Complete guide
Reviewed July 2026Your daily calorie need is the amount of energy your body burns in 24 hours — and it's the single most useful number for managing weight. Eat that amount and weight holds steady; eat less and you lose fat; eat more and you gain. Everything else in nutrition is detail on top of this energy balance.
This calculator builds your number in two steps: it estimates your Basal Metabolic Rate (BMR) — the energy you'd burn at complete rest — using the well-validated Mifflin-St Jeor equation, then multiplies by an activity factor to get your Total Daily Energy Expenditure (TDEE). It also gives calorie targets for losing or gaining weight and a balanced macronutrient split.
Enter your details above for your numbers. Below: the formulas, worked examples, a calorie-goal table, the macro breakdown, and the mistakes that stall most people's progress.
How daily calories are calculated
The calculation is a two-stage pipeline: measurements → BMR → TDEE → goal calories. Each stage refines a resting estimate into your real, activity-adjusted need.
Step 1 — BMR (Mifflin-St Jeor)
Men: BMR = 10·weight(kg) + 6.25·height(cm) − 5·age + 5 Women: BMR = 10·weight(kg) + 6.25·height(cm) − 5·age − 161
BMR is the energy to keep you alive at rest — breathing, circulation, cell repair — and it's 60–70% of most people's total burn. The Mifflin-St Jeor equation (1990) is the most accurate general-population predictor and is what registered dietitians use.
Step 2 — TDEE (activity multiplier)
TDEE = BMR × activity factor. This is your maintenance level — the calories that hold your weight steady. Most people overestimate their activity; when in doubt, pick the lower factor and adjust from real-world results after 2–3 weeks.
| Activity level | Description | Multiplier |
|---|---|---|
| Sedentary | Desk job, little exercise | × 1.2 |
| Lightly active | Light exercise 1–3 days/week | × 1.375 |
| Moderately active | Moderate exercise 3–5 days/week | × 1.55 |
| Very active | Hard exercise 6–7 days/week | × 1.725 |
| Extra active | Physical job + hard training | × 1.9 |
Worked example
- Woman, 32, 68 kg, 165 cm, moderately active.
- BMR = 10×68 + 6.25×165 − 5×32 − 161 = 680 + 1031.25 − 160 − 161 = 1,390 kcal.
- TDEE = 1,390 × 1.55 = 2,155 kcal (maintenance).
- To lose ~0.5 kg/week: subtract 500 kcal → ~1,655 kcal/day.
- To gain lean mass: add 300–500 kcal → ~2,455–2,655 kcal/day.
Calorie goals: the math of losing and gaining
One kilogram of body fat stores roughly 7,700 kcal. A daily deficit therefore predicts weekly fat loss: 500 kcal/day × 7 days = 3,500 kcal ≈ 0.45 kg/week. The reverse builds mass, though a portion of surplus always becomes fat.
| Goal | Adjustment | Daily calories | Expected weekly change |
|---|---|---|---|
| Aggressive loss | −750 kcal | ~1,405 | −0.68 kg |
| Standard loss | −500 kcal | ~1,655 | −0.45 kg |
| Mild loss | −250 kcal | ~1,905 | −0.23 kg |
| Maintain | 0 | 2,155 | 0 |
| Lean gain | +300 kcal | ~2,455 | +0.27 kg |
Macronutrient split
Calories decide weight; macros decide body composition and satiety. A balanced, evidence-based starting split: protein 25–30% (crucial for preserving muscle in a deficit — aim for 1.6–2.2 g per kg of body weight), fat 25–30% (hormones and vitamin absorption; don't go below 0.5 g/kg), and carbohydrates filling the rest (training fuel). Protein at 4 kcal/g, carbs 4 kcal/g, fat 9 kcal/g.
How to use this calculator
- Enter weight, height, age and sex accurately — errors here propagate through every later number.
- Choose your activity level honestly; pick the lower option if you're unsure.
- Select your goal (lose, maintain, gain) to get the adjusted daily target.
- Use the maintenance (TDEE) figure as your anchor, and the goal figure as your daily budget.
- Track intake for 2–3 weeks, weigh under consistent conditions, and adjust by ±100–200 kcal based on the actual trend — the calculator is a starting estimate, your scale is the feedback loop.
Common mistakes
- Overstating activity — the biggest source of a too-high estimate. 'I go to the gym' rarely means 'very active' if the other 22 hours are sedentary.
- Forgetting that TDEE falls as you lose weight — a lighter body burns less, so recalculate every 4–5 kg.
- Under-eating protein in a deficit, which sacrifices muscle and rebounds as fat.
- Not counting liquid calories, cooking oils and 'bites while cooking' — these routinely add 200–400 hidden kcal.
- Weighing daily and panicking over water fluctuations; track the weekly average instead.
Frequently asked questions
Glossary
- BMR
- Basal Metabolic Rate — energy burned at complete rest; 60–70% of total daily expenditure.
- TDEE
- Total Daily Energy Expenditure — BMR × activity factor; your maintenance calories.
- Calorie deficit
- Eating fewer calories than you burn, causing weight (mainly fat) loss.
- Mifflin-St Jeor
- The most accurate general-population BMR equation, used by this calculator.
- Macronutrients
- Protein, carbohydrate and fat — the calorie-containing nutrients.
- Maintenance calories
- The intake at which weight stays constant — equal to TDEE.
- Activity factor
- The multiplier (1.2–1.9) converting BMR to TDEE based on lifestyle.
- Energy balance
- The relationship between calories in and calories out that governs weight change.
Key takeaways
Daily calories = BMR (Mifflin-St Jeor) × activity factor, then adjusted for your goal. Maintenance holds weight; a moderate 300–500 kcal deficit loses ~0.3–0.5 kg/week while protein at 1.6–2.2 g/kg protects muscle. The estimate gets you started; 2–3 weeks of honest tracking and weekly weigh-ins turn it into your real number. Recalculate as your weight changes.
Enter your stats above to get your BMR, TDEE and goal calories — then track for three weeks and fine-tune by ±150 kcal from your actual weight trend.