Calorie Calculator – How Many Calories Do You Need?
Find your daily calorie needs in seconds. This free calorie calculator uses the Mifflin-St Jeor equation — the formula dietitians rate most accurate — to work out your BMR and TDEE, then shows the daily targets for losing, maintaining or gaining weight, with a protein, carb and fat split for each.
Calculate Your Daily Calories
| BMR (calories burned at complete rest) | – |
| Lose ~1 lb/week (deficit of 500) | – |
| Lose ~0.5 lb/week (deficit of 250) | – |
| Maintain your weight | – |
| Gain ~0.5 lb/week (surplus of 250) | – |
| Gain ~1 lb/week (surplus of 500) | – |
At maintenance, a balanced 30% protein / 40% carbs / 30% fat split is about –. Safety floor: eating below 1,200 kcal/day (women) or 1,500 kcal/day (men) is not recommended without medical supervision —
How to Use the Calorie Calculator
Enter your sex, age, weight and height, then pick the activity level that honestly matches a normal week — not your best week. That honesty matters more than any other input, because the activity multiplier is the biggest source of error in every calorie calculator. If you work a desk job and train three evenings a week, you are lightly to moderately active, even though the training itself feels hard. Press Calculate My Calories and you get two headline numbers: your BMR, the calories your body burns doing nothing at all, and your TDEE, the maintenance level at which your weight stays stable. Everything else on the results table is simple arithmetic on the TDEE.
The targets use the standard, evidence-based deficits and surpluses: eating about 500 kcal below maintenance produces roughly one pound of fat loss per week, 250 below produces about half a pound, and the mirror-image surpluses gain at the same gentle rates. Faster is rarely better — deficits beyond 500 kcal a day cost muscle, energy and adherence, which is why this calculator does not offer them.
The Mifflin-St Jeor Equation
Of the equations used to estimate resting metabolism, the Mifflin-St Jeor equation, published in 1990, has repeatedly tested as the most accurate for the general population — within about 10% of measured values for most adults, and more reliable than the older Harris-Benedict formula it replaced. It needs only your sex, weight, height and age:
Your TDEE is then your BMR multiplied by an activity factor that accounts for everything else you do — walking, working, training, fidgeting:
| Activity level | Multiplier | Typical day |
|---|---|---|
| Sedentary | × 1.2 | Desk job, driving, no structured exercise |
| Lightly active | × 1.375 | Light exercise 1–3 days a week, or a job with some walking |
| Moderately active | × 1.55 | Training 3–5 days a week |
| Very active | × 1.725 | Hard training 6–7 days a week |
| Extra active | × 1.9 | Physical labour plus daily training, or elite athletes in season |
Worked Example
Take a 30-year-old man, 80 kg, 180 cm, who trains four days a week. His BMR is (10 × 80) + (6.25 × 180) − (5 × 30) + 5 = 800 + 1,125 − 150 + 5 = 1,780 kcal. Multiplied by 1.55 for his activity, his maintenance TDEE is 2,759 kcal a day. To lose about a pound a week he eats near 2,259 kcal; to gain slowly, near 3,009 kcal. At maintenance, the 30/40/30 macro split works out to roughly 207 g protein, 276 g carbs and 92 g fat — protein is deliberately set generously, because adequate protein is what protects muscle while you lose fat, and it is the macro most people under-eat.
Two practical notes before you treat the targets as a plan. Protein is set first in the split — 30% of calories — because it drives satiety and protects muscle in a deficit; if your calculated protein lands below about 1.6 g per kilogram of body weight while dieting, favour protein-rich foods first and let the carb and fat numbers flex around it. And weigh the trend, not the day: body weight swings by a kilogram or more with water, salt and meal timing, so judge your intake by the average of two to three weeks, never by a single morning.
Limitations — Read This Before Dieting on a Number
Every calorie equation is an estimate, and this one is honest about it: individual metabolic rates vary by roughly ±10% around any formula, because muscle mass, genetics, hormones, sleep and medications all move the true figure. Treat the result as a starting point, hold your intake steady for two to three weeks, and adjust by 100–200 kcal based on what your weight actually does — that feedback loop beats any equation. The 500-kcal-equals-a-pound rule is also an approximation that flattens out over time as your body adapts. This calculator is general information, not medical advice: it is not designed for children, pregnancy, eating-disorder recovery, or medical conditions such as diabetes or thyroid disease, and it will not offer targets below the recognised safety floors without flagging them. If in doubt, a registered dietitian can measure what a formula can only estimate.
Guides for This Tool
Frequently Asked Questions
How accurate is this calorie calculator?
What is the difference between BMR and TDEE?
How many calories should I eat to lose weight?
Why did my calorie needs come out higher than expected?
Can I gain muscle on the gaining targets?
How often should I recalculate my calories?
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Find this calculator and the rest of the health toolkit in the Health tools category.