How Many Calories per Day Do You Need?

An average woman needs about 2,000 kcal a day and an average man about 2,500, according to the NHS. How many calories per day you need depends on your age, height, weight and how much you move. Your number can sit a few hundred kcal on either side of those averages. Below I run the 2023 US energy equation on two example adults to show how far a personal figure drifts from the average.

How many calories do I need a day on average?

The NHS gives 2,000 kcal for women and 2,500 kcal for men. Its page was last reviewed on 17 April 2023.

US numbers come as ranges. The Dietary Guidelines for Americans 2020–2025 put adult women at 1,600–2,400 kcal a day and adult men at 2,000–3,000 kcal. The newer 2025–2030 edition, published in January 2026, has no calorie table, so these ranges come from the older one. The tables use a reference woman, 5 ft 4 in (126 lb), and a reference man, 5 ft 10 in (154 lb). They sort people into three activity levels:

• Sedentary: only the activity of independent living.
• Moderately active: walking about 1.5 to 3 miles a day at 3 to 4 mph, on top of daily living.
• Active: walking more than 3 miles a day at that pace.

Australian food labels give energy in kilojoules, or in kilojoules and kilocalories. The conversion is 1 kcal = 4.184 kJ per the FAO, so 2,000 kcal is 8,368 kJ and 2,500 kcal is 10,460 kJ.

Both sets of figures describe a reference adult, and you may not resemble one. Taller, heavier or younger than that adult means more energy, shorter or older means less. The 2,000 for women gets its own breakdown in how many calories should a woman eat.

How many calories do I need for my age, height and weight?

Use the equations in the 2023 report Dietary Reference Intakes for Energy from the US National Academies of Sciences, Engineering, and Medicine, or NASEM. The adult equations take your age in years, height in cm, weight in kg and one of four activity categories. They were fitted to doubly labeled water data. In that method people drink water tagged with two isotopes, and their real energy use is traced over 7 to 14 days. The report describes it as the nutrition community’s benchmark standard for measuring energy use in free-living people.

Take a woman who is 42, 168 cm (5 ft 6 in) and 68 kg (150 lb). Her arithmetic in the low active row:

575.77 − (7.01 × 42) + (6.60 × 168) + (12.14 × 68) = 575.77 − 294.42 + 1,108.80 + 825.52 = 2,216 kcal

I ran the sum for every category. I also ran it for a 30-year-old man who is 180 cm (5 ft 11 in) and 82 kg (181 lb).

Activity category	Woman, 42 y, 168 cm, 68 kg (kcal a day)	Man, 30 y, 180 cm, 82 kg (kcal a day)
Inactive	2,048	2,754
Low active	2,216	2,976
Active	2,354	3,158
Very active	2,595	3,534

The NHS figure of 2,000 kcal sits just under the lowest estimate for this woman. The man’s lowest estimate is 254 kcal above the NHS 2,500. Neither adult is an outlier: their BMIs are 24.1 and 25.3, and the equation simply uses their size. Read each column as a band. An error of the size I cover below turns her 2,216 kcal into roughly 1,970–2,462 kcal.

Age moves the number less than weight does. For the US ranges laid out band by band, see how many calories to eat a day by age. The equation takes off 7.01 kcal per year of age for women and 10.83 kcal for men, which is 70 and 108 kcal per decade. Each extra kg adds 11.71 to 12.56 kcal for women and 14.10 to 19.11 kcal for men, depending on the category. A 2021 Science study adds a wrinkle. Adjusted for fat-free mass, daily energy use stays stable from age 20 to 60 and declines after that.

Put your own age, height and weight into the row you think fits, and round the result to the nearest 10 kcal.

Which activity category am I?

Pick the one that matches a normal week. Not your best one. The inactive category isn’t “lies on the sofa”. NASEM says people in it are not completely sedentary, only minimally active beyond daily living, and with little or no physical work.

The report’s Table 7-1 gives each category a typical day. Daily living for everyone is about 30 minutes of walking plus about 90 minutes of light to moderate tasks like vacuuming. Then:

Category	Typical day on top of daily living	Typical PAL
Inactive	nothing extra	about 1.4
Low active	60–80 minutes of walking at 3–4 mph	about 1.6
Active	30–50 minutes of walking, 45 minutes of moderate cycling and 40 minutes of doubles tennis	about 1.75
Very active	45 minutes of moderate cycling, about 25 minutes of jogging and 60 minutes of doubles tennis	about 2.05

PAL is the physical activity level, your total daily energy use divided by your basal energy use. A higher PAL means a bigger multiple of the energy you’d burn lying still.

The choice is worth real calories. For the woman above, each step up adds 168, 138 and then 241 kcal. For the man it adds 222, 182 and 376 kcal. NASEM says no reliable tool exists to sort one person into a category, so Table 7-1 is guidance, not a test. When two categories fit, I pick the lower one. That is my habit, not NASEM’s advice. A target that is a bit low shows up as weight loss you can correct. One that is a bit high shows up as a slow gain you may miss for months.

