How many calories should I eat a day?

For most adults the answer falls between 1,600 and 3,000 calories, depending on size, sex, age and activity. Enter your details above for a figure specific to you rather than relying on the 2,000-calorie population average.

Is 1,500 calories a day enough?

For many smaller or sedentary women it is a reasonable weight-loss intake. For most men it is below the recommended floor of 1,500 and too aggressive to sustain. Compare it with your calculated maintenance rather than judging it in isolation.

Does calorie intake change with age?

Yes. Requirements fall gradually from around 30, mostly because muscle mass declines rather than because metabolism slows dramatically. Resistance training is the most effective way to slow that drift.

Should I eat back the calories I burn exercising?

If you selected an activity level that already includes your training, no - it is counted. If you chose sedentary and train separately, adding back roughly half of the estimated burn is a sensible compromise, since fitness trackers tend to overestimate.

How accurate is a calorie intake calculator?

Within about 10% for most people. Use the number for two to three weeks, track your weight trend, and adjust by 100-200 calories based on what actually happens.

Calorie Intake Calculator

Find how many calories a day you should eat for your body, your activity level and your goal.

Enter your details and your result will appear here.

What Is Calorie Intake?

This calorie intake calculator answers the question most people actually have: how many calories should I be eating a day?

It estimates the energy your body uses over a full day, then adjusts for what you want that intake to do - hold your weight steady, create a deficit, or support a gain.

Understanding Your Calorie Intake Result

Your daily requirement is built from two parts. The first is your basal metabolic rate, the energy needed just to keep you alive at rest, which typically accounts for 60-70% of the total. The second is everything on top: digestion, movement, work and exercise, captured by an activity multiplier.

Multiply the two and you have your total daily energy expenditure - the intake at which your weight stays flat. National guidelines quote around 2,000 calories a day for women and 2,500 for men, but those are population averages across every body size and activity level. A 5 ft 2 in sedentary woman and a 6 ft 2 in active man can differ by more than 1,500 calories a day, which is why a personal figure is worth more than a headline one.

How Is Calorie Intake Calculated?

Daily intake = BMR x activity factor, adjusted for your goal

BMR (Mifflin-St Jeor):
Men: 10w + 6.25h - 5a + 5
Women: 10w + 6.25h - 5a - 161

How to use this calculator

Enter your sex, age, height, weight and activity level. You will get your BMR, your maintenance intake, and targets for losing or gaining weight at different rates.

Choose your activity level based on a typical week rather than your best one. Sedentary means desk work with little deliberate exercise; moderately active means three to five training sessions a week.

What changes your daily calorie needs

Body size is the dominant factor - more tissue costs more energy to maintain, and lean tissue costs more than fat. Activity is next, and it varies more between people than any other component, largely through unconscious movement.

Age lowers requirements gradually. Illness, cold weather, pregnancy and heavy training raise them. Aggressive dieting lowers them somewhat beyond what the weight change alone predicts.

Turning the number into a plan

Use your maintenance figure as the baseline and set the deficit or surplus from there. For fat loss, 300-500 below; for lean gain, 250-400 above. Both are slow enough to be sustainable and fast enough to notice.

Once you have a target, check it against reality: two to three weeks of weight data will tell you whether the estimate fitted your body or needs nudging.

Methodology

BMR uses the Mifflin-St Jeor equation, validated as the most accurate general-population predictor in a well-known Academy of Nutrition and Dietetics review. Activity multipliers run from 1.2 (sedentary) to 1.9 (very heavy training or physical work). Goal adjustments are applied as fixed daily calorie offsets.

Worked Example

A 40-year-old woman, 5 ft 4 in and 150 lb, sedentary, has a BMR of about 1,320 calories and a maintenance intake near 1,580.

A 40-year-old man, 5 ft 11 in and 180 lb, moderately active, has a BMR of about 1,750 and a maintenance intake near 2,710. Both are entirely normal figures - the gap comes from size, sex and movement, not from one metabolism being better than the other.

Important Limitations

Prediction equations sit within roughly 10% of measured expenditure for most people, so treat the output as a starting estimate to test against the scale. Activity level is self-reported and consistently overestimated. Medical conditions, thyroid function and some medications shift requirements beyond what any formula captures. Not appropriate for children, or during pregnancy and breastfeeding, where requirements rise substantially.

Frequently Asked Questions

How many calories should I eat a day?: For most adults the answer falls between 1,600 and 3,000 calories, depending on size, sex, age and activity. Enter your details above for a figure specific to you rather than relying on the 2,000-calorie population average.
Is 1,500 calories a day enough?: For many smaller or sedentary women it is a reasonable weight-loss intake. For most men it is below the recommended floor of 1,500 and too aggressive to sustain. Compare it with your calculated maintenance rather than judging it in isolation.
Does calorie intake change with age?: Yes. Requirements fall gradually from around 30, mostly because muscle mass declines rather than because metabolism slows dramatically. Resistance training is the most effective way to slow that drift.
Should I eat back the calories I burn exercising?: If you selected an activity level that already includes your training, no - it is counted. If you chose sedentary and train separately, adding back roughly half of the estimated burn is a sensible compromise, since fitness trackers tend to overestimate.
How accurate is a calorie intake calculator?: Within about 10% for most people. Use the number for two to three weeks, track your weight trend, and adjust by 100-200 calories based on what actually happens.