaptation during a long diet, during which real expenditure can drift 10–15% below the prediction. A pound or more of week-to-week weight fluctuation from sodium and hydration is normal and can easily mask the true trend. The 7,700 kcal-per-kilogram figure is itself an approximation: it describes the energy in a kilogram of fat tissue, but early weight loss also includes water and glycogen, so the first week or two often moves faster than the math predicts. Use the result as a hypothesis: follow it for two to three weeks, compare against your actual weight trend, and adjust. If a target requires eating very little, if you have a medical condition, or if you are unsure, consult a qualified professional rather than trusting a web calculator.

Choosing an Activity Level Honestly

The five levels describe weekly patterns, not today’s workout. Sedentary is desk work with little deliberate movement. Light is light exercise one to three days a week. Moderate is moderate exercise three to five days a week. Active is hard exercise six to seven days a week. Very active is physical labor plus hard daily training. When two levels feel plausible, choose the lower one; the multiplier is an average, and a single ambitious gym session does not move it.

Turning Calories into Macros

Once you have a calorie target, the next step is splitting it into protein, carbohydrate, and fat. The Macro Calculator converts the calories into grams for each macro based on your goal, which is more actionable than a single daily number when you are planning meals.

Related Tools

• Macro Calculator
• BMI Calculator
• Body Fat Calculator
• Water Intake Calculator