How many calories should I eat a day?
The number of calories you need each day depends on your age, sex, height, weight and how active you are. A small, inactive woman may need around 1,600–1,800 kcal to keep her weight steady, while a tall, very active man may need more than 3,000 kcal. That is why general advice such as “eat 2,000 calories a day” rarely fits anyone exactly. This free calorie calculator gives you a personal number for losing, maintaining or gaining weight in under a minute.
How the calorie calculator works
First, the calculator estimates your Basal Metabolic Rate (BMR) — the energy your body uses at complete rest — with the Mifflin-St Jeor equation, which research has found to be the most accurate everyday formula for adults:
- Men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5
- Women: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161
Next, it multiplies your BMR by an activity factor (from 1.2 for a desk job with no exercise to 1.9 for very hard daily training) to get your maintenance calories, also called TDEE. Finally it adds or subtracts calories for your goal. One kilogram of body fat stores roughly 7,700 kcal, so a daily deficit of about 550 kcal leads to around 0.5 kg of weight loss per week.
Example: a 35-year-old woman, 165 cm and 75 kg, lightly active: BMR = 750 + 1,031 − 175 − 161 = 1,445 kcal. Maintenance = 1,445 × 1.375 ≈ 1,987 kcal. To lose 0.5 kg a week she would eat about 1,437 kcal a day.
Daily calorie ranges: low, normal and high intakes
Typical maintenance needs for healthy adults are shown below. Your own result may be higher or lower.
| Daily intake | Women | Men | What it means |
|---|---|---|---|
| Low | Below 1,200 kcal | Below 1,500 kcal | Too low without medical supervision — risk of nutrient gaps, muscle loss and fatigue |
| Normal (maintenance) | 1,600 – 2,400 kcal | 2,000 – 3,000 kcal | Usual range depending on size and activity |
| High | Above 2,400 kcal | Above 3,000 kcal | Suitable only for very active, tall or athletic people; otherwise leads to weight gain |
Benefits of knowing your calorie needs
- Lose weight without crash dieting: a moderate deficit lets you lose fat steadily while still enjoying family meals.
- Stop guessing: you can see why a weight plateau happens and adjust your portions with confidence.
- Protect muscle and energy: eating enough — not too little — keeps your metabolism, mood and training on track.
- Plan balanced meals: once you know your calories, the macro calculator splits them into protein, carbs and fat.
- Healthy weight gain: if you are underweight, a calorie surplus helps you gain weight steadily rather than through junk food.
Health warnings
- Do not go below 1,200 kcal (women) or 1,500 kcal (men) a day unless a doctor or dietitian is supervising you.
- Calorie calculators are estimates and can be 10–20% off for an individual. Track your weight for a few weeks and adjust.
- If you have diabetes, kidney disease, thyroid problems, PCOS or take medication that affects appetite or blood sugar, get personal advice before cutting calories.
- Pregnant and breastfeeding women need extra calories and should not diet to lose weight.
- If counting calories makes you anxious or leads to skipping meals or bingeing, stop and speak to a professional.
Tips to hit your calorie target
Build meals around protein (eggs, chicken, fish, lentils, Greek yoghurt), high-fibre carbohydrates and plenty of vegetables — they fill you up for fewer calories. Watch liquid calories such as juices, sweetened coffee and soft drinks, and measure cooking oil and ghee, which add 120–130 kcal per tablespoon. Our guides to understanding calories and portion sizes have more ideas, and the weight loss calculator shows when you could reach your goal.
Frequently asked questions
How many calories should I eat to lose weight?
Eat about 300–550 kcal a day less than your maintenance calories. This usually leads to steady weight loss of 0.25–0.5 kg per week, which is easier to keep up and protects muscle.
Is 1,200 calories a day enough?
For most adults 1,200 kcal is the lowest safe intake without medical supervision, and it is too low for most men and active women. Very low intakes make it hard to get enough protein, iron, calcium and fibre.
Why am I not losing weight on my calorie target?
Common reasons are underestimating portions, cooking oils, drinks and weekend meals, water retention, or the calculator overestimating your activity. Track honestly for two weeks, then lower your intake by 100–200 kcal or add more daily steps.
Should I eat back the calories I burn exercising?
The activity level in this calculator already includes your exercise, so you do not need to add exercise calories on top. Choose the activity level that matches a normal week.
Which formula does this calorie calculator use?
It uses the Mifflin-St Jeor equation for resting metabolism, multiplied by a standard activity factor. Studies show Mifflin-St Jeor predicts resting energy needs within 10% for most healthy adults.
Do calorie needs change with age?
Yes. Metabolism slows slightly with age, mostly because we lose muscle. Recalculate every few months or after a weight change of 5 kg or more.
Sources
- Mifflin MD, St Jeor ST, et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr 1990;51:241–247.
- Frankenfield D, et al. Comparison of predictive equations for resting metabolic rate. J Am Diet Assoc 2005;105:775–789.
- U.S. Dietary Guidelines for Americans 2020–2025, estimated calorie needs.
- NHS. Understanding calories.