How many calories should I eat a day?

Your maintenance calories (TDEE) are what you burn in a day, so eating that many keeps your weight steady. To lose weight, eat around 300 to 600 kcal less than that. The NHS uses roughly 2,500 kcal for men and 2,000 kcal for women as a general guide, but your own number depends on your size, age and activity.

What is the difference between BMR and TDEE?

BMR (basal metabolic rate) is the energy your body uses at complete rest just to stay alive. TDEE (total daily energy expenditure) adds everything else: walking, exercise, work and digesting food. TDEE is the number to base your diet on, not BMR.

How accurate is a calorie calculator?

The Mifflin-St Jeor equation used here estimates resting energy to within about 10% for most adults. Treat the result as a starting point, track your intake and weight for two to three weeks, then adjust by 100 to 200 kcal if your weight is not moving the way you expect.

Should I eat back the calories I burn exercising?

Not if you used the activity level in this calculator, because your exercise is already included in your maintenance calories. If you chose "Mostly sitting" and log workouts separately, eat back around half of the calories your watch reports, as fitness trackers tend to overestimate.

What is the lowest number of calories I should eat?

Unless you are under medical supervision, most guidance suggests not going below about 1,200 kcal a day for women or 1,500 kcal a day for men. Very low intakes make it hard to get enough protein, vitamins and minerals, and are harder to stick to.

Calorie calculator

Find your maintenance calories, a daily target to lose or gain weight, and the protein, carbs and fat to go with it. Works in kilograms or stone.

By the Calori team · Updated 21 October 2026 · 2 min read

Age

yrs

Weight

Height

Activity

Goal

Daily target

1,520kcal

Lose 0.5 kg a week

Maintenance (TDEE)

2,070kcal

Calories to keep your weight the same

BMR

1,510kcal

Burned at complete rest

Protein

135g

Carbs

140g

Fat

45g

How this calorie calculator works

The calculator works out your numbers in three steps, the same way a dietitian would on paper.

Basal metabolic rate (BMR). The energy you would burn lying still all day, calculated with the Mifflin-St Jeor equation from your sex, age, height and weight.
Total daily energy expenditure (TDEE). Your BMR multiplied by an activity factor, from 1.2 if you mostly sit to 1.9 if you have a physical job and train hard. This is your maintenance calories: eat this much and your weight should stay roughly the same.
Your daily target. Your TDEE with a deficit or surplus applied. A kilogram of body fat holds roughly 7,700 kcal, so eating about 550 kcal a day under maintenance works out at around 0.5 kg (just over a pound) a week.

The Mifflin-St Jeor equation

For adults, Mifflin-St Jeor is the most widely used way to estimate resting energy needs:

Men: (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5
Women: (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161

A 35-year-old woman who is 165 cm and 70 kg has a BMR of about 1,395 kcal. If she is lightly active, her maintenance calories are around 1,920 kcal, and a target of about 1,370 kcal would see her lose roughly half a kilo a week.

Choosing your activity level

Most people overestimate how active they are, which is the most common reason a calorie target does not work. If you have a desk job and go to the gym three times a week, “Lightly active” is usually more accurate than “Moderately active”. Steps help: under 5,000 a day is mostly sitting, 7,500 to 10,000 is lightly to moderately active, and 12,000 or more with regular training is very active.

How the macros are worked out

Once you have a calorie target, the calculator splits it into the three macronutrients:

Protein at 1.8 g per kg of body weight when losing weight (to help keep muscle) and 1.6 g per kg otherwise. Protein has 4 kcal per gram. See our protein calculator for more detail.
Fat at 28% of your calories, within the range most guidelines recommend. Fat has 9 kcal per gram.
Carbohydrate makes up the rest, at 4 kcal per gram.

These are sensible defaults, not rules. If you prefer more carbs and less fat, or the other way round, swap them gram for gram as long as protein and total calories stay about the same. Our guide on how to count macros explains how.

Using your number

A calorie target is only useful if you know roughly what you are eating. Track everything for two to three weeks, weigh yourself a few times a week at the same time of day, and compare the weekly average rather than single days. If the average is not moving after three weeks, drop your target by 100 to 200 kcal; if you are losing faster than 1% of your body weight a week, add some back.

Most people stop tracking because logging meals takes time. Calori makes it quicker: take a photo of your plate and the AI calorie counter estimates the calories and macros for you, then shows how much of your daily target is left.

A note on safety. These numbers are estimates for healthy adults. If you are pregnant, breastfeeding, under 18, have a medical condition or a history of disordered eating, speak to your GP before changing how you eat.

For more on losing weight, read our guide to calorie deficits, or try a ready-made 1500, 1800 or 2000 calorie meal plan.

Frequently asked questions

How many calories should I eat a day?: Your maintenance calories (TDEE) are what you burn in a day, so eating that many keeps your weight steady. To lose weight, eat around 300 to 600 kcal less than that. The NHS uses roughly 2,500 kcal for men and 2,000 kcal for women as a general guide, but your own number depends on your size, age and activity.
What is the difference between BMR and TDEE?: BMR (basal metabolic rate) is the energy your body uses at complete rest just to stay alive. TDEE (total daily energy expenditure) adds everything else: walking, exercise, work and digesting food. TDEE is the number to base your diet on, not BMR.
How accurate is a calorie calculator?: The Mifflin-St Jeor equation used here estimates resting energy to within about 10% for most adults. Treat the result as a starting point, track your intake and weight for two to three weeks, then adjust by 100 to 200 kcal if your weight is not moving the way you expect.
Should I eat back the calories I burn exercising?: Not if you used the activity level in this calculator, because your exercise is already included in your maintenance calories. If you chose "Mostly sitting" and log workouts separately, eat back around half of the calories your watch reports, as fitness trackers tend to overestimate.
What is the lowest number of calories I should eat?: Unless you are under medical supervision, most guidance suggests not going below about 1,200 kcal a day for women or 1,500 kcal a day for men. Very low intakes make it hard to get enough protein, vitamins and minerals, and are harder to stick to.