How many calories should I eat a day?

There is no single number. It depends on your size, age, sex, activity and goal, which is what this calculator estimates. Use the result as a starting point and adjust based on your weight trend.

Is a 500-calorie deficit safe?

For most healthy adults with weight to lose it is a common, moderate target. If it takes you below roughly 1,500 calories (men) or 1,200 (women), use a smaller deficit or add activity instead.

Do I need to eat back exercise calories?

If you selected an activity level that already includes your training, no. Adding exercise calories on top double-counts them.

Why am I not losing weight at my calculated target?

Usually because intake is higher than estimated, activity is lower, or water-weight changes are masking fat loss. Track for two to three weeks before changing the number.

Calorie Calculator

Work out how many calories a day you need to lose, maintain or gain weight.

Enter your details and your result will appear here.

What Is Calorie?

This calculator estimates the calories you need each day for the goal you choose. It works out your resting needs, scales them for how active you are, then applies a deliberate adjustment for weight loss, maintenance or gain.

Understanding Your Calorie Result

Daily calorie needs come from three things you can estimate and one you cannot control directly: body size, age and sex set your resting rate; activity scales it up; and individual variation of roughly 5-10% remains no matter how carefully you measure. A pound of body weight is conventionally treated as 3,500 calories, so a 500-calorie daily change corresponds to about 1 lb a week.

How Is Calorie Calculated?

Target calories = BMR x activity factor + goal adjustment

Methodology

BMR is calculated with Mifflin-St Jeor, multiplied by an activity factor between 1.2 and 1.9 to give maintenance calories, then adjusted by 250 or 500 calories a day depending on the goal you select.

Worked Example

A 40-year-old woman who is 5 ft 4 in and 155 lb, lightly active, has a BMR of about 1,376 calories and maintenance of about 1,892 calories. Choosing to lose 1 lb per week gives a target of roughly 1,392 calories a day.

Important Limitations

The 3,500-calorie rule overstates long-run loss because energy expenditure falls as body mass drops. Calorie labels carry their own error, and self-reported intake is commonly underestimated by 20% or more. Very low targets are flagged in the results and are not appropriate without professional supervision.

Frequently Asked Questions

How many calories should I eat a day?: There is no single number. It depends on your size, age, sex, activity and goal, which is what this calculator estimates. Use the result as a starting point and adjust based on your weight trend.
Is a 500-calorie deficit safe?: For most healthy adults with weight to lose it is a common, moderate target. If it takes you below roughly 1,500 calories (men) or 1,200 (women), use a smaller deficit or add activity instead.
Do I need to eat back exercise calories?: If you selected an activity level that already includes your training, no. Adding exercise calories on top double-counts them.
Why am I not losing weight at my calculated target?: Usually because intake is higher than estimated, activity is lower, or water-weight changes are masking fat loss. Track for two to three weeks before changing the number.