Calorie Calculator
Enter your age, sex, height, weight, and activity level to get your total daily energy expenditure (TDEE) and calorie targets for losing, maintaining, or gaining weight. Choose between three BMR formulas, see a protein, carb, and fat macro split, get a 7-day zigzag plan, estimate the time to reach a target weight, and optionally price your daily food.
Formula
Worked example
BMR 1,650 kcal × 1.55 (moderately active) ≈ 2,558 kcal/day to maintain; about 2,058 to lose ~0.5 kg/week, splitting into roughly 154 g protein, 206 g carbs and 69 g fat.
How the calculator works
Your basal metabolic rate (BMR), the calories your body burns at complete rest just to breathe and circulate blood, is estimated from your age, sex, height, and weight. You can pick from three published formulas: Mifflin-St Jeor (the default, most accurate for most adults), the Revised Harris-Benedict equation, or Katch-McArdle, which uses your body fat percentage and is more accurate for lean, athletic people. BMR is then multiplied by an activity factor, from 1.2 for a sedentary lifestyle up to 1.9 for an extremely active one, to give your TDEE, the total calories you need each day. Eat at TDEE to maintain, below it to lose, and above it to gain.
Weight goals and the 3,500 kcal rule
A pound of body fat stores roughly 3,500 kilocalories, and a kilogram about 7,700, so a daily deficit of 500 kcal works out to about 0.5 kg (1 lb) of loss per week. The calculator shows several targets at once: lose or gain 0.25, 0.5, and 1 kg per week, alongside your maintenance number. Aggressive targets are flagged in the insight panel: any plan that drops you below roughly 1,200 kcal (women) or 1,500 kcal (men), or that asks for more than a 1,000 kcal daily deficit, is unsafe without medical supervision. Enter a target weight and the calculator estimates how many weeks it would take at your chosen pace.
Macros, zigzag cycling, and food cost
Beyond a single calorie number, the calculator splits your goal target into grams of protein, carbohydrate, and fat using a balanced 30/40/30 ratio (protein and carbs are 4 kcal per gram, fat is 9). The 7-day zigzag plan varies calories across the week, higher on some days and lower on others, while keeping the weekly average on target; many people find this easier to stick to and it can blunt the metabolic slowdown of a flat diet. Switch the output to kilojoules if you prefer SI units, and turn on the optional cost estimate to multiply your daily calories by a price per 100 kcal for a rough daily food budget.
What affects your result
Age lowers BMR because lean muscle mass tends to decline over time, which is why every equation subtracts an age term. Body weight and height are the two largest drivers: a taller or heavier person needs more energy at rest. Activity level has an outsized effect; moving from sedentary (1.2x) to moderately active (1.55x) can add several hundred kilocalories to your daily target, so be honest about a typical week rather than your best one. Hormonal conditions such as hypothyroidism, certain medications, and significant changes in body composition can also shift true energy needs in ways no equation captures.
Limitations and when to consult a professional
Prediction equations were derived from healthy adults and may be less accurate for people with obesity, sarcopenia, or chronic illness; studies typically report mean errors of roughly 10 to 15% versus measured resting metabolic rate. The 3,500 kcal per pound rule is a useful approximation, but real weight change slows as the body adapts, so track your weight trend over two to three weeks and adjust. This calculator provides a general estimate for informational purposes only and is not a substitute for advice from a registered dietitian or physician. If you are pregnant or breastfeeding, have a medical condition, or have a history of disordered eating, seek guidance from a qualified provider before changing your diet.
Activity factors and weight-goal calorie shifts
| Setting | Value | Effect |
|---|---|---|
| Sedentary | 1.2 | Little or no exercise |
| Lightly active | 1.375 | Exercise 1-3 days/week |
| Moderately active | 1.55 | Exercise 3-5 days/week |
| Very active | 1.725 | Exercise 6-7 days/week |
| Extra active | 1.9 | Hard exercise or physical job |
| Lose 0.5 kg (1 lb)/week | −500 kcal/day | Common, sustainable deficit |
| Lose 1 kg (2 lb)/week | −1,000 kcal/day | Aggressive, watch the floor |
Multiply BMR by your activity factor for TDEE, then shift for your goal. Floors: ~1,200 kcal (women), ~1,500 kcal (men).
Frequently asked questions
How many calories should I eat to lose weight?
A daily deficit of 500 kcal below your TDEE is a common starting point for losing about 0.5 kg (1 lb) per week. For faster loss, a 1,000 kcal deficit targets about 1 kg (2 lb) per week, but most guidelines caution against going below 1,200 kcal per day for women or 1,500 kcal for men without medical supervision, as very low intakes risk nutrient deficiencies and muscle loss. This calculator flags any target that crosses those limits.
Which BMR formula should I choose?
Mifflin-St Jeor is the default and is considered the most accurate for most non-obese adults. The Revised Harris-Benedict equation is an older alternative that tends to read slightly higher. Katch-McArdle uses your lean body mass instead of total weight, so it is the best choice if you know your body fat percentage and have an athletic or very lean build, where weight-based formulas can overestimate your needs.
What is a zigzag or calorie-cycling plan?
A zigzag plan varies your daily calories across the week, some days higher and some lower, while keeping the seven-day average equal to your target. Many people find the higher days easier to stick to socially, and cycling may slightly reduce the metabolic adaptation that comes from eating the same low number every day. The calculator generates a sample 7-day schedule built around your goal calories.
What is TDEE and why does it matter?
TDEE stands for Total Daily Energy Expenditure, the total calories your body uses in a day, including resting metabolism and all physical activity. Eating at TDEE maintains your weight, below it creates a deficit for loss, and above it a surplus for gain. It is the foundational number for any evidence-based nutrition plan, which is why this calculator builds every weight goal, macro split, and time-to-goal estimate from it.