Estimate your daily calorie needs using the Mifflin-St Jeor equation. See your BMR, maintenance calories (TDEE), a target for your goal, and a suggested macronutrient split.
For informational purposes only. These estimates are not a substitute for professional guidance. Consult a healthcare professional or registered dietitian before making significant changes to your diet or activity, especially if you have a medical condition, are pregnant, or are under 18.
Your Basal Metabolic Rate, or BMR, is the number of calories your body burns at complete rest to keep essential functions running, such as breathing, circulating blood, regulating temperature, and repairing cells. It represents the minimum energy you need if you did nothing but lie still all day. BMR is influenced by your weight, height, age, and sex, and it typically accounts for the largest share of the calories you burn each day.
Total Daily Energy Expenditure, or TDEE, is the full picture. It takes your BMR and multiplies it by an activity factor to account for movement, exercise, and the energy cost of digesting food. TDEE is what most people mean by "maintenance calories": eat around this number and your weight tends to stay stable. Eat consistently below it and you create a deficit that leads to weight loss; eat above it and you create a surplus that supports weight or muscle gain.
This calculator uses the Mifflin-St Jeor equation, which research has found to be one of the more accurate predictive equations for resting energy expenditure in the general population. It uses weight in kilograms, height in centimeters, and age in years:
Men: BMR = 10 x kg + 6.25 x cm - 5 x age + 5 Women: BMR = 10 x kg + 6.25 x cm - 5 x age - 161
To convert BMR into TDEE, multiply by an activity factor: 1.2 for sedentary, 1.375 for light activity, 1.55 for moderate activity, 1.725 for active, and 1.9 for very active lifestyles. For weight goals, a common rule of thumb is that a deficit or surplus of about 500 calories per day corresponds to roughly one pound of change per week, since a pound of body fat stores about 3,500 calories. This tool applies a -500 target for losing and +500 for gaining, while enforcing a safe minimum intake floor.
Picking the right activity multiplier matters, because it can shift your TDEE by hundreds of calories. Sedentary describes someone with a desk job and little intentional exercise. Light activity fits people who work out one to three days a week or walk regularly. Moderate suits three to five structured workouts a week. Active describes near-daily training, and very active is reserved for people who train hard most days or have physically demanding jobs such as construction. When in doubt, choose the lower option; it is easier to add calories later than to unknowingly eat in a surplus. Many people also find it helpful to track their weight over two or three weeks and adjust their estimate based on real results rather than relying on the formula alone.
Consider a 30-year-old man who weighs 70 kg, stands 175 cm tall, and exercises moderately. His BMR is 10 x 70 + 6.25 x 175 - 5 x 30 + 5, which is 700 + 1,093.75 - 150 + 5, or about 1,649 calories per day. Multiplying by the moderate activity factor of 1.55 gives a TDEE of roughly 2,555 calories, which is his estimated maintenance level.
If his goal is to lose weight, subtracting 500 gives a target of about 2,055 calories per day. Using a 30/40/30 split, that works out to roughly 154 grams of protein, 206 grams of carbohydrate, and 68 grams of fat daily. Protein and carbohydrates each provide 4 calories per gram while fat provides 9, which is why the fat figure in grams is smaller even though it makes up the same share of calories.
The macro split shown here is a reasonable general starting point, not a prescription. Protein supports muscle repair and helps you feel full, and needs are often higher for people who are very active or trying to preserve muscle while losing fat. Carbohydrates are the body's primary energy source and fuel higher-intensity exercise. Fat is essential for hormone production and the absorption of certain vitamins. Individual needs vary with training, health conditions, and personal preference, so use these numbers as a framework and adjust based on how you feel and perform. A registered dietitian can tailor targets to your specific situation.