How many calories should I eat a day? A 3-step calculation
October 6, 2026 · 3 min read
Short answer: most adults need somewhere between 1,600 and 3,000 calories a day. The range is that wide because your number depends on your height, weight, age, sex and how much you move. The three steps below get you a personal figure in a couple of minutes.
Step 1: Estimate your resting metabolism (BMR)
BMR is the energy your body burns just staying alive. The most widely used formula is the Mifflin-St Jeor equation:
- 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
Example: a 30-year-old woman, 165 cm (5'5"), 65 kg (143 lb): (10 × 65) + (6.25 × 165) − (5 × 30) − 161 = about 1,370 calories.
There is more on this number in basal metabolic rate explained.
Step 2: Multiply by your activity level
Multiply BMR by the factor that matches your week to get your total daily energy expenditure (TDEE):
| Activity level | Multiplier |
|---|---|
| Sedentary (desk job, no exercise) | 1.2 |
| Lightly active (exercise 1–3 days a week) | 1.375 |
| Moderately active (exercise 3–5 days a week) | 1.55 |
| Very active (exercise 6–7 days a week) | 1.725 |
| Extra active (physical job plus training) | 1.9 |
For the same person at "lightly active": 1,370 × 1.375 = about 1,880 calories. That is the amount that keeps her weight stable.
Most people overestimate their activity. If you are torn between two levels, pick the lower one.
Step 3: Adjust for your goal
- Maintain weight: eat at your TDEE.
- Lose weight: subtract 300–500 calories. A 500-calorie daily deficit works out to roughly 1 lb (0.45 kg) a week. See the calorie deficit guide for the details.
- Gain weight or build muscle: add 250–500 calories.
So the woman in the example would aim for around 1,400–1,550 calories a day to lose weight.
Worked examples
| Profile | BMR | Maintenance (TDEE) | Weight-loss target |
|---|---|---|---|
| Woman, 30, 165 cm, 65 kg, lightly active | 1,370 | 1,880 | 1,400–1,550 |
| Man, 30, 180 cm, 80 kg, moderately active | 1,780 | 2,760 | 2,250–2,450 |
How accurate is this number?
The equation is an estimate, and your real expenditure can differ by around 10 percent. The reliable approach is to treat the result as a starting point, track your intake and weight for 2–3 weeks, and then nudge the target by 100–200 calories based on what actually happens.
As a general rule, women are advised not to go below 1,200 calories a day and men not below 1,500 unless a health professional says otherwise. If you are pregnant, breastfeeding, managing a medical condition or have a history of disordered eating, set your target with your doctor or a registered dietitian.
If you would rather not do the maths
Cal Crew asks the same questions on first launch (height, weight, age, sex, activity) and sets your daily calorie and macro targets for you. You can try the calculator on the home page right now. After that the only job left is logging your meals, and the fastest way to do that is to take a photo of your plate.