Calorie Calculator
Estimate daily calories and protein, fat and carbohydrate targets from BMR and activity, with the equation shown, a published minimum-intake floor applied, and browser-only privacy.
Results
How many calories should I eat a day?
That is the question most readers arrive with, and this calorie calculator answers it by calculating calories in three stated steps rather than quoting a population average. Enter your measurements, pick an activity band and a goal, and the page returns a daily calorie intake in kcal, the maintenance figure it came from, and the macronutrient grams that target divides into.
There is no single correct answer to how many calories you need. Two people of the same height, weight, age and sex can differ by roughly 10 per cent in resting rate alone. What a calorie intake calculator can do is give a defensible starting point and show its working, which is why the equation, the multiplier and the goal adjustment are printed beside the result instead of collapsed into one unexplained integer.
The same three steps run in either direction. Set a loss goal and the page works out a deficit; set a gain goal and it becomes a calorie calculator to gain weight, adding 250 or 500 kcal a day to maintenance. Calculating calorie expenditure rather than intake is the maintenance figure itself, which the TDEE calculator breaks down further into resting rate, the thermic effect of food, exercise and everyday movement.
This is a free online calorie calculator, built as a calculator for calories and macronutrients together rather than either alone. It runs in your browser, stores nothing between visits and sends nothing to a server.
How the calorie target is worked out
Three steps, in order. First a resting metabolic rate, which is the energy your body uses at complete rest. Then a multiplier for how active you are, which turns that into maintenance — the intake at which your weight holds steady. Then your goal, which adds calories to maintenance or takes them away.
The default equation is Mifflin-St Jeor. For men, resting rate is 9.99 × weight in kilograms, plus 6.25 × height in centimetres, minus 4.92 × age in years, plus 5. For women the final term is minus 161 instead. Choosing Katch-McArdle replaces all of that with 370 + 21.6 × lean body mass in kilograms, where lean mass is your weight minus the body fat percentage you enter.
Nothing is rounded until the end. Entering U.S. customary measurements converts them to kilograms and centimetres first, because both equations are published in metric, so the two unit systems return the same answer for the same person.
Activity multipliers
The multiplier is the largest single source of error in the result, which is why the page shows you the one it used rather than folding it into a total. If you are between two bands, the lower one is the safer starting point.
| Band | Multiplier | Describes |
|---|---|---|
| Sedentary | 1.2 | Little or no exercise; a desk job |
| Lightly active | 1.375 | Light exercise 1–3 days a week |
| Moderately active | 1.55 | Moderate exercise 3–5 days a week |
| Very active | 1.725 | Hard exercise 6–7 days a week |
| Extra active | 1.9 | Very hard exercise, training twice a day, or a physical job |
Goals and the minimum-intake floor
Each goal is a fixed daily change to maintenance:
| Goal | Effect |
|---|---|
| Maintain weight | No change to maintenance |
| Mild weight loss | 250 kcal a day below maintenance |
| Weight loss | 500 kcal a day below maintenance |
| Extreme weight loss | 1,000 kcal a day below maintenance |
| Mild weight gain | 250 kcal a day above maintenance |
| Weight gain | 500 kcal a day above maintenance |
A goal is never delivered below the published minimum daily intake: 1,500 kcal a day for men and 1,200 kcal a day for women. Harvard Health states intake should not fall below those figures except under the supervision of a health professional, and a calculator cannot supervise anyone. When your goal would fall below the minimum, the target is raised to it and the page tells you exactly how many calories were added back and that your goal will take longer than its name suggests.
The floor never pushes a target above maintenance. If your maintenance intake is already at or below the minimum, there is no deficit that can be applied safely, so the calculator shows maintenance and says that losing weight from there is something to plan with a doctor or a registered dietitian.
The weekly figure beside the target applies the traditional 7,700 kcal per kilogram of body mass to the difference between your target and your maintenance. It is calculated from the target you were actually given, so a goal whose deficit was withheld reports the slower rate you will really experience. It also assumes the difference keeps working indefinitely, which it does not: expenditure falls as weight falls, so loss slows and eventually plateaus.
How the target divides into macronutrients
Protein and carbohydrate carry 4 kcal per gram, fat carries 9, so a calorie target divides into grams once a split is chosen. The same run that produces a daily calorie figure also produces the protein, fat and carbohydrate grams that go with it. The split follows your goal unless you pick one yourself.
| Split | Ratio | Default for |
|---|---|---|
| Balanced | 20% protein · 30% fat · 50% carbohydrate | The default when maintaining |
| Higher protein | 30% protein · 25% fat · 45% carbohydrate | The default for a loss goal |
| Higher carbohydrate | 20% protein · 25% fat · 55% carbohydrate | The default for a gain goal |
Because the split follows the goal, a loss goal defaults to the higher-protein split and a gain goal to the higher-carbohydrate one. Either can be overridden. If you already have a calorie figure and only want it divided up, the macro calculator does that on its own, including custom percentages.
