The tool
The calculation returns a day's calorie needs and how they split into protein, carbs and fat, for losing weight, holding steady, or gaining. It applies Mifflin-St Jeor, the equation the literature keeps as the most accurate in adults, and switches to Katch-McArdle as soon as body fat is filled in.
No account, no sign-up, no cap. Measurements go in as pounds and feet or as kilos and centimeters, and they stay in the browser: nothing is sent, nothing is stored.
The calculation
Calorie needs come out in two steps: resting metabolic rate, what the body spends at complete rest, then a multiplier that accounts for the day. The first step is where calculators differ, and the one they name least often.
10 × weight in kg + 6.25 × height in cm − 5 × age, then + 5 for men and − 161 for women.
The 2005 systematic review published in the Journal of the American Dietetic Association places it ahead of the other equations in healthy adults, with or without excess weight. It is the formula applied here by default.
370 + 21.6 × lean mass in kg. It reads neither sex, nor height, nor age: only the non-fat tissue, which is the part that spends.
It gains accuracy where weight alone describes a frame badly, in both directions: the very lean profile as much as the heavy one. It asks for a measurement not everyone has, hence the optional field.
The 1919 equation, revised in 1984, is still the one behind most calculators. It was built on two hundred people, and its revision resets the coefficients without changing the population.
It overestimates expenditure in a documented way: around 70 kcal of resting rate for a man of 80 kg, 176 lb, which is close to 110 kcal of target once the activity level is applied.
The second step
Between the first level and the last, expenditure varies by 58 percent. No other answer in the form shifts the result that far, and it is also the only one that gets estimated rather than measured.
The marker is not training, it is the day. Someone standing eight hours a day spends more than a person who sits down and lifts weights three times a week. When in doubt, the level below is easier to correct than the level above.
| Level | The day | Multiplier |
|---|---|---|
| Sedentary | Sitting most of the day, little or no walking. | × 1.2 |
| Light | A bit of walking every day, or sport 1–3 times a week. | × 1.375 |
| Moderate | Standing part of the day, or sport 3–5 times a week. | × 1.55 |
| High | A physical job, or sport 6–7 times a week. | × 1.725 |
| Very high | A physically demanding job and daily training. | × 1.9 |
The split
It is set on body weight and not as a share of calories: 2.2 g per kg when losing, 2 g when gaining, 1.8 g when maintaining. A percentage would lower protein at the exact moment the deficit makes it most useful.
25 percent of calories when losing as much as when gaining, 30 when maintaining. The fat floor matters: going too low touches hormonal balance and the absorption of fat-soluble vitamins.
They take what is left of the target once protein and fat are set. It is the most flexible slot, and the one that adjusts without breaking anything else in the day.
Grams convert with the Atwater coefficients: 4 kcal per gram of protein and carbs, 9 for fat. The three add up to the target shown, give or take the rounding.
The lower bound
The floor is the higher of two numbers: the resting metabolic rate of the profile, and an absolute minimum of 1,200 kcal for women, 1,500 for men.
Without it, an ambitious pace on a small frame produces targets no automatic calculation has any reason to generate: a woman of 45 kg, 99 lb, at 152 cm, 5 ft, sedentary, was handed 942 kcal a day in the version that had no floor. When the floor lifts the target, the page says so, and states the pace that is actually left.
Two people of the same weight, height, age and sex do not spend the same amount, and the spread from one to the next commonly runs ten to twenty percent. A calculator gives a starting point, and nothing more, which is already what it is asked for.
Real expenditure gets measured, by reading logged intake against the weight trend over several weeks. That is what Zemiam does next, and it is why today's number opens the tracking rather than replacing it.
Questions
Mifflin-St Jeor for resting metabolic rate, the equation the Academy of Nutrition and Dietetics has kept since its 2005 systematic review as the most accurate in healthy adults, with or without excess weight.
When body fat is filled in, the calculation switches to Katch-McArdle, which reads lean mass only. The formula that was applied is named under the result, every time.
The Harris and Benedict equation dates from 1919, on two hundred people, and its 1984 revision resets the coefficients without changing the population. It overestimates expenditure in a documented way: around 70 kcal of resting rate for a man of 80 kg, close to 110 kcal of target once activity is applied.
Most calculators still use it. That is not a scandal, it is simply the formula that came before.
No, the field stays optional. Without it, Mifflin-St Jeor returns a perfectly usable result.
With it, Katch-McArdle gains accuracy on the builds that weight alone describes badly, in both directions: the very lean profile as much as the heavy one. A consumer body fat scale stays approximate, and an approximate value is worth more here than a missing one.
A calorie floor applies: the higher of resting metabolic rate and an absolute minimum, 1,200 kcal for women and 1,500 kcal for men. An ambitious pace on a small frame would otherwise produce a target below resting rate, which no automatic calculation has any reason to generate.
When the floor lifts the target, the page says so and states the pace that is actually left. A setting whose effect is cancelled without a word is worth less than a setting that is not there.
It is a starting point, not a measurement. A population equation describes an average, and the spread from one person to the next commonly runs ten to twenty percent: two people of the same weight, height, age and sex do not burn the same amount.
The only way to know real expenditure is to measure it, by reading logged intake against the weight trend over several weeks. That is what the app does next, and it is why the formula opens the tracking rather than replacing it.
No. It applies a published equation to typed measurements, nothing more. Pregnancy, breastfeeding, a chronic condition, an ongoing treatment or an eating disorder change needs that no formula of this kind describes.
In those situations the number to follow is a doctor's or a dietitian's, not a web page's.
Yes, with no account, no sign-up and no usage cap. Nothing is stored: what gets typed stays in the browser and goes nowhere.
This calculator applies published equations to typed measurements. It replaces neither a doctor nor a dietitian, and it does not suit pregnancy, breastfeeding, a chronic condition, or an eating disorder.
The day's number gets filled with servings whose composition is known. The Zemiam recipes each carry the calories and macros of their serving, recalculated from the same table as the rest of the site.
For what gets weighed one item at a time rather than as a dish, the food pages give calories and macros by real serving (an apple, an egg, a plate of pasta) rather than per hundred grams.
Next
Calorie needs say what a day asks for, never where a build sits. Body mass index answers that other question, with the full WHO classification, the waist circumference the index alone ignores, and the weight range that matches a normal build for a given height.
BMI calculatorIn Zemiam, a photo of the meal is enough to log the day, and the target then recalculates on measured expenditure rather than on the formula from day one.
