Calorie & TDEE Calculator
Calculate your BMR and Total Daily Energy Expenditure using Mifflin-St Jeor — then get calorie targets for weight loss, maintenance, and muscle gain with a full macro split.
Calculating...
Enter your details above to calculate your BMR, TDEE, and daily calorie goals.
What Is a TDEE Calculator?
A TDEE calculator estimates your Total Daily Energy Expenditure — the total number of calories your body burns in a day, combining your resting metabolism with your physical activity. TDEE is the single most important number for nutrition planning: eating below it leads to fat loss, eating above it leads to weight gain, and eating at it maintains your current weight.
This calculator uses the Mifflin-St Jeor equation (1990) to compute your Basal Metabolic Rate, then multiplies it by an activity factor to give your TDEE. It also shows your BMR from the classic Harris-Benedict formula so you can compare both estimates and understand the range of uncertainty.
How to Calculate Your BMR (Basal Metabolic Rate)
Your Basal Metabolic Rate (BMR) is the number of calories your body needs to perform essential functions at complete rest — breathing, circulation, cell repair, and temperature regulation. It accounts for 60–75% of total daily calorie expenditure for most people.
Gather your inputs
Weight (kg or lbs), height (cm or ft/in), age, and biological sex
Imperial inputs are automatically converted to metric for the formula.
Apply Mifflin-St Jeor
Male: BMR = (10 × kg) + (6.25 × cm) − (5 × age) + 5
Female: BMR = (10 × kg) + (6.25 × cm) − (5 × age) − 161
The only difference between male and female is the final constant (+5 vs −161).
Multiply by activity factor
TDEE = BMR × activity multiplier
Activity multipliers range from 1.2 (sedentary) to 1.9 (extremely active physical job).
Worked Example
30-year-old male, 80 kg, 178 cm, sedentary (×1.2)
BMR = (10 × 80) + (6.25 × 178) − (5 × 30) + 5
BMR = 800 + 1,112.5 − 150 + 5
BMR = 1,767.5 ≈ 1,768 kcal/day
TDEE = 1,768 × 1.2
TDEE = 2,122 kcal/day
Mifflin-St Jeor vs Harris-Benedict — Which Formula Is More Accurate?
Both formulas estimate BMR from height, weight, age, and sex. Research published in the Journal of the American Dietetic Association found that Mifflin-St Jeor predicted resting metabolic rate within 10% of measured values for more people than Harris-Benedict, making it the preferred formula in clinical dietetics today.
Mifflin-St Jeor (1990) — Recommended
Male: BMR = (10 × kg) + (6.25 × cm) − (5 × age) + 5
Female: BMR = (10 × kg) + (6.25 × cm) − (5 × age) − 161
More accurate for modern populations. Preferred by most registered dietitians.
Harris-Benedict Revised (Roza & Shizgal, 1984) — Classic
Male: BMR = 88.362 + (13.397 × kg) + (4.799 × cm) − (5.677 × age)
Female: BMR = 447.593 + (9.247 × kg) + (3.098 × cm) − (4.330 × age)
Published in 1918, revised 1984. Tends to overestimate BMR by 5–15% for obese individuals.
TDEE Formula
TDEE = BMR × Activity Multiplier
This calculator uses the Mifflin BMR for TDEE. Both BMR values are displayed so you can see the spread.
How Activity Level Affects Your Daily Calorie Needs
The activity multiplier is the biggest variable in TDEE. The difference between sedentary and extra active is a multiplier of 1.2 vs 1.9 — a 58% difference in estimated daily calorie needs for the same body. Choosing the wrong activity level is one of the most common reasons calorie estimates feel inaccurate.
| Activity Level | Who it fits | Multiplier |
|---|---|---|
| Sedentary | Desk job, no planned exercise | 1.200 |
| Lightly active | Light exercise 1–3 days/week | 1.375 |
| Moderately active | Moderate exercise 3–5 days/week | 1.550 |
| Very active | Hard exercise 6–7 days/week | 1.725 |
| Extra active | Very hard training or physical labour job | 1.900 |
Tip: most office workers overestimate their activity level. If unsure, choose one level lower and adjust after 2–3 weeks of tracking.
Calorie Targets for Weight Loss, Maintenance, and Muscle Gain
Once you know your TDEE, adjusting your intake to meet a specific goal is straightforward. One kilogram of body fat contains approximately 7,700 kcal. To lose one kilogram per week, you need a weekly deficit of 7,700 kcal — or a daily deficit of roughly 1,100 kcal. In practice, most people target a 500–1,000 kcal/day deficit for sustainable, healthy fat loss without muscle loss.
Weight Loss
Eat 500–1,000 kcal below TDEE. A 500 kcal/day deficit produces ~0.5 kg/week fat loss, considered moderate and sustainable. Aggressive deficits above 1,000 kcal risk muscle breakdown. Never drop below 1,200 kcal (female) or 1,500 kcal (male) without medical supervision.
Maintenance
Eating at your TDEE keeps weight stable. This is the baseline from which you adjust up or down. Use a food tracking app for 2–3 weeks to see whether your actual weight stays stable — real TDEE varies by individual metabolism, and tracking calibrates the estimate.