All three sit inside the Acceptable Macronutrient Distribution Ranges published for adults in the Dietary Reference Intakes — 10 to 35 per cent of energy from protein, 20 to 35 per cent from fat and 45 to 65 per cent from carbohydrate. The result table shows that range beside each figure, so you can see the split is within it rather than take our word for it.
What this calculator does not tell you
It is an educational estimate for healthy adults aged 18 to 80, not medical or dietary advice, and not a diagnosis. Predicted resting metabolic rate varies from measured rate by roughly 10 per cent either way in an individual, and two people with identical measurements can genuinely need different intakes. Treat the target as a starting point and adjust it against what happens to your weight over several weeks.
It is not suitable during pregnancy or breastfeeding, for children or adolescents, or for anyone managing a condition, an eating disorder or a medication that affects appetite, weight or metabolism. Ages outside 18 to 80 are refused rather than estimated, because the equations are established for adults and a number this tool is not entitled to produce is worse than no number at all.
It says nothing about food quality, micronutrients, fibre, hydration, alcohol, timing or how any of this fits a medical condition. A calorie target is one input into eating well, not a plan.
Sources
- NIH Bookshelf: estimating resting metabolic rate with the Mifflin-St Jeor equation
- Dietary Reference Intakes: acceptable macronutrient distribution ranges
- Harvard Health: minimum daily calorie intake
Sources reviewed 26 August 2026.
Frequently asked questions
How many calories should I eat a day?
It depends on your resting metabolic rate, how active you are and what you want your weight to do. The calculator estimates resting rate from your height, weight, age and sex, multiplies it by an activity band to reach maintenance, then applies your goal. It will not report a target below the published minimum of 1,500 calories a day for men or 1,200 for women.
What is the difference between BMR and TDEE?
BMR is what your body uses at complete rest, keeping your heart, brain, lungs and organs running. TDEE is that figure multiplied by an activity band to cover everything else you do in a day, from walking to the kitchen to training. The calorie target is TDEE with your goal added to or taken from it.
Why will the calculator not go below 1,200 or 1,500 calories?
Because Harvard Health states intake should not fall below 1,200 a day in women or 1,500 a day in men except under the supervision of a health professional, and a web page cannot supervise anyone. If your goal works out below that figure, the calculator raises the target to the minimum and tells you how much it added back. If your maintenance intake is already at or below the minimum, it shows maintenance instead and recommends seeing a clinician.
Which equation should I choose?
Mifflin-St Jeor unless you have a reliable body fat measurement. It needs only height, weight, age and sex, and it is the equation that comes closest to measured resting metabolic rate across the general population. Katch-McArdle reads lean body mass instead, which suits people who are unusually lean or unusually muscular, but it inherits every error in the body fat figure you enter.
How accurate is a calorie calculator?
Predicted resting metabolic rate typically sits within about 10 per cent of measured rate for an individual, and the activity multiplier is a coarse band rather than a measurement, so the target is a starting point rather than a prescription. Track what actually happens to your weight over three or four weeks and adjust from there; your own trend is better evidence than any equation.
Why does a 500 calorie deficit not give exactly 0.5 kg a week?
Because it does not. A 500 kcal daily deficit is 3,500 kcal a week, which is about 0.45 kg at the traditional 7,700 kcal per kilogram — the familiar "0.5 kg" label is the rounded metric version of 1 lb. The calculator reports the arithmetic rather than the label. The same approximation also assumes the deficit keeps working indefinitely, whereas expenditure falls as weight falls, so real loss slows.
Does this page give me my macros?
It reports macros as part of the calorie result: once it has a daily target it divides that target into protein, fat and carbohydrate grams, using the split your goal implies or one you pick. If you already know your calories and want only the split, the dedicated macro calculator handles that and accepts custom percentages.
What macros should I eat to lose weight?
When you set a loss goal this page defaults to the higher-protein split: 30 per cent protein, 25 per cent fat and 45 per cent carbohydrate. You can override it, and every option offered stays inside the published Acceptable Macronutrient Distribution Ranges. The deficit comes from the calorie target rather than from the split.
Is this a calorie counter app?
No, and it is not trying to be. A calorie counter app tracks what you eat day by day; this page calculates the target you would be tracking against. The two do different jobs, and counting calories tells you little until you have the target. Work the number out here, then track against it in whichever food diary or calorie counter you already use.
Can I use this during pregnancy or breastfeeding?
No. Energy needs in pregnancy and lactation are set differently and are not what these equations describe. They are also not suitable for children or adolescents, or for anyone managing a condition, an eating disorder or a medication affecting appetite, weight or metabolism. Those needs are set with a clinician or a registered dietitian.