How many calories should I eat a day to lose weight, keep my weight or gain?

To keep your weight, eat your estimate. To lose, eat less than it, and to gain, eat more. The size of the gap decides the pace.

For losing, the 2013 AHA/ACC/TOS guideline describes a deficit of 500 or 750 kcal a day. Its usual targets run from 1,200 to 1,500 kcal for women and 1,500 to 1,800 kcal for men. I treat the lower ends as floors: don’t plan below 1,200 kcal if you’re a woman or 1,500 kcal if you’re a man. The NHS advises a pace of 1 to 2 lb, or 0.5 to 1 kg, a week. Take the man at low active. A 500 kcal gap puts him at 2,476 kcal a day.

On gaining, the NHS’s advice for people who need to add weight says adults could try 300 to 500 extra calories a day. The woman at low active, starting from 2,216 kcal, would aim at 2,516 to 2,716 kcal.

These are starting points. This page can’t tell you whether losing weight is right for you. Ask your doctor.

Your own number from your age, height, weight and activity is one step away in the calorie calculator. It uses the NASEM 2023 equations and never goes below 1,200 calories for women or 1,500 for men.

What does 2,000 calories look like in a day?

It looks like a lot of ordinary food, and a few small items carry a big share of it. I built one day from USDA FoodData Central records. Each portion is weighed in the state its record describes, and the energy is the record’s figure scaled to the grams. Where a record gives two energy values, I used the specific Atwater factors.

Meal	Food and grams	Energy (kcal)
Breakfast	Rolled oats, dry, 60 g	227
Breakfast	Greek yogurt, plain, whole milk, 150 g	142
Breakfast	Banana, 115 g	101
Breakfast	Almonds, raw, 20 g	117
Lunch	Chicken breast, braised, 150 g	249
Lunch	White rice, cooked, 158 g (1 cup)	205
Lunch	Broccoli, raw, 150 g	48
Snack	Apple, raw, 161 g (1 medium)	77
Snack	Peanut butter, creamy, 32 g	189
Dinner	Farmed salmon, cooked, 178 g (half a fillet)	367
Dinner	Red potatoes, raw, 250 g	183
Dinner	Olive oil, 13.5 g (1 tablespoon)	119
Total		2,024

Three items stand out. The olive oil, the peanut butter and the almonds weigh 65.5 g together and add up to 425 kcal, which is 21% of the day. To move the total by 200 kcal without changing the meals, I’d start with those three, and a kitchen scale shows what you actually use. How much of a day like this belongs at breakfast is its own question, covered in how many calories should breakfast be.

How do I check that my number is right?

Eat near it for two weeks, weigh yourself, and read the trend. That’s the whole test. The equation’s root-mean-square error is 246 kcal a day for women and 339 kcal for men, per the same NASEM tables. So the woman’s 2,216 kcal is a central guess, and her true figure could sit a few hundred kcal either side. More on estimating this number sits under calorie calculators.

Food records are noisy too. NASEM cites a yearlong study of 29 people in which getting within 10% of a person’s true average intake took an average of 31 days of records, so two weeks of logging won’t tell you your exact intake but it will show whether your weight is moving.

I check it this way, and no guideline backs the cutoffs. Weigh yourself on 3 mornings a week and average each week. I’d call anything under about 0.5 kg (1 lb) between weekly averages flat. Say week one averages 68.4 kg and week two 68.1 kg while you eat close to your estimate and log honestly. That 0.3 kg drop is flat by this standard, so the estimate is close to your maintenance. If it keeps rising, lower the target by 100 to 200 kcal and test again. A fall you didn’t plan means raising it.

If the scale moves while you eat your estimate, convert the drift into kcal. A common rule says one pound of body weight is 3,500 kcal, which is about 7,700 kcal per kg. Hall and colleagues showed it overstates loss over months. The body adapts. Over a few weeks I treat it as a workable approximation, and I use it only for that. A steady gain of 0.25 kg a week means about 275 kcal a day above maintenance (0.25 × 7,700 ÷ 7). A steady loss of the same size means 275 kcal below it.

Your usual exercise is already inside the category you picked. Adding the calories from a workout on top counts it twice.

The equations cover healthy adults. Pregnancy and breastfeeding add energy costs of their own, and your midwife or doctor sets those. Under 18, the figures differ, and this page isn’t written for you. If you have a health condition, or take a medicine that changes your appetite or weight, ask your doctor before you set a calorie target.

In Calsa, a short quiz sets your calorie goal, and it refuses to save one below the safe floor and says why. Whatever tool you use, the first number is a guess until two weeks of your own weigh-ins confirm it.