How Many Calories Should I Eat a Day?
There isn’t one calorie target that works for everyone. How many calories you should eat a day depends on factors including your age, sex, height, weight, body composition, activity level, life stage, and whether you want to lose weight, maintain your current weight, or gain weight.
A useful starting point is your Total Daily Energy Expenditure, or TDEE. TDEE estimates the number of calories you need to maintain your current weight. From there, your goal determines whether you generally need to eat below, around, or above that amount.
For a more personalized estimate, calculate your Basal Metabolic Rate (BMR) first, then use your activity level to estimate your TDEE.
A Quick Reference for Daily Calorie Needs
Not ready to run the formula? These maintenance-calorie ranges, based on age, sex, and activity level, offer a reasonable starting estimate.
| Group | Sedentary | Moderately Active | Active |
| Women, 19–30 | 1,800–2,000 | 2,000–2,200 | 2,400 |
| Women, 31–59 | 1,800 | 2,000 | 2,200 |
| Women, 60+ | 1,600 | 1,800 | 2,000–2,200 |
| Men, 19–30 | 2,400–2,600 | 2,600–2,800 | 3,000 |
| Men, 31–59 | 2,200–2,400 | 2,400–2,600 | 2,800–3,000 |
| Men, 60+ | 2,000 | 2,200 | 2,400–2,600 |
Sedentary means little movement beyond daily routine; moderately active is roughly equivalent to walking 1.5 to 3 miles a day; active means covering more than 3 miles daily. Treat these figures as a rough anchor point—the formula below is more specific to your individual statistics.
How Many Calories Should I Eat to Lose Weight?
If your goal is to lose weight, you generally eat below your TDEE, creating a calorie deficit.
A commonly used starting point is around 500 calories a day below TDEE because it can support gradual weight loss rather than an aggressive restriction that may be difficult to sustain. However, a 500-calorie deficit is not automatically the right target for every person. Your individual needs and how well you can maintain the plan should guide adjustments.
As your weight changes, your TDEE can change as well. That means a calorie target that worked at the beginning of a weight-loss phase may eventually need to be recalculated.
How Many Calories Should I Eat to Maintain My Weight?
If you want to maintain your current weight, your calorie intake should be at or near your TDEE.
TDEE represents the estimated number of calories that keeps your weight around its current level by accounting for your baseline energy needs and activity. Because your weight and activity can change over time, your maintenance calorie needs can change too.
How Many Calories Should I Eat to Gain Weight?
If your goal is to gain weight, you generally eat above your TDEE, creating a calorie surplus.
For people aiming to build muscle, a modest, controlled surplus combined with resistance training tends to favor lean gains. A large, unstructured surplus typically adds more fat than muscle.
How to Calculate Your Daily Calorie Needs
The calculation happens in two steps: estimate your BMR, then use your activity level to estimate your TDEE.
Step 1: Calculate Your Basal Metabolic Rate
Basal Metabolic Rate, or BMR, represents the calories your body burns at complete rest while carrying out essential functions.
The Mifflin-St Jeor equation provides an estimate of BMR for the general population:
Men:
(10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) + 5
Women:
(10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) − 161
Step 2: Estimate Your Total Daily Energy Expenditure
TDEE takes your BMR and factors in how much you move. Multiply your BMR by the activity level that most closely matches your routine:
| Activity Level | Multiplier |
| Sedentary — little to no exercise | × 1.2 |
| Lightly active — light exercise 1–3 days/week | × 1.375 |
| Moderately active — moderate exercise 3–5 days/week | × 1.55 |
| Very active — hard exercise 6–7 days/week | × 1.725 |
| Extremely active — physical job plus daily training | × 1.9 |
Example: Calculating Daily Calorie Needs
Consider a 30-year-old woman who weighs 65 kg and is 165 cm tall.
Her BMR calculates to roughly 1,395 calories. At moderate activity, multiplying that figure by 1.55 gives a TDEE of about 2,160 calories.
That TDEE represents her estimated maintenance baseline. If her goal is to maintain her weight, she would generally aim around that amount. If her goal is to lose or gain weight, she would adjust her intake up or down depending on the goal.
What Affects How Many Calories You Need?
Two people can use the same formula and arrive at very different calorie needs because several variables affect BMR and TDEE.
Age
Age matters because metabolism slows and muscle mass naturally decreases over time, lowering baseline calorie burn.
Sex
Men typically need more calories than women at an equivalent age and activity level, largely because of differences in average body size and muscle mass.
Height and Weight
Height and weight affect calorie needs because larger bodies generally burn more energy at rest.
