Understanding how many calories your body needs each day is the foundation of any informed nutrition or fitness plan. Our free Calorie Calculator estimates your daily calorie requirement based on your age, gender, height, weight, and activity level. The result is your Total Daily Energy Expenditure (TDEE) — the number of calories you need to maintain your current weight, along with adjusted targets for weight loss or gain.
Calories are units of energy. Every activity — from breathing and digestion to exercise and deep thinking — burns calories. When you consistently consume more calories than you burn, you gain weight; when you consume fewer, you lose weight. This calculator gives you a personalized daily baseline so you can make informed choices about your diet and lifestyle.
How Daily Calorie Needs Are Calculated
This calculator uses the Mifflin-St Jeor equation, the most widely validated formula for estimating Basal Metabolic Rate (BMR) — the number of calories your body burns at complete rest. It was developed from a study of 498 participants and is recommended by the American Dietetic Association as the most accurate general-use formula.
BMR (men) = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5
BMR (women) = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161
The BMR is then multiplied by an activity factor to produce TDEE. Activity factors: Sedentary (desk job, little exercise) × 1.2; Lightly active (1–3 days/week) × 1.375; Moderately active (3–5 days/week) × 1.55; Very active (6–7 days/week) × 1.725; Extra active (physical job + training) × 1.9.
Worked Examples
Example 1 — Sedentary adult male: Age 35, height 178 cm, weight 80 kg. BMR = 10×80 + 6.25×178 − 5×35 + 5 = 800 + 1,112.5 − 175 + 5 = 1,742.5. TDEE (sedentary × 1.2) = 2,091 calories/day.
Example 2 — Active adult female: Age 28, height 165 cm, weight 60 kg. BMR = 10×60 + 6.25×165 − 5×28 − 161 = 600 + 1,031.25 − 140 − 161 = 1,330.25. TDEE (moderately active × 1.55) = 2,062 calories/day.
Example 3 — Weight loss target: A person with a TDEE of 2,200 calories wants to lose 1 lb per week. A 500-calorie daily deficit (2,200 − 500 = 1,700 cal/day) produces roughly 1 lb of fat loss per week, since 1 lb of fat ≈ 3,500 calories.
Calorie Needs by Goal
| Goal | Daily Calories vs TDEE | Expected Weekly Change |
|---|---|---|
| Lose weight (slow) | TDEE − 250 cal | ~0.5 lb (0.23 kg) loss |
| Lose weight (standard) | TDEE − 500 cal | ~1 lb (0.45 kg) loss |
| Lose weight (fast) | TDEE − 750 cal | ~1.5 lb (0.68 kg) loss |
| Maintain weight | TDEE | No change |
| Gain muscle (slow) | TDEE + 250 cal | ~0.5 lb (0.23 kg) gain |
| Gain muscle (standard) | TDEE + 500 cal | ~1 lb (0.45 kg) gain |
Tips for Managing Calorie Intake
Calorie counting is most effective when combined with attention to food quality. 2,000 calories of whole foods (vegetables, lean protein, complex carbs, healthy fats) affects your body very differently from 2,000 calories of processed food — even if the calorie count is identical. A deficit that relies on cutting calories from nutrient-dense foods can leave you deficient in key vitamins and minerals, making it harder to sustain long-term.
Protein is particularly important in a calorie deficit. Consuming adequate protein (typically 0.7–1.0 g per pound of body weight) while in a deficit helps preserve muscle mass and increases satiety, making it easier to stick to your target. Muscle burns more calories at rest than fat, so preserving it supports long-term weight management.
Frequently Asked Questions
How many calories should I eat per day to lose weight?
A general guideline is to eat 500 fewer calories than your TDEE per day, which creates a deficit of 3,500 calories per week — roughly 1 lb of fat. However, the right deficit depends on your starting weight, activity level, and health status. Never go below 1,200 calories/day (women) or 1,500 calories/day (men) without medical supervision, as very low intakes can cause nutrient deficiencies and metabolic adaptation.
What is BMR and how is it different from TDEE?
BMR (Basal Metabolic Rate) is the number of calories your body burns at complete rest — the energy needed just to keep your organs functioning. TDEE (Total Daily Energy Expenditure) is BMR multiplied by an activity factor, representing your total daily calorie burn including exercise and daily movement. TDEE is the number you should use for diet planning.
Why do calorie calculators give different results?
Different calculators use different formulas. The Mifflin-St Jeor equation (used here) is considered the most accurate for most adults. Older formulas like Harris-Benedict tend to overestimate by 5–10%. No formula is perfectly accurate for every individual — use the result as a starting estimate and adjust based on real-world results over 2–4 weeks.
Does exercise significantly increase calorie needs?
Yes, but often less than people expect. A 30-minute moderate run burns roughly 250–350 calories for an average adult — equivalent to a small snack. The activity multipliers in this calculator capture the cumulative effect of your general lifestyle, which tends to have a bigger impact than individual workouts.
Are all calories equal for weight management?
For pure weight change, a calorie is a calorie — a deficit of 3,500 calories produces roughly 1 lb of fat loss regardless of source. However, different foods affect hunger, energy levels, and nutrient status differently. High-protein and high-fiber foods increase satiety, making it easier to maintain a deficit, while ultra-processed foods may drive overeating despite adequate calories.
How accurate is this calorie calculator?
This calculator uses the Mifflin-St Jeor equation, which research shows is accurate to within 10% for most people. Individual variation in metabolism, hormones, gut microbiome, and genetics means the result should be treated as a well-informed estimate, not a precise measurement. Track your weight over 2–3 weeks and adjust your intake if results differ from expectations.