The short answer for most adults is somewhere between 1,600 and 3,000 calories a day, which is a range so wide it's useless until you narrow it. Yours depends on four things: your sex, your age, your size, and how much you move. Plug those into one well-tested equation and you get a number good to within about 10%, which is plenty to start with. Here's the math, the official guideline ranges, and how to adjust once the scale starts talking back.
Your daily burn, called TDEE (total daily energy expenditure), has three main parts. The biggest is BMR, basal metabolic rate: the cost of being alive, running your brain, heart, kidneys, and temperature regulation at complete rest. It typically accounts for 60 to 70% of the total. On top of that sits activity, both workouts and the mundane movement known as NEAT, walking, fidgeting, standing. The smallest slice is the thermic effect of food, the energy spent digesting what you eat, around 10% of intake.
Two people with identical stats can maintain on surprisingly different intakes because NEAT varies by hundreds of calories between individuals. It's one reason the calculator's answer is a starting estimate rather than a verdict.
The standard tool is the Mifflin-St Jeor equation, published in 1990 and recommended for healthy adults by the Academy of Nutrition and Dietetics. It estimates BMR from four inputs:
Then multiply by an activity factor, from 1.2 for sedentary up to 1.9 for hard daily training or a physical job. Worked example: a 35-year-old man, 175 lb (79.4 kg), 5'10" (178 cm). BMR = 794 + 1112.5 − 175 + 5 = 1,736 kcal. At moderate activity (1.55), his maintenance is 1,736 × 1.55 ≈ 2,690 calories a day. The calorie calculator runs this arithmetic, plus loss and gain targets, in one step.
The Dietary Guidelines for Americans publish estimated needs by age and sex, and they're a useful sanity check on any formula. Estimated ranges for adults, spanning sedentary through active:
| Group | Estimated calories per day |
|---|---|
| Women, 19–30 | 1,800 – 2,400 |
| Women, 31–59 | 1,800 – 2,200 |
| Women, 60+ | 1,600 – 2,000 |
| Men, 19–30 | 2,400 – 3,000 |
| Men, 31–59 | 2,200 – 3,000 |
| Men, 60+ | 2,000 – 2,600 |
Notice how wide each band is: the difference between sedentary and active is 400 to 600 calories a day for the same person, larger than most people's entire weight-loss deficit. Honesty about your activity level matters more than precision anywhere else in the calculation.
Take our example man (BMR 1,736) and walk him up the multiplier ladder:
| Activity level | Multiplier | Maintenance calories |
|---|---|---|
| Sedentary (desk job, little exercise) | 1.2 | ~2,080 |
| Light (exercise 1–3 days/week) | 1.375 | ~2,390 |
| Moderate (exercise 3–5 days/week) | 1.55 | ~2,690 |
| Active (exercise 6–7 days/week) | 1.725 | ~3,000 |
| Very active (hard training or physical job) | 1.9 | ~3,300 |
One caution: people overestimate here almost universally. If you sit for work, drive everywhere, and hit the gym three evenings, "light" is your honest answer, not "moderate." Picking one notch too high quietly adds 300 calories a day to your "maintenance," which is enough to stall a diet completely.
Enter sex, age, height, weight, and activity to see your BMR, maintenance calories, and loss/gain targets.
Calorie Calculator →A pound of body fat stores roughly 3,500 calories, so the classic arithmetic is clean: subtract 500 a day to lose about a pound a week. From a 2,690 maintenance that means eating around 2,190. Real bodies aren't quite so tidy, they adapt and slow somewhat as they shrink, but the table is still the right place to start:
| Daily intake (from 2,690 maintenance) | Deficit | Expected pace |
|---|---|---|
| 2,440 | 250 kcal | ~0.5 lb/week |
| 2,190 | 500 kcal | ~1 lb/week |
| 1,940 | 750 kcal | ~1.5 lb/week |
| 1,690 | 1,000 kcal | ~2 lb/week |
Two guardrails. First, the floors: 1,200 calories for women and 1,500 for men are the commonly cited minimums without medical supervision, and they exist because below that it gets hard to cover protein and micronutrients. Second, faster isn't better: a gentler deficit preserves muscle and sanity, and 0.5 to 1% of body weight per week is the range that tends to actually stick. For the full mechanics of deficits, the calorie deficit calculator breaks the timeline down by goal date.
Surprisingly few. Muscle is expensive to build but slow, so a surplus of 250 to 500 calories a day, protein around 0.7 to 1 g per pound of body weight, and progressive resistance training do the work. Eating thousands over maintenance mostly accelerates fat gain, not muscle. Beginners can add a pound or two of muscle a month under good conditions; experienced lifters add less. Patience is cheaper than the extra calories.
Because the estimate has error bars and so does your tracking. The formulas land within about 10% for most people, food logging under-reports by 20% or more in validation studies, and body water swings a kilogram or more day to day with sodium and carbs. None of that breaks the system; it just means you calibrate. Eat at the calculated number for two to three weeks, weigh daily but judge only weekly averages, then adjust by 100 to 200 calories in whatever direction the trend points. Your own data beats any equation, including this one.
Your number comes from sex, age, size, and honest activity: for most adults it lands between 1,600 and 3,000 calories a day. Subtract 250 to 500 for loss, add 250 to 500 with training for gain, respect the floors, and let three weeks of scale data fine-tune the estimate. For everything beyond calories, the BMR calculator isolates the resting burn, and the macro calculator splits your target into protein, carbs, and fat.
1,200 is the floor most health authorities cite for women, and 1,500 for men; going below those without a doctor or dietitian involved risks skimping on protein and micronutrients. It's also unnecessarily low for most active people, whose maintenance needs run far higher and who can lose weight steadily at 1,800 to 2,200.
Usually no, if you picked the right activity multiplier. The moderate category already assumes exercise three to five days a week, so logging a workout on top of that double-counts it. The exception is genuine one-off volume, like a long race day or a hard manual-labor shift, where a few hundred extra calories protect performance and recovery.
Three common reasons: the estimate is off for you personally (metabolism varies by about 10% around the formulas), the intake logging is off (people under-report by 20% or more in studies), or two weeks simply isn't enough time for water swings to settle. Hold intake steady for three weeks, use weekly weight averages, then adjust by 100 to 200 calories based on the trend.
They drift down slowly, roughly 5 calories per year by the equation, mostly from lean mass that quietly leaves unless you strength train. The bigger drops come from lifestyle changes, not birthdays: a 60-year-old who lifts and walks daily often needs more calories than a sedentary 35-year-old. Re-run your numbers after any 5 kg weight change or major activity shift.