Calorie calculator
Estimate daily calories and macronutrients from body data and activity.
Fill in the fields and the result will appear here automatically.
This tool estimates resting energy expenditure using the simplified Mifflin–St Jeor equation, applies a selected activity multiplier and then your calorie adjustment. Protein and fat percentages determine the remaining carbohydrate energy. It compares assumptions; it does not establish an individual dietary requirement or predict weight change.
How it works
Formula and logic
Resting energy = 10w + 6.25h − 5a + 5 for the male equation, or −161 instead of +5 for the female equation. TDEE = resting energy × activity factor; the scenario target is TDEE × (1 ± p/100). Divide protein and carbohydrate calories by 4 and fat calories by 9 to obtain grams. REE means resting energy expenditure, estimated here with the equation.
Example
Male equation, 80 kg, 180 cm and age 30: 1780 kcal at rest × 1.55 = 2759 kcal. A 20% reduction gives 2207.2 → 2207 kcal. With 35% protein and 25% fat, rounded totals are 193 g protein, 61 g fat and 221 g carbohydrate.
Fields and units
- Gender — Male / Female
- Age — years
- Height — cm
- Weight — kg
- Activity level — list option
- Goal — Lose weight / Maintain / Gain weight
- Calorie adjustment for goal, % — unitless
- Protein share, % — unitless
- Fat share, % — unitless
How to use
- — Choose the formula sex and enter age 19–78, height in cm and weight in kg.
- — Select activity using your whole day, including work, travel and exercise.
- — For loss or gain, set an adjustment of 0–30%; maintenance ignores this field.
- — Set protein and fat at 10–60% each, with a combined total no greater than 100%.
Method and limitations
- Calculation method
- Formula and logic
- Data or methodology source
- Mifflin et al., 1990: resting energy equation, development cohort aged 19–78 NIDDK: adult nutrition-planning limitations, not validation of this static scenario
- Limitation
- Estimated resting expenditure and a conditional food-energy scenario, not an individual prescription. Activity multipliers and adjustment percentages are assumptions.
FAQ
How should I choose a calorie reduction?
The 0–30% field, initially 15%, compares scenarios. It does not guarantee safety or a particular weight-loss rate.
Are the default macro percentages optimal?
30/25/45 is a starting allocation of energy, not an individual prescription. A protein-plus-fat total above 100% is rejected instead of silently rescaled.
Why can actual weight change differ?
Energy intake and expenditure are estimates, and body weight also reflects water and other changes. This static calculation does not model adaptation or kilograms per week.
What do the activity multipliers represent?
They are adopted factors from 1.2 to 1.9. Workout counts alone do not establish daily expenditure; the original Mifflin study does not validate these five categories.
Who is outside this nutrition scenario?
The product age range 19–78 follows the development cohort. Pregnancy, breastfeeding, illness and prescribed diets require separate assessment that this tool does not provide.