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Calorie Calculator (TDEE & Macros)

Estimate your daily calorie needs (BMR and TDEE) with the Mifflin-St Jeor equation, adjust for your goal, and get a protein, carb and fat macro split. Everything is calculated in your browser.

Inputs

Physical Activity Level (PAL) multiplier applied to BMR.

If > 0, Katch-McArdle BMR is also shown (more accurate for lean athletes).

Formula

  • BMR (male) = 10·W + 6.25·H − 5·A + 5
  • BMR (female) = 10·W + 6.25·H − 5·A − 161
  • TDEE = BMR × PAL
  • Target kcal = TDEE × (1 + goal%)
  • Protein g = kcal·P% / 4 · Carbs g = kcal·C% / 4 · Fat g = kcal·F% / 9
  • Katch-McArdle BMR = 370 + 21.6 × LBM, LBM = W × (1 − BF%)

Basal Metabolic Rate (BMR) is the energy your body burns at complete rest. The Mifflin-St Jeor equation (1990) is the most accurate general-population predictive equation and is the one recommended by the Academy of Nutrition and Dietetics. Multiplying BMR by a Physical Activity Level (PAL) factor gives Total Daily Energy Expenditure (TDEE) — roughly the calories needed to maintain current weight. A deficit or surplus is applied as a percentage of TDEE rather than a fixed number, so the adjustment scales with body size. Macronutrients are then split by calorie share and converted to grams using the Atwater factors: 4 kcal/g for protein and carbohydrate, 9 kcal/g for fat.

Step-by-step calculation

  1. Basal metabolic rate

    10(75) + 6.25(175) − 5(30) + 5

    1,699 kcal/day

  2. Total daily energy expenditure

    1,699 × 1.375

    2,336 kcal/day

  3. Goal adjustment

    2,336 × (1 + 0%)

    2,336 kcal/day

  4. Protein

    2,336 × 30% ÷ 4 kcal/g

    175 g

  5. Carbohydrate

    2,336 × 40% ÷ 4 kcal/g

    234 g

  6. Fat

    2,336 × 30% ÷ 9 kcal/g

    78 g

Worked example

  • Male, 30 y, 175 cm, 75 kg, lightly active, maintain:
  • BMR = 10(75) + 6.25(175) − 5(30) + 5 = 1,698.75 kcal/day
  • TDEE = 1,698.75 × 1.375 = 2,335.8 kcal/day
  • Balanced split → 175 g protein, 234 g carbs, 78 g fat

Assumptions

  • Predictive equations carry roughly ±10% error versus indirect calorimetry.
  • PAL multipliers include both exercise and non-exercise activity (NEAT).
  • Atwater factors 4/4/9 kcal per gram; alcohol (7 kcal/g) is not modelled.
  • Results assume adults; they are not valid for children, pregnancy or lactation.

Tips

  • Track weight as a 7-day rolling average and adjust intake by ±100–150 kcal if the trend stalls for 2–3 weeks.
  • Keep protein at 1.6–2.2 g per kg of bodyweight when in a deficit to protect lean mass.
  • Keep fat above ~0.6 g/kg for hormone health; the rest of the calories can flex to carbs.
  • Enter body fat % if you know it — Katch-McArdle is more accurate for very lean or very heavy people.

Warnings

  • This tool is for general information only and is not medical advice.
  • Intakes below ~1,200 kcal/day (women) or ~1,500 kcal/day (men) should only be used under clinical supervision.
  • Consult a doctor or registered dietitian before changing your diet if you have any medical condition.

Standards & references

  • Mifflin MD et al., Am J Clin Nutr 1990;51:241-7
  • Katch-McArdle / Cunningham lean-mass equation
  • FAO/WHO/UNU Human Energy Requirements (PAL factors)

Frequently asked questions

Is my health data sent anywhere?

No. The calorie calculator runs entirely in your browser with JavaScript. Your age, weight, height and body-fat figures are never uploaded, stored on a server or shared.

Which formula does this calorie calculator use?

Mifflin-St Jeor for BMR by default, multiplied by an activity (PAL) factor for TDEE. If you enter a body-fat percentage, the Katch-McArdle equation is shown alongside it.

How many calories should I eat to lose weight?

A 10–20% deficit below TDEE is the usual safe range, giving about 0.5–1% of bodyweight lost per week. Larger deficits increase muscle loss and are harder to sustain.

How accurate is a calorie calculator?

Predictive equations are typically within about 10% of measured energy expenditure. Use the result as a starting point and adjust based on 2–3 weeks of real weight-trend data.

What macro split should I choose?

A balanced 30/40/30 split suits most people. Endurance athletes benefit from more carbs, while low-carb or keto splits are a personal preference — total calories and protein matter most.

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