Muscle Gain
A surplus of 300–500 kcal/day (a "lean bulk") supports muscle growth while limiting fat gain. Beginners can sometimes gain muscle in a slight deficit (body recomposition), but an established training programme with adequate protein (1.6–2.2 g/kg bodyweight) is essential regardless of calorie target.
How to Use Your Macros
This calculator uses a balanced 40% carbohydrate / 30% protein / 30% fat split as a starting point. This distribution is appropriate for most active people. Your ideal macro ratio depends on your goals and preferences — athletes may shift toward higher carbs, low-carb dieters toward more fat.
| Macro | Calories / gram | Primary role |
|---|---|---|
| Carbohydrates | 4 kcal/g | Primary fuel for high-intensity exercise and brain function |
| Protein | 4 kcal/g | Muscle repair and growth, enzyme production, immune function |
| Fat | 9 kcal/g | Hormone production, fat-soluble vitamin absorption, cell membrane integrity |
Protein is the most important macro to track precisely — aim for 1.6–2.2 g per kg of bodyweight daily to preserve or build muscle, especially in a calorie deficit. Carbs and fat can be distributed more flexibly within your calorie budget.
Calorie & TDEE Calculator FAQ
What is TDEE?
TDEE stands for Total Daily Energy Expenditure — the total number of calories your body burns in 24 hours, including your resting metabolism, the energy cost of digesting food (thermic effect of food, ~10% of calories), and all physical activity. It is the most useful single number for nutrition planning because eating at, above, or below TDEE directly determines whether you lose fat, maintain weight, or gain mass.
What is the difference between BMR and TDEE?
BMR (Basal Metabolic Rate) is what your body burns at complete rest — just to stay alive. TDEE is BMR multiplied by your activity level to account for all movement throughout the day. A sedentary person's TDEE is about 20% above their BMR; a very active person's TDEE can be 70–90% above their BMR.
How accurate is the Mifflin-St Jeor formula?
A study comparing five BMR equations found Mifflin-St Jeor most accurately predicted measured resting metabolic rate for both normal-weight and obese individuals, with about 82% of estimates falling within 10% of the true value. No formula is perfect — actual metabolic rate varies by genetics, muscle mass, hormones, and health status. Use the result as a calibration starting point, then adjust over 2–4 weeks based on real weight-change data.
How many calories should I eat to lose weight?
A deficit of 500 kcal/day below your TDEE produces approximately 0.5 kg of fat loss per week, which is widely considered the healthiest sustainable rate. A 1,000 kcal/day deficit produces roughly 1 kg/week. Going beyond 1,000 kcal/day increases the risk of muscle loss, nutritional deficiencies, and metabolic adaptation. The tool enforces a minimum floor of 1,200 kcal (female) / 1,500 kcal (male) for safety.
How many calories should I eat to gain muscle?
A modest calorie surplus of 300–500 kcal/day above TDEE — sometimes called a "lean bulk" — provides the energy needed for muscle protein synthesis without excessive fat gain. Protein intake of 1.6–2.2 g/kg of bodyweight and a structured resistance-training programme are more important than the size of the surplus. Beginners may see muscle gains even at maintenance calories during the first few months of training.
Why does my TDEE decrease as I age?
BMR declines with age primarily because people progressively lose lean muscle mass — a process called sarcopenia — unless they engage in resistance training. Muscle tissue is metabolically active and burns more calories at rest than fat tissue. Hormonal changes (declining testosterone, oestrogen, and thyroid hormone) also reduce metabolic rate. The Mifflin formula's age coefficient (−5 per year) captures this trend, though individual rates of metabolic decline vary significantly.
What is a calorie deficit and how big should mine be?
A calorie deficit is the difference between the calories you consume and the calories you burn. A deficit of 3,500 kcal equals approximately 0.45 kg (1 lb) of fat loss, though this is an approximation — real fat loss rate depends on water retention, muscle preservation, and metabolic adaptation. A deficit of 500 kcal/day is widely cited as the sweet spot: meaningful progress (~0.5 kg/week) without triggering significant hunger, muscle loss, or the metabolic slowdown caused by very-low-calorie diets.
Do macros matter or just total calories?
Total calories determine whether you gain or lose weight. Macros determine body composition — the ratio of fat to muscle in that weight change. High protein intake (1.6–2.2 g/kg) significantly improves muscle retention during fat loss and muscle gain during a surplus. Carbohydrate and fat ratios are more flexible for most people, but adequate fat (≥0.5 g/kg) is essential for hormone health. The 40/30/30 split in this tool is a practical, balanced starting point.
Related Calculators
BMI Calculator
Body Mass Index with WHO category and healthy weight range.
Percentage Calculator
Calculate percent of a number, percent change, and more.
Standard Deviation Calculator
Measure spread and variance for any dataset.
Compound Interest Calculator
Future value, total interest, and year-by-year growth.
IQR Calculator
Quartiles, outliers, and box plot for any dataset.
Mean Median Mode Calculator
Descriptive statistics for any list of numbers.