Body Composition
Body composition also matters. Muscle tissue uses more energy than fat while inactive, so two people at the same weight can have different calorie requirements depending on their body composition.
Activity Level
Activity level can substantially change daily calorie needs. Moving from a sedentary routine to a consistently active one can shift daily requirements by several hundred calories.
Life Stage
Life stage adds further variation. Pregnancy and breastfeeding typically raise calorie requirements above baseline, while older adults generally need less than younger adults at matching activity levels, mostly because of gradual muscle loss.
Does Keto, Vegan Eating, or a Restricted Diet Change Your Calorie Needs?
Keto, vegan, low-carb, or a diet prescribed for a medical condition does not change your underlying BMR or TDEE. What changes is how you obtain your calories within the requirements of that diet.
Vegan eating can make it harder to reach higher calorie or protein targets unless meals are deliberately built around calorie-dense plant foods. Keto and other very low-carbohydrate approaches may require closer attention to fat intake to keep total calories adequate.
If you are managing a medical condition such as kidney disease or diabetes, a registered dietitian should confirm your calorie target directly because generic formulas are not designed to account for medical complexity.
What Is the Lowest Number of Calories You Should Eat?
Very low-calorie diets require caution. Generic calorie formulas are estimates, and a calorie target that is too restrictive can make it difficult to meet nutritional needs and sustain an eating plan.
General guidance has often placed minimum daily intake around 1,200 calories for adult women and 1,500 for adult men, with lower intakes requiring direct medical supervision. Staying below these levels for an extended period can be associated with problems including insufficient food intake, nutrient deficiencies, muscle loss, persistent hunger, unusual fatigue, and weight regain.
If your calculated calorie target requires a very low intake, don’t simply reduce calories further on your own. Medical or nutrition guidance may be appropriate, particularly when a medical condition or other special circumstance affects your nutritional needs.
Are Calorie Calculators Accurate?
BMR and TDEE calculations provide estimates rather than exact measurements of your daily energy expenditure.
Your calorie needs can change as your body weight, activity level, body composition, and life stage change. That is why a calorie target should be treated as a starting point rather than a permanent number.
If you are actively losing or gaining weight, rechecking your TDEE every few weeks can help keep your target aligned with your changing needs.
Common Calorie-Tracking Mistakes
Even a correctly calculated calorie target can be undermined by inaccurate tracking.
Common problems include:
- Underestimating portions of calorie-dense foods such as oils and dressings
- Forgetting to log drinks
- Forgetting cooking fats
- Allowing your calorie target to become outdated as your weight changes
- Assuming that “calories in, calories out” tells the entire story of a sustainable eating pattern
Food quality can also influence hunger levels and how sustainable a plan feels. Rechecking your TDEE as your weight changes helps keep your calorie target current.
Frequently Asked Questions
How do I know if I should aim for a deficit, maintenance, or a surplus?
It depends on your goal. A deficit is generally used for weight loss; maintenance calories are used to hold weight steady; and a surplus is used to gain weight or muscle.
What’s the difference between BMR and TDEE in practice?
BMR is the number of calories your body burns at complete rest while performing essential functions. TDEE adds your activity level to that baseline and provides an estimate of your daily maintenance calorie needs.
Is 500 calories below TDEE always the right deficit?
No. Around 500 calories below TDEE is a commonly used starting benchmark for gradual weight loss, but individual needs and adherence should guide adjustments.
Why do two people at the same weight sometimes need different calories?
Body composition can differ. Muscle uses more energy at rest than fat, so someone with more muscle mass typically needs more calories even when two people weigh the same.
Does being on keto or vegan eating change my calorie target?
No. Your BMR and TDEE stay the same; what changes is how you source those calories within the structure of the diet.
What’s the lowest number of calories considered safe?
General guidance puts the figure at roughly 1,200 calories a day for women and 1,500 for men, with lower intake requiring medical supervision. These figures should not be treated as a universal target for every person.
How can I tell if I’m undereating?
Persistent hunger, unusual fatigue, or losing weight much faster than your calculated deficit predicts can be warning signs that your intake may be too low.
Why does my calorie target need to be recalculated over time?
TDEE shifts as your body weight changes, so a calorie target that worked initially can become outdated as you lose or gain weight.
Does age lower how many calories I need?
Yes. Calorie needs generally decrease with age because metabolism slows and natural muscle loss can reduce baseline calorie expenditure.
What’s the biggest factor that changes daily calorie needs?
Activity level can have a substantial effect on daily calorie requirements and can shift estimated needs by several hundred calories a day.