Most adults need between 1,600 and 3,000 calories per day, depending on age, sex, body size, and how physically active they are. That range is wide because calorie needs are genuinely personal. A sedentary 65-year-old woman and an active 25-year-old man can differ by more than 1,000 calories a day, and both numbers are perfectly healthy.
Estimated Calories by Age, Sex, and Activity
The U.S. Dietary Guidelines provide a useful starting table. These numbers assume you’re maintaining your current weight, not trying to lose or gain.
Males
- Ages 19–25: 2,400 (sedentary) to 3,000 (active)
- Ages 26–45: 2,200–2,800, depending on activity
- Ages 46–65: 2,000–2,600
- Ages 66+: 2,000–2,600
Females
- Ages 19–25: 2,000 (sedentary) to 2,400 (active)
- Ages 26–50: 1,800–2,200
- Ages 51–65: 1,600–2,200
- Ages 66+: 1,600–2,000
“Sedentary” here means just the physical activity of daily living: cooking, walking around your house, working at a desk. “Moderately active” is the equivalent of walking 1.5 to 3 miles a day at a brisk pace on top of your normal routine. “Active” means more than 3 miles a day of walking-equivalent exercise.
How Your Body Burns Calories
Your total daily calorie burn has three main components. The largest, accounting for roughly 60–70% of the total, is your basal metabolic rate (BMR): the energy your body uses just to keep you alive while you’re doing absolutely nothing. Breathing, circulating blood, maintaining body temperature, and repairing cells all cost energy. The second component is physical activity, which can range from 15% of your total burn if you’re sedentary to 30% or more if you’re very active. The third is the thermic effect of food, the energy it takes to digest what you eat, which accounts for about 10% of total calories.
Not all foods cost the same to digest. Protein uses 15–30% of its own calories during digestion, carbohydrates use 5–10%, and fats use only 0–3%. This is one reason higher-protein diets can feel more satiating per calorie.
How to Estimate Your Personal Number
The most widely used formula in clinical nutrition is the Mifflin-St Jeor equation. It estimates your BMR based on weight, height, age, and sex. For women, it multiplies your weight in kilograms by 10, adds your height in centimeters times 6.25, subtracts your age in years times 5, then subtracts 161. For men, the formula is the same except you add 5 instead of subtracting 161.
Once you have your BMR, you multiply it by an activity factor. The Food and Agriculture Organization of the United Nations classifies these into three tiers: sedentary or lightly active (multiply by 1.4 to 1.69), moderately active (1.7 to 1.99), and vigorously active (2.0 to 2.4). Values above 2.4 are difficult to sustain over the long term. Most people with office jobs and a regular gym habit fall somewhere in the 1.5 to 1.7 range.
As a quick example: a 35-year-old woman who weighs 150 pounds (68 kg), stands 5’5″ (165 cm), and exercises a few times per week would have a BMR of roughly 1,387 calories. Multiplied by an activity factor of about 1.55, her estimated daily maintenance need is around 2,150 calories.
How Calorie Needs Change With Age
Your metabolism does slow down as you get older, but the timeline may surprise you. Research published in Science and covered by Harvard Health found that metabolic rate stays remarkably stable from about age 20 to 60 when you account for changes in body size and composition. The real decline kicks in around age 60, when both basal metabolic rate and total energy expenditure begin dropping by roughly 0.7% per year. By age 90 and beyond, total daily energy expenditure is about 26% lower than it was in middle age.
The practical takeaway: if you’re in your 30s or 40s and gaining weight, the culprit is more likely changes in activity level, diet, or body composition than a slowing metabolism. After 60, though, the decline is real and worth accounting for by either adjusting portion sizes or staying physically active to preserve muscle mass.
Calorie Targets for Weight Loss
If your goal is to lose weight, the general approach is to eat fewer calories than you burn. A deficit of about 500 calories per day translates to roughly one pound of weight loss per week. You can create that deficit by eating less, moving more, or a combination of both.
Where you set that deficit matters. Dropping too low, particularly below 1,200 calories for women or 1,500 for men, makes it hard to get adequate nutrition and often backfires by increasing hunger, fatigue, and the likelihood of regaining the weight. Chronic undereating carries real health consequences: persistent tiredness, frequent illness, slow wound healing, poor concentration, feeling cold, and low mood. Losing more than 5–10% of your body weight within 3 to 6 months without intending to is a red flag worth investigating.
A more sustainable strategy is a moderate deficit, 300 to 500 calories below your maintenance level, combined with enough protein to preserve muscle. The weight comes off more slowly, but you’re far more likely to keep it off.
Calorie Targets for Muscle Gain
Building muscle requires eating slightly more than you burn. The exact size of the surplus isn’t well established in research, but most practitioners recommend starting small, perhaps 200 to 300 extra calories per day, to minimize unnecessary fat gain. Adequate protein intake and a structured strength training program matter more than simply eating a lot. If you’re gaining more than about a pound per week, most of the extra is fat, not muscle, and you should scale back the surplus.
Calorie Needs During Pregnancy
Pregnancy increases calorie needs, but not as dramatically as people sometimes think. During the first trimester, most women don’t need extra calories at all; roughly 1,800 calories per day is typical for a normal-weight pregnant woman. In the second trimester, that rises to about 2,200 calories. By the third trimester, the target is around 2,400 calories, an increase of about 300 calories over pre-pregnancy needs. These numbers shift based on your starting weight, activity level, and whether you’re carrying multiples.
Why These Numbers Are Starting Points
Every formula and chart gives you an estimate. Your actual calorie needs depend on factors no equation fully captures: your genetics, your muscle-to-fat ratio, how well you sleep, your stress levels, and even the composition of your gut microbiome. The most reliable way to fine-tune your intake is to track your weight and energy levels over two to four weeks at a given calorie level, then adjust. If your weight is stable and you feel good, you’ve found your maintenance range. If you’re losing or gaining unintentionally, shift your intake by 200 to 300 calories and observe again.
The numbers in this article give you a solid starting point. What matters most is whether your calorie intake supports how you actually feel and function day to day.