🍎 Calorie Calculator: Daily Calorie Needs and Macros
By Shihab Mia · Reviewed by ToolNimba Review Team, nutrition and health content review · Updated 2026-06-27
This calculator gives an estimate, not medical or dietary advice. Your real needs depend on body composition, health conditions, medications and lifestyle. Talk to a doctor or registered dietitian before changing your diet, especially if you are pregnant, under 18, an athlete, or managing a health condition.
Your daily calorie needs are the number of calories your body uses in a day to stay alive, move around and recover. This calculator estimates that figure with the Mifflin-St Jeor equation, the method clinicians and dietitians rely on, then adjusts it for your goal so you get a clear daily target. It also breaks your target into protein, carbohydrate and fat so you know not just how much to eat, but roughly what to eat.
What is the Calorie Calculator?
Every calorie target starts with your Basal Metabolic Rate (BMR), the energy your body burns at complete rest just to keep your heart, brain, lungs and other organs running. This tool calculates BMR with the Mifflin-St Jeor equation, which research has shown to be more accurate for most people than the older Harris-Benedict formula. For men the equation is 10 times weight in kg plus 6.25 times height in cm minus 5 times age plus 5; for women the final number is minus 161 instead of plus 5.
BMR alone is not your daily need, because almost nobody lies motionless all day. To get your Total Daily Energy Expenditure (TDEE), or maintenance calories, we multiply BMR by an activity factor that reflects how much you move: 1.2 for sedentary, 1.375 for light activity, 1.55 for moderate, 1.725 for active and 1.9 for very active. Eat at your TDEE and your weight stays stable.
From maintenance we apply your goal. To lose weight you eat below maintenance, to gain you eat above it. A 500 calorie daily change targets roughly one pound (about 0.45 kg) of body weight per week, and 250 calories targets about half that. This calculator offers mild and standard loss and gain options, and if your loss target would drop below a safe floor, about 1,200 calories for women and 1,500 for men, it raises the number back to the floor and warns you, because eating less than that without supervision makes it hard to get enough protein, vitamins and minerals.
Finally, the tool splits your goal calories into macronutrients using a balanced 30 percent protein, 40 percent carbohydrate and 30 percent fat ratio. Protein and carbohydrate each supply about 4 calories per gram and fat about 9, so the calculator converts each slice of calories into grams. This split is a sensible starting point; athletes, low-carb dieters and people with specific medical needs may want a different ratio, which a dietitian can help you set.
When to use it
- Working out a realistic daily calorie target before starting a weight loss or muscle gain plan.
- Finding your maintenance calories so you know the baseline your diet is built around.
- Turning a calorie goal into grams of protein, carbs and fat for meal planning or tracking apps.
- Comparing how different activity levels or goals change the number of calories you should eat each day.
How to use the Calorie Calculator
- Choose your sex and enter your age, then your height and weight using whichever units you prefer.
- Pick the activity level that best matches a typical week, being honest rather than optimistic.
- Select your goal, from losing weight through maintaining to gaining weight.
- Read your daily calorie target, your BMR and maintenance figures, and the suggested protein, carb and fat grams below.
Formula & method
Worked examples
Woman, 30 years, 165 cm, 68 kg, moderate activity, maintain weight.
- BMR = 10 x 68 + 6.25 x 165 - 5 x 30 - 161 = 680 + 1031.25 - 150 - 161 = 1400.25 kcal
- TDEE = 1400.25 x 1.55 = 2170 kcal (rounded)
- Goal = maintain, so goal calories = TDEE = about 2170 kcal
- Macros: protein 0.30 x 2170 / 4 = 163 g, carbs 0.40 x 2170 / 4 = 217 g, fat 0.30 x 2170 / 9 = 72 g
Result: About 2,170 kcal/day to maintain, with roughly 163 g protein, 217 g carbs and 72 g fat
Man, 40 years, 180 cm, 85 kg, light activity, lose weight.
