How many calories should you eat per day?
Basal rate, total burn and your goal target — via Mifflin-St Jeor, the same formula our Nutrition Engine runs.
Estimate using the Mifflin-St Jeor method with a moderate activity level — the same calculation the Nutri Engine uses in your plan, refined with your real routine. It does not replace individual medical or nutritional advice.
| Goal | Adjustment on TDEE | Expected outcome |
|---|---|---|
| Lose fat | −20% (deficit) | 0.5–1% of body weight per week, keeping muscle with high protein |
| Maintain | 0% (maintenance) | Stable weight; the phase between cutting and gaining cycles |
| Build muscle | +10% (surplus) | 0.25–0.5% of body weight per month, minimizing fat gain |
The three numbers that define your diet
Every serious meal plan starts with three numbers. The first is basal metabolic rate (BMR): what your body burns at complete rest just to keep heart, brain, breathing and temperature running — typically 60–70% of everything you burn in a day.
The second is total daily energy expenditure (TDEE): BMR multiplied by your activity level, adding work, commuting, chores and training. It is what you actually burn on a normal day — and the reference number for every diet decision.
The third is your calorie target: TDEE adjusted for your goal. Eating your TDEE maintains weight; about 20% less creates the deficit that burns fat; about 10% more builds muscle with minimal fat. The calculator above returns all three at once.
Why we use Mifflin-St Jeor (not Harris-Benedict)
The Mifflin-St Jeor equation, published in 1990, is rated by the Academy of Nutrition and Dietetics as the most accurate BMR estimate for the general population — with roughly a 10% error margin, against larger deviations from the century-old Harris-Benedict, which tends to overestimate.
The formula: men = (10 × weight) + (6.25 × height in cm) − (5 × age) + 5; women = (10 × weight) + (6.25 × height in cm) − (5 × age) − 161. A 30-year-old man at 80 kg and 1.75 m has a BMR near 1,740 kcal — and with moderate activity, a total burn around 2,520 kcal.
No formula is perfect: genetics, muscle mass and hormones vary. The number is a starting point — fine-tuning comes from how the scale and the mirror respond over the first 2–3 weeks.
Using your target day to day
Target in hand, the priority order is: hit the weekly calorie total (the average matters more than a perfect day), secure daily protein, and split the rest between carbs and fat as you prefer. There is no time of day that makes you fat — only totals that run over.
- Weigh or photograph meals for the first 14 days — that’s where estimation errors live
- If weight hasn’t moved in 2 weeks, adjust the target by ±150 kcal
- Training and rest days can share the same target: simpler, and it works
- Free meals fit the plan if the weekly average absorbs them
The shortcut: logging without weighing anything
The main reason diets get abandoned is not hunger — it’s logging friction. In ShapeLeague you photograph your plate and the AI logs calories and macros by itself, closes your daily balance and adjusts the menu when you slip. The target this calculator gave you is the same one the app then tracks for you, meal by meal.
Reviewed July 2026
Frequently asked questions
How many calories to lose weight?
Generally 20% below your TDEE. If you burn 2,500 kcal, aim around 2,000 kcal — a deficit that burns fat without stalling metabolism or wrecking training.
How many calories to build muscle?
About 10% above your total burn, with protein between 1.6 and 2.2 g per kg. Bigger surpluses speed up fat gain more than muscle gain.
What are BMR and TDEE?
BMR is what you burn at complete rest (just to exist). TDEE is your full daily burn: BMR times an activity factor. Diets are always planned on TDEE.
What is the Mifflin-St Jeor method?
The BMR equation rated most accurate by the Academy of Nutrition and Dietetics, superseding the older Harris-Benedict. It uses weight, height, age and sex.
Do I need to eat the same calories every day?
No. The weekly average is what matters. Many people eat slightly less on weekdays to leave room for the weekend — it works just the same.
Is 1,200 calories a day safe?
For most adults it’s too aggressive: energy, training and adherence collapse, and muscle loss grows. Moderate deficits (300–500 kcal) lose nearly as fast at a fraction of the cost.
Does calorie counting actually work?
It’s the only mechanism any diet works through — low-carb, fasting or flexible, they all end in a calorie deficit. The difference is which one you can sustain.
Does my burn change as I lose weight?
Yes. A smaller body burns less. Recalculate every 4–6 kg lost — or use an app that recalibrates automatically, like ShapeLeague.
Now turn that number into a plan
The quiz uses these same formulas — plus your real routine — to build training and diet your way. Takes 60 seconds.
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