Most adults need somewhere between 10,500 and 24,500 calories per week, depending on their size, age, sex, and how active they are. That’s a wide range because no single number works for everyone. The good news is that estimating your personal weekly target takes just a few steps, and thinking in weekly terms gives you more flexibility than obsessing over a daily number.
How to Estimate Your Weekly Calories
Your weekly calorie need is simply your daily need multiplied by seven. To find your daily number, start with your basal metabolic rate (BMR), which is the energy your body burns at complete rest just to keep your organs functioning, your blood circulating, and your cells repairing themselves. The most widely used formula, called the Mifflin-St Jeor equation, works like this:
- For men: (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) + 5
- For women: (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) − 161
That gives you your BMR. But you don’t lie in bed all day, so you multiply it by an activity factor to get your total daily energy expenditure:
- Sedentary (desk job, little exercise): BMR × 1.2
- Lightly active (light exercise 1–3 days/week): BMR × 1.375
- Moderately active (moderate exercise 3–5 days/week): BMR × 1.55
- Active (hard exercise 6–7 days/week): BMR × 1.725
- Very active (intense daily training or physical job): BMR × 1.9
Multiply that daily total by seven, and you have your weekly calorie target for maintaining your current weight.
A Quick Example
A 35-year-old woman who weighs 70 kg (about 154 pounds), stands 165 cm (5’5″), and exercises a few times a week would calculate her BMR as: (10 × 70) + (6.25 × 165) − (5 × 35) − 161 = 1,370 calories per day. Multiply by the “lightly active” factor of 1.375 and she gets roughly 1,884 daily calories, or about 13,190 calories per week to maintain her weight.
A 35-year-old man with the same height and weight would get a BMR of 1,536 (the formula adds 5 instead of subtracting 161). At the same activity level, his daily maintenance is around 2,112 calories, or about 14,780 per week. The difference between men and women shrinks as activity increases but never disappears entirely.
Weekly Calories for Weight Loss
If your goal is to lose weight, you need to create a calorie gap between what you burn and what you eat. A common starting point is cutting about 500 calories per day, which adds up to a 3,500-calorie weekly deficit and roughly one pound of fat loss per week. The CDC notes that people who lose at a steady pace of 1 to 2 pounds per week are more likely to keep the weight off long term.
Using the woman from the example above, her maintenance is about 13,190 calories per week. Subtracting 3,500 brings her weight-loss target to roughly 9,690 per week, or about 1,384 per day. That’s close to a widely recognized safety floor: women generally shouldn’t go below 1,200 calories per day (8,400 per week) and men shouldn’t drop below 1,500 per day (10,500 per week) without medical supervision. Eating too few calories makes it very difficult to get enough essential nutrients.
The old rule that 3,500 calories always equals one pound isn’t perfectly precise for every person. As you lose weight, your body adapts and burns slightly less energy, so progress often slows over time. But as a planning tool, the 500-calorie daily cut remains a practical starting point.
Why Weekly Totals Are More Useful Than Daily Ones
Real life doesn’t divide evenly into identical days. You might eat lighter on busy weekdays and have a bigger meal on Saturday night. Thinking in weekly totals lets you absorb those natural fluctuations without feeling like you’ve failed. If your weekly target is 14,000 calories, you could eat 1,800 on five days and 2,500 on two days and still land right on track.
This flexible approach, sometimes called calorie cycling, has some evidence behind it. Research suggests that alternating between higher and lower calorie days can improve diet adherence and reduce hunger compared to eating the exact same amount every day. One study found that a continuous low-calorie diet decreased metabolism by more than 100 calories within three weeks, but when participants switched to higher-calorie eating in the fourth week, their metabolic rate rebounded above where it started. Periodic higher-calorie days also appear to help preserve muscle mass during fat loss, which matters because muscle is what keeps your resting metabolism up.
The practical takeaway: pick a weekly number, distribute it across seven days in whatever pattern suits your life, and track the total rather than agonizing over any single day.
How Age Changes Your Number
Your calorie needs don’t stay fixed throughout your life. A large study published in Science found that total energy expenditure holds surprisingly steady from about age 20 through 60. The real decline begins around 60, dropping by roughly 0.7% per year. By age 90 and beyond, total energy expenditure is about 26% lower than in middle-aged adults.
This means a 45-year-old and a 30-year-old of the same size and activity level burn close to the same number of calories. But a 75-year-old will genuinely need fewer. If you’re recalculating your weekly target after a decade or two, plug your current age into the formula rather than relying on a number you figured out years ago.
Activity Makes the Biggest Difference
Looking at the multipliers, the jump from sedentary (1.2) to very active (1.9) increases your daily burn by nearly 60%. For someone with a BMR of 1,500, that’s the difference between 1,800 and 2,850 calories per day, or 12,600 versus 19,950 per week. No other single variable, not age, sex, or height, shifts the number that dramatically.
The Food and Agriculture Organization of the United Nations classifies physical activity levels into three broad bands: sedentary to light (1.4–1.69), moderately active (1.70–1.99), and vigorously active (2.0–2.4). They note that sustaining a level above 2.4 over long periods is extremely difficult, which is relevant if you’re tempted to pick the highest category. Most people with regular gym habits fall into the moderate range. Competitive athletes and those with physically demanding jobs are the ones who genuinely reach the upper tiers.
If you’re unsure where you fall, start with “lightly active” and adjust after two to three weeks based on whether your weight is trending in the direction you expect. Your scale is the ultimate reality check on any formula.