Calorie needs calculator
Updated on 18 September 2026
Your daily calorie needs (TDEE) equal your basal metabolic rate — estimated with the Mifflin-St Jeor equation — multiplied by an activity factor. From this maintenance total, a deficit loses fat and a surplus builds muscle.
Knowing how many calories your body burns each day is the starting point of any physical transformation: you cannot lose fat or build muscle cleanly without this reference. This tool estimates your total energy expenditure, then derives the targets suited to your goal.
Fill in your age, height and weight to estimate your needs.
How the estimate is calculated
The tool uses the Mifflin-St Jeor equation, one of the most reliable for estimating basal metabolic rate — the energy your body burns at complete rest. It then multiplies this by an activity factor reflecting your lifestyle and training volume.
The result is your total daily energy expenditure (TDEE): the calorie count that keeps your weight stable. From there, a deficit loses fat, a surplus builds muscle.
Using your targets wisely
The proposed values are estimates: your real metabolism can vary. Treat them as a starting point, then adjust. If your weight does not move as expected after two weeks, raise or lower your calories by 100 to 200.
Aim for a moderate pace: about 0.5% of your body weight lost per week when cutting, a little less gained when bulking. Too aggressive, and you sacrifice muscle on a cut or accumulate fat on a bulk.
Splitting your calories into macros
Knowing your calorie total is only the first step: how you split it into protein, carbs and fat drives the quality of the result. At equal calories, enough protein makes the difference between losing fat and losing muscle.
Once you have your target calories here, run them through the macro calculator to turn them into grams of each nutrient. Both tools start from the same equation (Mifflin-St Jeor), so the numbers stay consistent.
The adaptive metabolism trap
After several weeks in a deficit, your metabolism slows slightly to save energy: this is metabolic adaptation. This slowdown explains why a cut sometimes stalls even though you are still eating the same thing.
This is not inevitable: a few days at maintenance calories every 6 to 8 weeks of dieting help limit this adaptation and preserve your metabolism over time. Recompute your targets then with your current weight.
Liquid calories and underestimated foods
Sugary drinks, alcohol, sauces and cooking oils are the main forgotten calorie sources in tracking. One extra glass of wine or spoon of oil quickly adds up to 100 to 150 uncounted kcal, several times a day.
If your results do not match the estimate despite seemingly rigorous tracking, these small sources often explain the gap. Log them for a few days to spot the invisible calorie leaks.
Endurance sport and high calorie needs
Endurance athletes (running, cycling, triathlon) often have calorie needs well above what a generic activity factor estimates, because long sessions burn far more energy than a typical strength session. Manually add the calories from very long sessions (over 1.5 hours) if the standard activity factor underestimates your output.
Conversely, a physically demanding job (construction, food service) combined with regular training can push the activity factor well beyond "very active". In that case, start from the highest factor offered and adjust based on your real results over two to three weeks.
Calorie cycling and refeed days
Rather than a fixed daily deficit, some trainees alternate lower-calorie days with one or two maintenance-calorie days (the "refeed"), especially during long cuts. This helps psychologically and may limit some effects of metabolic adaptation.
The weekly total is still what matters for weight loss: cycling your calories changes nothing to the balance if the 7-day total is the same. It is above all a comfort and adherence tool, not a miracle metabolic trick.
Frequently asked questions
Why does my estimate differ from other calculators?expand_more
Formulas and especially activity factors vary between tools. The activity factor is the main source of difference: be honest about your real level, since overestimating activity is the most common mistake.
Should I recalculate after losing weight?expand_more
Yes. Your needs decrease as your weight drops. Recalculate every 4 to 5 kilos lost to keep accurate targets and avoid stalling.
What is basal metabolic rate?expand_more
It is the energy your body spends at complete rest for its vital functions — breathing, circulation, brain. It makes up the largest share of your daily expenditure, before any physical activity.
Is exercise already counted in the activity factor?expand_more
Yes: the activity factor covers both your lifestyle and your training volume. So there is no need to add the calories burned in sessions separately, or you would count them twice.
Why have I stopped losing while in a deficit?expand_more
Often because your needs dropped with your weight, or portions drifted without notice. Recompute your targets, tighten tracking for a week or two, then adjust by 100 to 200 kcal if needed.
Do I need to count calories forever?expand_more
No. Counting is a temporary learning tool: after a few weeks, you recognize portions and calorie values of common foods without weighing. Many experienced trainees only count occasionally, to recalibrate their eye.
Is TDEE the same every day?expand_more
No, it varies slightly with your actual activity that day, your sleep and even digestion. The figure calculated here is a useful weekly average: aim for it across the week rather than perfect precision every single day.
Can I use this tool during an advanced cut?expand_more
Yes, but stay careful: at an already low body fat percentage, the calculation's margin of error matters more. Watch your energy and performance, and do not push through a deficit if fatigue becomes excessive.
What if I have a slow metabolism?expand_more
A genuinely slower-than-average metabolism exists, but it is rarer than people think: most cases come from underestimating what is eaten. Track your intake rigorously for two weeks before concluding you have a slow metabolism.
Are online calculators reliable?expand_more
They give a good starting estimate, with a 10 to 15% margin of error depending on the individual. Treat the figure as a starting point to adjust with your real results over 2 to 3 weeks, not as a fixed truth.
Are the calories burned shown by my watch reliable?expand_more
Rarely precise: smartwatches often overestimate expenditure by 20 to 30%, especially for strength training where the algorithm relies mostly on heart rate. Use them as a relative trend from session to session, not as an absolute figure to add up.
Should I eat the same calories on rest days?expand_more
It is not required, but it is simpler to follow. Some slightly reduce calories on non-training days, mainly through carbs, since the energy demand from exercise is absent that day.
Do alcohol calories really count?expand_more
Yes, fully: 1 g of alcohol provides 7 kcal, almost as much as fat, with no useful nutrient. Beyond the calories, alcohol also slightly reduces fat oxidation while it is being metabolized, which slows down an ongoing cut.
How long before I see a result after a calorie change?expand_more
Allow at least 10 to 14 days before judging: weight fluctuates day to day because of water, salt and digestion. Look at the trend over a multi-day average rather than a single weigh-in before adjusting again.
Sources
- menu_bookMifflin-St Jeor equation
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