Calorie calculator
How many calories do you burn per day?
Work out your total daily energy expenditure with the Mifflin-St Jeor equation — the same one the Myron coach starts with. For a target intake, pick your goal calculator:
Your daily calorie expenditure
And who's going to count that every day?
Myron tracks your calorie target for you — you speak, the AI logs. "Scrambled eggs from three eggs and two slices of whole-grain bread" is all it takes.
How this calculator works
It's built on the Mifflin-St Jeor equation, which estimates your basal metabolic rate from weight, height, age and sex — the most reliable of the common formulas in comparison studies. Your BMR is multiplied by your activity factor (PAL) to get your total daily energy expenditure. Depending on your goal, the calculator subtracts a moderate deficit or adds a surplus — converted at ~7,700 kcal per kilogram of body mass.
| Activity level | Factor |
|---|---|
| Sedentary, little training | 1.2 |
| Lightly active | 1.375 |
| Moderately active | 1.55 |
| Very active | 1.725 |
| Extremely active | 1.9 |
The macro recommendation follows sports science instead of rigid percentages: protein by body weight and goal (1.8–2.4 g/kg), fat as a baseline (0.9 g/kg), and the rest goes to carbs — your fuel for training.
Frequently asked questions
How does this calculator work out my calorie needs?
Your basal metabolic rate is calculated with the Mifflin-St Jeor equation from weight, height, age and sex — considered the most accurate standard formula today. Multiplied by your activity level (PAL factor) it gives your total daily energy expenditure; depending on your goal, a moderate deficit or surplus is applied on top.
What's the difference between BMR and TDEE?
Your basal metabolic rate (BMR) is the energy your body burns at complete rest. Your total daily energy expenditure (TDEE) adds everyday movement, work and training via the activity factor — it's the number your calorie target is anchored to.
How many calories should I eat to lose weight?
A moderate deficit of about 300–500 kcal below your TDEE (roughly 0.25–0.5 kg per week) is the best trade-off between progress, muscle retention and sustainability for most people. More aggressive deficits work short-term but raise the risk of muscle loss and rebound.
How much protein do I need?
For strength training and dieting, 1.8–2.4 g of protein per kg of body weight is well supported: more when cutting (muscle protection), a bit less when bulking. The calculator adjusts the recommendation to your goal automatically.
How accurate is a calculator like this?
Formulas estimate — real-world deviations of ±10 % are normal, because metabolism and daily movement are individual. The result is a good starting point; the truth shows in your weight trend over 2–3 weeks. That's why the Myron app continuously recalculates your true expenditure from your own history instead of stopping at the formula.
Formula: Mifflin MD, St Jeor ST et al. (1990): A new predictive equation for resting energy expenditure in healthy individuals — more under Methodology & data sources. More to look up: calorie tables · exercise directory.