Calorie calculator
See how many calories a day hold your weight, what to eat to reach a goal weight, and when the scale stops moving. Including why.
Your calories
If you do not know it, we estimate it. That estimate only looks at your BMI, so it reads muscular people as far fatter than they are.
Enter your age, height and weight. It recalculates as you type, and nothing is sent anywhere.
This tool runs a validated model, but it predicts an average response and individual variation is large. It is not medical advice and not a diet prescription. Talk to a doctor or dietitian before cutting your intake substantially, particularly if you take medication, are pregnant, or have a history of disordered eating.
What does this tool work out?
First your maintenance: the intake that holds your weight where it is. Then the question you actually have. If you want a goal weight, it solves for the intake that gets you there by your target date. If you want to know what a given intake does, it draws the curve. Either way you see where it flattens, and how far your expenditure falls along the way.
Why is this number different from other calculators?
Most calculators take your expenditure, subtract 500 kcal, and divide the deficit by 7,700 kcal per kilo. That is the 3500 kcal rule, and it is wrong: it holds the deficit constant while your real expenditure falls, so it predicts straight-line weight loss forever with no plateau. This tool runs the dynamic model of Hall and colleagues (Lancet, 2011), the same model underneath the NIH Body Weight Planner. It tracks fat and lean mass separately, lets expenditure fall as your body shrinks, and adds the extra slowdown of adaptive thermogenesis on top. That last term is precisely the plateau.
How do you calculate your calorie needs?
Your calorie needs are your resting metabolism (BMR) times an activity factor. You estimate that resting rate with a formula: Mifflin-St Jeor is regarded as the most accurate for healthy adults, with the revised Harris-Benedict as the well-known alternative. Multiply your BMR by how active you are and you have your total daily expenditure, or TDEE. This tool goes a step beyond that fixed number: it runs the dynamic Hall/NIH model, so you also see how your expenditure falls as you lose weight.
See how to work it out by hand
Average daily calorie needs
Guideline values for adults aged 18 to 59; above 60 they are a little lower. Treat them as an average, because the calculator above works out your number personally.
| Lightly active | Moderately active | |
|---|---|---|
| Men | 2,400–2,500 kcal/day | 2,700–2,900 kcal/day |
| Women | 1,900–2,000 kcal/day | 2,200–2,300 kcal/day |
Source: Voedingscentrum (Netherlands). Lightly active = mostly sitting with some movement; moderately active = at least half an hour of moderate exercise a day.
You are sticking to it and the scale will not move
In order of how often it is genuinely the cause.
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1
Your expenditure has fallen
That is not failure, that is the curve above. A smaller body burns less, and on top of that your expenditure drops further still. At some point your old deficit is no longer a deficit. The answer is rarely to eat less, but to reset the deficit or move more.
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2
You are eating more than you think
This is by far the best-documented reason people lose less than a calculator promises. Under-reporting intake is the rule rather than the exception, and it is not about lying: oils, sips, leftovers and weekends all count and are rarely counted. Weigh everything for a week and you will know.
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3
And only then: something in your blood
This is the rarest of the three, but it is not zero. If your intake demonstrably adds up and your weight has not moved in months, a handful of values can explain it. An underactive thyroid lowers your expenditure. Insulin resistance makes losing weight harder. Low testosterone costs muscle, and muscle is what carries your expenditure.
Values that could explain it
Not a checklist and not a must. Only worth it once you have ruled out the above.
Put this tool on your own site
Copy the code below. The calculator runs entirely in your visitor's browser: nothing is sent anywhere and nothing is stored.
Frequently asked questions
How accurate is this calculator?
More accurate than the usual rule of thumb, but it is still an average. The underlying model has been tested against controlled feeding studies and predicts the average response of a group well. For one individual the spread is wide: the same intake plays out differently in different people. Treat the answer as a direction and adjust to what the scale actually does over four to six weeks.
Why does this promise less weight loss than other calculators?
Because the others hold your expenditure constant, and that is not what happens. On a 500 kcal daily deficit the classic rule promises almost 24 kilos after a year. This model gives just over 13. The difference is not pessimism, it is physiology: your body gets lighter, therefore burns less, and slows down further on top of that. The straight line does not exist.
What is adaptive thermogenesis?
The extra fall in energy expenditure when you eat less, over and above what your smaller body already explains. In this model it builds up with a time constant of about two weeks and settles at roughly fourteen percent of the change in intake. In practice: after a few months of dieting you burn anywhere from a few dozen to well over a hundred kcal a day less than you would expect. That is the plateau, and it is normal.
Why does the tool ask for my body fat percentage?
Because your starting point decides how the weight you lose splits between fat and muscle. Without a measurement we estimate body fat from your height, weight and age, and that estimate effectively only looks at your BMI. For someone carrying a lot of muscle it is badly off: a muscular 100 kilo man at 1.80 metres is estimated at nearly 28 percent body fat when he may be at 12. If you have a measured value, use it.
Why does the tool sometimes refuse to give a number?
Because some answers should not exist. If you want to lose a lot in a short time, the required intake drops below the floor that guidelines set for eating without supervision. We will not print that number, because somebody might follow it. Instead you get the earliest date the goal is safely reachable. And if the goal is so low that even that floor will not get you there, we say so.
How many calories do you need per day?
For most adults, daily calorie needs fall between 1,700 and 2,900 kcal. Your exact number depends on your sex, age, weight, height and how active you are. As a guideline, the Dutch nutrition authority puts an average man at around 2,500 kcal a day and an average woman at around 2,000 kcal. Enter your details in the calculator above for your personal number.
What is the difference between your BMR and your calorie needs?
Your BMR, your resting metabolism, is what your body burns at complete rest: breathing, heart, organs. Your calorie needs are more: your BMR plus everything you move in a day. Multiply your BMR by an activity factor and you have your total daily expenditure, or TDEE. That last number is the intake that holds your weight steady.
How many calories does a woman or man need on average?
As a guideline, a lightly active adult man needs around 2,400 to 2,500 kcal a day and a woman around 1,900 to 2,000 kcal. Move more and it rises: moderately active lands around 2,700 to 2,900 kcal for men and 2,200 to 2,300 for women. Men sit higher on average because they carry more muscle. These are averages; your own need may differ.
If your intake adds up and nothing moves
Then blood is the logical next step, and only then. Thyroid, fasting insulin and testosterone between them explain most of the cases where a real calorie deficit still does nothing.