Calorie Calculator: How Many Calories Should You Eat a Day?
Enter a few details and this calorie calculator estimates your daily calorie target for losing, maintaining, or gaining weight — with your maintenance calories shown right alongside.
What this calorie calculator does
This free online calorie calculator turns your body details and activity into a single daily number: how many calories to eat to reach your goal. It works as a quick calorie estimator for three intents — losing fat, holding your weight steady, or gaining — and shows your maintenance calories so you always have a clear point of reference.
Everything runs in your browser from the values you type. There is no signup, no tracking of your inputs, and no guesswork: the same equations used by dietitians power the result instantly.
How your daily calories are calculated
The calculation happens in two steps. First it estimates your Basal Metabolic Rate (BMR) — the energy your body uses at complete rest — with the Mifflin-St Jeor equation, the most accurate of the common BMR formulas for the general population:
Women: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161
Next it multiplies BMR by an activity factor (1.2 for sedentary up to 1.9 for very active) to get your Total Daily Energy Expenditure (TDEE), which is the same thing as your maintenance calories. Finally it applies your chosen rate: a deficit for fat loss or a surplus for weight gain.
Example: a 30-year-old man, 175 cm and 80 kg, moderately active, has a BMR of about 1,749 kcal and a TDEE of roughly 2,711 kcal. With a 500 kcal deficit his daily target is about 2,210 kcal to lose around half a kilogram per week.
Maintenance calorie calculator
Set the goal to Maintain and this tool becomes a maintenance calorie calculator: it returns the calories needed to keep your weight exactly where it is. If you have ever searched for a calculator for maintenance calories or a calorie maintain calculator, this is the number you were after — your TDEE, with no deficit or surplus applied.
To calculate calories for maintenance, you only need your maintenance figure; everything else is built from it. That is why this calories calculator maintenance view always displays your TDEE even when you pick a loss or gain goal — knowing your maintenance line makes it obvious how big a change you are really making.
Calorie deficit and surplus explained
A calorie deficit means eating fewer calories than you burn, which is the only reliable driver of fat loss. The simple calorie deficit formula is maintenance calories − daily deficit = intake, and roughly 7,700 kcal equals one kilogram of body fat (about 3,500 kcal per pound). So a 500 kcal daily deficit predicts close to 0.5 kg of loss per week.
This page shows the deficit (or surplus) so you can see exactly how far below or above maintenance you are eating. To go further and determine calorie deficit timelines — how many weeks to reach a target weight — divide the weight you want to lose by the weekly rate your deficit predicts: at 500 kcal a day that is about 0.5 kg per week, so 5 kg takes roughly ten weeks. A dedicated calorie deficit calculator is on the way, and that deficit calories calculator will turn the same numbers into an estimated date for hitting your goal.
Activity levels explained
| Level | Multiplier | Typical week |
|---|---|---|
| Sedentary | 1.20 | Desk job, little or no exercise |
| Lightly active | 1.375 | Light exercise 1–3 days |
| Moderately active | 1.55 | Moderate exercise 3–5 days |
| Active | 1.725 | Hard exercise 6–7 days |
| Very active | 1.90 | Hard daily training or a physical job |
If your week falls between two rows, pick the lower one — most people overestimate how active they are, and a slightly conservative target is easier to stick to.
Choosing calories for weight loss or gain
For fat loss, a moderate deficit of 250–500 kcal keeps energy and training quality high while the scale still moves. Larger deficits work faster but are harder to maintain and risk muscle loss, so reserve the 750–1,000 kcal options for short pushes. For weight gain, a small surplus of 250–500 kcal favours lean mass over excess fat. Whatever your goal, recalculate every few weeks as your weight changes.
Frequently Asked Questions
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It depends on your size, sex, age, and how active you are. However the question gets worded — “How many calories should I eat in day?”, “How many calories should I consume a day?”, “How many calories do I need to eat a day?” — the method behind it is the same: estimate maintenance (TDEE), then adjust for your goal. The calculator above does both in one step.
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To lose weight, subtract a deficit from maintenance. Asking “How many calories can I eat per day?” while losing fat usually comes down to maintenance minus about 500 kcal, which targets roughly half a kilogram (one pound) of loss per week. Smaller 250 kcal deficits suit those with little to lose; larger ones speed things up but are harder to hold.
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Your maintenance calories equal your TDEE. Set the goal to Maintain and the calculator shows the figure that keeps your weight stable — eat consistently around that number and your body weight should stay steady over time.
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“Calories” on food labels almost always mean kilocalories (kcal), so the figures here answer that directly. “How many kilocalories should I eat a day?” is the same question as your daily calorie target — read it straight from the result above.
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They mean the same thing. “How many calories should I have per day?” and “How many calories should I intake per day?” both ask for the total energy you take in from food and drink across the whole day. Aim for your calculated target as a daily average rather than an exact figure every single day.
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These estimates are typically within about 5–10% for most people, but individual metabolism varies. Treat the number as a starting point: track your weight for two to three weeks and nudge calories up or down if the trend isn't matching your goal.