How Many Calories Should I Eat a Day? Find Your Number

Most adults need somewhere between about 1,800 and 3,000 kcal a day to keep their weight stable. As a rough guide, the NHS uses 2,000 kcal for an average woman and 2,500 kcal for an average man. Your own number depends on your sex, age, height, weight and how active you are, so the most useful answer is a personal estimate that you then check against your real weight trend.

This guide shows you how to work out how many calories you should eat a day, what the number means for weight loss, maintenance or gain, and why any calculator result is a starting point rather than a verdict.

The short answer: typical daily calorie needs

National nutrition bodies publish reference values for groups of people. The German Nutrition Society (DGE), for example, gives these guide values for adults of a healthy reference weight (BMI 22), at three levels of physical activity (PAL, explained below):

Age	Women, low activity (PAL 1.4)	Women, higher activity (PAL 1.8)	Men, low activity (PAL 1.4)	Men, higher activity (PAL 1.8)
19 to 24	1,900 kcal	2,500 kcal	2,400 kcal	3,100 kcal
25 to 50	1,800 kcal	2,400 kcal	2,300 kcal	3,000 kcal
51 to 64	1,700 kcal	2,200 kcal	2,200 kcal	2,800 kcal
65+	1,700 kcal	2,100 kcal	2,100 kcal	2,800 kcal

Three patterns stand out:

• Men usually need more than women, mainly because they tend to be larger and carry more muscle.
• Needs drift down with age. The drop is gradual: about 100 to 200 kcal from one adult age group to the next in these tables.
• Activity matters as much as age. The gap between a desk-bound and an active lifestyle is 600 to 700 kcal a day at the same age.

These are averages for groups. They are a sensible sanity check, but they cannot tell you what you need. For that, you need a personal estimate.

How to calculate how many calories you should eat a day

Your daily calorie need has two parts: the energy your body burns at rest, and everything you add on top by moving, working and digesting food. If you want a deeper look at the two, see our guide to BMR vs TDEE.

Step 1: Estimate your resting energy with Mifflin-St Jeor

The Mifflin-St Jeor equation was developed in 1990 from measurements in 498 healthy adults of normal weight and with obesity. A systematic review of the common equations found it was the most reliable of those tested: it predicted resting metabolic rate within 10% of the measured value in more people than any other equation.

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

Step 2: Multiply by an activity factor

To turn resting energy into a full day, multiply it by an activity factor. Many calculators, including the one in PixNutri, use these:

Activity level	Factor	What it looks like
Sedentary	1.2	Desk job, little planned exercise
Lightly active	1.375	Light exercise or plenty of walking 1 to 3 days a week
Moderately active	1.55	Moderate exercise 3 to 5 days a week
Very active	1.725	Hard exercise or a physical job most days

Researchers express the same idea as a physical activity level (PAL): total daily energy divided by resting energy. The FAO/WHO/UNU expert report classifies a sedentary or lightly active lifestyle as PAL 1.40 to 1.69, an active one as 1.70 to 1.99 and a vigorous one as 2.00 to 2.40. The calculator factors above are a practical, slightly more conservative version of the same scale.

Be honest here. It is easy to overestimate how active you are, and choosing one level too high can add 250 to 300 kcal a day to the estimate.

A worked example

Take a 35-year-old woman who is 165 cm tall, weighs 70 kg and is lightly active.

1. Resting energy: 10 × 70 + 6.25 × 165 − 5 × 35 − 161 = 700 + 1,031 − 175 − 161 = about 1,395 kcal
2. Daily need: 1,395 × 1.375 = about 1,920 kcal

Now a 40-year-old man, 180 cm, 85 kg, moderately active:

1. Resting energy: 850 + 1,125 − 200 + 5 = 1,780 kcal
2. Daily need: 1,780 × 1.55 = about 2,760 kcal

Both results sit comfortably inside the reference ranges in the table above, which is a good sign the inputs are sensible.

Step 3: Accept a margin of error

Even the best equation is an estimate. If Mifflin-St Jeor is within 10% for you, the woman in our example could really need anywhere from about 1,730 to 2,110 kcal a day. The systematic review also notes that older adults and some ethnic groups were underrepresented in the research, so errors can be larger for some people. That is why the next section matters more than the formula.

Adjust the number to your goal

Once you have a maintenance estimate, you set a daily target for what you want to achieve.