- BMR = 10 x 85 + 6.25 x 180 - 5 x 40 + 5 = 850 + 1125 - 200 + 5 = 1780 kcal
- TDEE = 1780 x 1.375 = 2448 kcal (rounded)
- Goal = lose weight, adjustment -500, so goal calories = 2448 - 500 = 1948 kcal
- This is above the 1,500 kcal floor for men, so no clamp is needed
Result: About 1,950 kcal/day to lose roughly 1 lb (0.45 kg) per week
Activity factors used to turn BMR into daily calories (TDEE)
| Activity level | Factor | Who it fits |
|---|---|---|
| Sedentary | 1.2 | Desk job, little or no exercise |
| Light | 1.375 | Light exercise 1 to 3 days a week |
| Moderate | 1.55 | Moderate exercise 3 to 5 days a week |
| Active | 1.725 | Hard exercise 6 to 7 days a week |
| Very active | 1.9 | Very hard exercise or a physical job |
How each goal changes your daily calories
| Goal | Daily change | Approx weekly result |
|---|---|---|
| Lose weight | -500 kcal | About 1 lb (0.45 kg) lost |
| Mild loss | -250 kcal | About 0.5 lb (0.23 kg) lost |
| Maintain | 0 kcal | Weight stays steady |
| Mild gain | +250 kcal | About 0.5 lb (0.23 kg) gained |
| Gain weight | +500 kcal | About 1 lb (0.45 kg) gained |
Common mistakes to avoid
- Overstating your activity level. A few gym sessions a week is usually light to moderate, not active. Picking too high a factor inflates your calorie target, which quietly stalls weight loss. When in doubt, choose the lower level and adjust based on the scale.
- Treating the number as exact. The formula estimates an average for your stats; your true needs can be 200 or more calories either side. Use the result as a starting point, track your weight for two to three weeks, and tweak intake based on what actually happens.
- Eating below the safe calorie floor. Dropping under about 1,200 kcal for women or 1,500 for men makes it very hard to get enough protein, vitamins and minerals. If your loss target lands there, lose weight more slowly or get professional guidance.
- Ignoring protein when cutting calories. When you eat in a deficit, enough protein helps protect muscle. Hitting roughly the protein grams shown here, spread across the day, makes a lower-calorie diet easier to sustain and keeps more of your weight loss as fat.
Glossary
- Calorie
- A unit of food energy. On nutrition labels a Calorie is really a kilocalorie (kcal), the energy to heat one kilogram of water by one degree Celsius.
- BMR
- Basal Metabolic Rate: the calories your body burns at complete rest to keep its basic functions running.
- TDEE
- Total Daily Energy Expenditure, or maintenance calories: all the energy you burn in a day including rest, digestion, daily movement and exercise.
- Mifflin-St Jeor equation
- A widely used and accurate formula for estimating BMR from weight, height, age and sex.
- Calorie deficit
- Eating fewer calories than you burn, so the body draws on stored energy and you lose weight over time.
- Macronutrients
- Protein, carbohydrate and fat, the three nutrients that supply calories. Protein and carbs give about 4 calories per gram, fat about 9.
Frequently asked questions
How many calories should I eat a day?
It depends on your sex, age, height, weight, activity and goal. For a typical 30-year-old woman of average height and weight doing moderate exercise, maintenance is around 2,000 to 2,200 calories; for a similar man it is often 2,400 to 2,800. Enter your own details above for a personalised number.
Is the Mifflin-St Jeor equation accurate?
It is one of the most accurate prediction equations for everyday use and is the method many dietitians prefer over the older Harris-Benedict formula. Any equation is still an estimate, so treat the result as a strong starting point and adjust based on how your weight changes.
How many calories should I eat to lose weight?
Eat below your maintenance calories. A 500 calorie daily deficit targets about one pound (0.45 kg) of loss per week, and 250 calories targets about half that. Pick a loss goal above and the calculator subtracts the deficit for you, while keeping you above the safe calorie floor.
What are the safe minimum calories per day?
As a general guide, women should not drop below about 1,200 calories a day and men below about 1,500, because it becomes hard to meet nutrient needs. Very low calorie diets below these levels should only be followed under medical supervision.
What macros should I eat at my calorie target?
This tool suggests a balanced split of 30 percent protein, 40 percent carbohydrate and 30 percent fat, then converts it to grams. It is a sensible default for most people, but athletes, low-carb dieters and those with medical needs may benefit from a different ratio set with a dietitian.
Does this calorie calculator store my data?
No. Everything is calculated in your browser. Nothing you enter is sent to a server or saved anywhere, so your figures stay private to you.
Sources
- A new predictive equation for resting energy expenditure in healthy individuals , American Journal of Clinical Nutrition (Mifflin et al.)
- Counting calories: Get back to weight loss basics , Mayo Clinic