How many calories should you eat a day?

The short answer

Most adults need roughly 1,800–2,600 calories a day to maintain weight, but the right number depends on your size, body composition, age and activity. For fat loss, a deficit of about 300–500 calories a day is a sustainable starting point — and an accurate tracker is what turns that estimate into a target you can actually hit.

A calorie is simply a unit of energy. The “calories” on a food label are really kilocalories — the energy your body can extract from that food and use to power everything from breathing to running. The number you should eat each day is the amount that matches your goal: the same as you burn to maintain weight, fewer to lose it, more to gain.

What determines how many calories you need

Your daily requirement is the sum of four things: your basal metabolic rate (the energy to keep you alive at rest, which is the largest share), the thermic effect of food (energy spent digesting what you eat), non-exercise activity (fidgeting, walking, standing) and deliberate exercise. Together these make up your total daily energy expenditure, or TDEE.

Bigger bodies and people with more muscle burn more at rest. Requirements fall gradually with age, and they swing day to day with how much you move. That is why a single fixed number is only ever an estimate.

How to estimate your daily calorie target

A reasonable starting point for maintenance is to estimate your TDEE from your weight, height, age, sex and activity level using a standard equation, then adjust based on what actually happens on the scale over two to three weeks. If your weight is stable, that intake is your maintenance. From there:

To lose fat: subtract about 300–500 calories a day.
To maintain: eat at your estimated TDEE.
To gain muscle: add roughly 200–350 calories a day alongside resistance training and enough protein.

Why the “calories in” side is harder than it looks

The catch is that both sides of the equation are estimates. Food labels carry a legal tolerance, restaurant portions vary, and eyeballing a serving is notoriously unreliable. This is where measurement matters: read our explainer on how accurate calorie counting really is for the full picture. The practical takeaway is that a more accurate log makes your target meaningful, while a sloppy one quietly defeats it.

How nutrition apps set and track your calorie target

A good tracking app does three useful things: it estimates your maintenance, applies a sensible deficit or surplus for your goal, and then makes hitting that target low-effort enough that you keep doing it. The leaders go further by adjusting your target as you go — factoring in the calories you burn from workouts and wearables so your daily budget reflects what you actually did.

In our testing, Welling AI does this most cleanly. It sets a personalised calorie and macro target, logs meals in seconds by photo, chat or voice, and automatically adjusts the budget around your activity — so the number you are aiming for stays honest day to day. For most people, that combination of an accurate target and effortless logging is what turns “how many calories should I eat” from a one-off calculation into a habit that produces results. See our best calorie tracker for weight loss ranking for the full comparison.

References and further reading

Hall KD, et al. Energy balance and its components: implications for body weight regulation. American Journal of Clinical Nutrition, 2012.
United States Department of Agriculture & HHS. Dietary Guidelines for Americans, 2020–2025. Estimated calorie needs by age, sex and activity.
The Nutrition Wire. How accurate is calorie counting?

Frequently asked questions

How many calories should I eat to lose weight?

Most people lose weight steadily on a deficit of about 300–500 calories below their maintenance level, which tends to produce roughly 0.25–0.5 kg of fat loss per week. Larger deficits work faster but are harder to sustain and risk muscle loss. Calculate your maintenance first, then subtract.

Is 1,200 calories a day too low?

For most adults, yes. Very-low-calorie diets around 1,200 calories are difficult to sustain, often leave you short on protein and micronutrients, and can stall progress through poor adherence. A smaller, more liveable deficit usually wins over time.

Do I need to count calories to lose weight?

Not strictly, but self-monitoring your intake is one of the strongest predictors of weight-loss success in the research. A tracker that makes logging fast and accurate — by photo or chat rather than tedious search — makes the habit far easier to keep.