• Maintain your weight: eat around your estimated need.
• Lose weight: eat less than your need. A common approach, and the one PixNutri uses, is to subtract 500 kcal a day. For the woman above, that means about 1,420 kcal. Read more in our guide to the calorie deficit.
• Gain weight or build muscle: add a modest surplus. PixNutri adds 300 kcal a day, which keeps the gain gradual.

Do not go too low

For most adults, a target below about 1,200 kcal a day for women or 1,500 kcal a day for men makes it hard to get enough protein, vitamins and minerals, and it is hard to sustain. Aim higher than that unless a doctor or registered dietitian is supervising you. PixNutri never sets a weight-loss target below these floors.

A faster target is not always a better one. If you are wondering what a realistic pace looks like, see how fast you can lose weight safely.

Why your real number may differ from any calculator

Your daily calorie need is not fixed. Several things move it:

• Body size. A heavier body needs more energy to maintain and move. As you lose weight, your need falls, so a target that worked at 90 kg may stall you at 80 kg.
• Muscle mass. Muscle is metabolically active tissue. Two people of the same weight can have quite different needs.
• Everyday movement. Walking, standing, housework and fidgeting vary a lot between people and between days, and they are hard to capture in one activity factor.
• Age. As the reference table shows, needs typically decline slowly over the decades.
• Life stage and health. Pregnancy and breastfeeding raise needs. The DGE, for instance, suggests about 250 kcal a day extra in the second trimester and 500 kcal in the third for women who started at a healthy weight. Some medical conditions and medicines also change energy needs.

The NIDDK Body Weight Planner, a research-based tool from the US National Institutes of Health, points out another very human factor: people often underestimate how much they eat. If a target seems “too high” because you are not losing weight, it is worth checking your logging before cutting further.

How to find your true maintenance calories

The most reliable way to know how many calories you should eat a day is to test your estimate against reality for a few weeks.

1. Pick your starting target from the calculation above.
2. Log what you eat as accurately as you can for 2 to 3 weeks. Include drinks, cooking oil, sauces and snacks. Our guide on how to count calories explains how to do this without it taking over your life.
3. Weigh yourself under the same conditions (for example, in the morning after the bathroom, before breakfast) several times a week, and look at the weekly average rather than single days.
4. Compare the trend with your goal.
   • Weight stable and your goal is maintenance: your target is about right.
   • Weight falling faster than about 1 kg a week: you may be eating too little; add 100 to 200 kcal.
   • Weight not moving after 3 weeks and your goal is loss: reduce by 100 to 200 kcal or look for unlogged extras.
5. Recalculate after every few kilograms of change, because your need moves with your weight.

This is where a tracking app earns its place. In PixNutri you can photograph a meal to get an AI estimate of calories and macros, then check and correct the values and portion before saving, because photo estimates can miss hidden oil or sauce. The weight log shows your trend, so you can see whether your target is doing what you expected.

Calories are not the whole story

Hitting a calorie number with mostly biscuits is not the same as hitting it with a balanced plate. Energy intake decides whether your weight goes up or down; the quality of the food decides how full you feel, how well you perform and your long-term health. A few habits make any target easier:

• Build meals around protein, vegetables, fruit, whole grains and pulses.
• Watch liquid calories: juice, sugary drinks and alcohol add energy without much fullness.
• Keep your target realistic. A number you can live with for months beats an aggressive one you abandon in two weeks.

A note of care: if you are pregnant or breastfeeding, under 18, managing diabetes or kidney disease, taking medication that affects appetite or weight, or have a history of disordered eating, talk to a doctor or registered dietitian before setting a calorie target.

FAQ

Is 2,000 calories a day enough?

For many women it is close to maintenance, and the NHS uses 2,000 kcal as the average for women. Many men, and active women, need more. Use a personal estimate and your weight trend to check.

How many calories should I eat a day to lose weight?

Start from your estimated maintenance calories and subtract around 500 kcal a day, without going below about 1,200 kcal for women or 1,500 kcal for men unless you are medically supervised.

Why am I not losing weight on 1,200 calories?

The most common reason is that real intake is higher than logged, for example from oils, drinks, snacks or weekend meals. Day-to-day changes in body water can also mask fat loss for a while. Log carefully for a few weeks and look at your weekly average weight before cutting further.

Should I eat back the calories I burn exercising?

Your activity factor already includes regular exercise. If you add a workout on top of your usual routine, eating back part of it, rather than all, is a cautious approach, because both exercise estimates and food logs have errors.

Do calorie needs change with age?

Yes, slowly. In the DGE reference values they fall by about 100 to 200 kcal from one adult age group to the next, partly because body composition and activity change with age. Staying active and strong helps limit the drop.