Use this tool to estimate maintenance calories and adjust for fat loss or muscle gain. It supports practical planning for nutrition and body-composition goals.
Your daily calorie need is determined by two factors: your Basal Metabolic Rate (BMR) — the energy your body burns at rest — and your physical activity level. The Mifflin-St Jeor equation, used by this calculator, is the most accurate method validated for the general population, with a margin of error of roughly ±10%.
For a 35-year-old woman, 5'5" (165 cm), 150 lbs (68 kg): BMR ≈ 1,441 calories/day. Multiplied by an activity factor of 1.55 (moderately active, exercise 3–5 days/week), her TDEE is approximately 2,233 calories/day. To lose 1 lb/week, she'd eat around 1,733 calories. To gain weight or build muscle, she'd eat 2,433–2,533 calories.
Activity multipliers explained: Sedentary (desk job, no exercise) = 1.2; Lightly active (light exercise 1–3 days/week) = 1.375; Moderately active (exercise 3–5 days/week) = 1.55; Very active (hard exercise 6–7 days/week) = 1.725; Extra active (physical job + hard exercise) = 1.9. Most people overestimate their activity level — when in doubt, choose one level lower than you think.
Calorie Goals for Weight Loss, Maintenance, and Gain
Weight loss: Aim for a deficit of 300–500 calories per day from your TDEE for sustainable loss of 0.5–1 lb/week. Larger deficits (750–1,000 cal/day) can accelerate loss to 1.5–2 lb/week but risk muscle loss and hunger. The minimum safe intake is generally 1,200 calories/day for women and 1,500/day for men.
Maintenance: Eat at TDEE. This is the right goal if you're happy with your current weight or are an athlete maintaining performance during a training block.
Muscle gain (bulking): A surplus of 200–350 calories above TDEE supports muscle growth with minimal fat gain for most people. Larger surpluses ("dirty bulking") build muscle faster but also add significant fat that must later be cut. Protein intake should be 0.7–1g per pound of bodyweight during a bulk.
Cutting (fat loss while preserving muscle): Use a modest deficit (300–400 cal) and high protein (1g/lb bodyweight). Resistance training is essential to signal muscle retention even in a calorie deficit.
Macronutrient Breakdown for Your Calorie Goal
Calories come from three macronutrients: protein (4 cal/gram), carbohydrates (4 cal/gram), and fat (9 cal/gram). A common starting split for most goals is 30% protein / 40% carbs / 30% fat, though this varies by goal:
Fat loss: Higher protein (35–40%) to preserve muscle, moderate carbs (30–35%), moderate fat (25–30%). Protein is also the most satiating macronutrient, helping you stay fuller on fewer calories.
Endurance sports: Higher carbohydrates (50–60%) fuel training and glycogen replenishment; protein 20–25%; fat 20–25%.
Strength training/bodybuilding: High protein (30–40%), moderate carbs (35–45%), lower fat (15–25%). Carbs support training intensity; protein supports muscle protein synthesis.
Use our Macro Calculator to break your calorie goal into specific gram targets for protein, carbs, and fat based on your goal.
Frequently Asked Questions
How many calories should I eat to lose weight?
Create a deficit of 300–500 calories per day below your TDEE for sustainable fat loss of 0.5–1 lb/week. Your TDEE is calculated above based on your stats and activity level. Never go below 1,200 calories (women) or 1,500 calories (men) without medical supervision — very low calorie diets cause muscle loss and metabolic slowdown.
Why am I not losing weight even in a calorie deficit?
The most common reasons are: (1) Inaccurate calorie tracking — studies show people underestimate intake by 20–50%. Weigh food with a kitchen scale instead of estimating portions. (2) Overestimated activity level — using "very active" when you're "lightly active" inflates your calculated TDEE. (3) Metabolic adaptation — prolonged deficits reduce BMR by 10–15%. Try a 2-week diet break at maintenance, then resume the deficit. (4) Water retention from high-sodium foods, stress, or hormonal changes can mask fat loss on the scale for weeks.
Do calories matter more than food quality?
For weight change, calories are the primary driver. However, food quality profoundly affects body composition, health, energy, and satiety. 1,800 calories of whole foods (lean protein, vegetables, whole grains) results in better body composition, better hormonal health, and less hunger than 1,800 calories of processed food — even at identical calorie counts. The best approach is both: hit your calorie target with mostly whole, minimally processed foods.
How do I track calories accurately?
Use a food scale (±1g accuracy) for at least the first few months. Apps like MyFitnessPal, Cronometer, or Lose It have extensive food databases. Key habits: weigh food raw/uncooked (cooking changes weight), log everything including cooking oils and condiments (highly calorie-dense), and scan barcodes rather than searching for food names (less error). After a few months, you'll develop accurate portion sense without needing to weigh everything.
