How do you calculate the amount of calories I need to eat?

Determining how many calories you need each day is an important part of managing your weight and overall health. The number of calories you need depends on your age, sex, height, weight, activity level, and goals. While online calculators can provide estimates, your individual calorie needs may vary.

What are calories?

Calories are a measure of the energy in food. Consuming more calories than your body burns leads to weight gain, while consuming fewer calories than you burn leads to weight loss. To maintain your current weight, you need to balance the calories consumed through food and drink with the calories utilized by your body.

Basic calorie calculations

As a starting point, the Dietary Guidelines for Americans recommends the following calorie intakes:

  • Women: 2,000 calories per day
  • Men: 2,500 calories per day

However, within these recommendations, your individual needs may be higher or lower depending on your body, activity level, and goals. More precise calorie estimates can be obtained by factoring in your:

  • Age
  • Sex
  • Height
  • Current weight
  • Activity level
  • Goals for weight loss or gain

Calculating your basal metabolic rate

Your basal metabolic rate (BMR) is the minimum number of calories your body needs to perform essential functions like breathing, circulating blood, adjusting hormone levels, and maintaining cell function. It does not include the calories needed for daily activities and exercise.

You can estimate your BMR using the following formulas:

For women:

BMR = 655 + (4.35 x weight in pounds) + (4.7 x height in inches) – (4.7 x age in years)

For men:

BMR = 66 + (6.23 x weight in pounds) + (12.7 x height in inches) – (6.8 x age in year)

So for example, a 40-year-old woman who is 5’6″ (66 inches) and weighs 150 pounds would calculate her BMR as follows:

BMR = 655 + (4.35 x 150) + (4.7 x 66) – (4.7 x 40)

= 655 + 652.5 + 310.2 – 188

= 1429.7 calories

This BMR of around 1430 calories would be the starting point for this woman to determine her total daily calorie needs.

Factoring in your activity level

After calculating your BMR, you then need to factor in your activity level to estimate your total daily calorie expenditure, or TDEE (total daily energy expenditure). To determine TDEE, multiply your BMR by an activity factor:

  • Sedentary (little or no exercise): BMR x 1.2
  • Lightly active (light exercise 1-3 days/week): BMR x 1.375
  • Moderately active (moderate exercise 3-5 days/week): BMR x 1.55
  • Very active (hard exercise 6-7 days/week): BMR x 1.725
  • Extremely active (very hard exercise and physical job): BMR x 1.9

For the example above of a sedentary 40-year-old woman with a BMR of 1430 calories, her estimated TDEE would be:

TDEE = BMR x activity factor
= 1430 x 1.2
= 1716 calories

So if this woman is sedentary, her estimated calorie needs would be around 1716 calories per day. If she exercised moderately 3-5 days per week, her TDEE would be higher at around 2216 calories per day (BMR x 1.55).

Adjusting for weight loss or gain goals

To lose weight, you need to consume fewer calories than your body burns each day. To gain weight, you need to consume more. Here are some general guidelines for adjusting your calorie intake to meet weight goals:

To lose 1 pound per week:

  • Reduce daily calorie intake by 500 calories

To lose 2 pounds per week:

  • Reduce daily calorie intake by 1,000 calories

To gain 1 pound per week:

  • Increase daily calorie intake by 500 calories

To gain 2 pounds per week:

  • Increase daily calorie intake by 1,000 calories

However, women should not consume fewer than 1200 calories daily and men no less than 1500 calories unless supervised by a doctor for medical weight loss.

Using online calculators

If performing these calculations seems complicated, you can get an estimate of your calorie needs using an online calorie calculator. These calculators allow you to plug in information like your age, sex, height, weight and activity level to determine a calorie target. Be sure to use your actual body weight, not your ideal weight, to get the most accurate result.

Online calculators can provide a good starting point, but you may need to adjust your calories up or down depending on your individual needs and results. Track your calorie intake and weight changes for a few weeks to fine-tune your numbers.

Additional factors that influence calorie needs

While standard calculations account for age, sex, height, weight, and activity level, other individual factors can also impact calorie needs and should be considered:

  • Muscle mass: Those with more muscle mass burn more calories at rest, so they may require more calories.
  • Health conditions: Illnesses or chronic conditions may increase calorie needs.
  • Metabolic factors: Your metabolism may run faster or slower than average.
  • Stress levels: High stress can increase levels of calorie-burning hormones.
  • Body composition: Higher or lower percentages of fat and muscle can influence metabolic rate and calorie needs.
  • Age: Calorie burn tends to decrease with age due to loss of muscle.

Pay attention to your energy levels, hunger cues, and rate of weight loss/gain to determine if you need to adjust your calorie intake based on your individual situation.

Sample calorie calculations

To illustrate how these calculations work, here are some examples of determining calorie needs for three hypothetical individuals:

Example 1: Calculating BMR

John is a 28-year-old man who is 5’10” and weighs 172 pounds. Using the BMR formula for men, his calculation would be:

BMR = 66 + (6.23 x 172) + (12.7 x 70) – (6.8 x 28)

= 66 + 1071 + 889 – 190.4

= 1836 calories

John’s estimated BMR is around 1836 calories per day.

Example 2: Factoring in activity level

Emily is a 32-year-old woman who is 5’5″ and 126 pounds. Her calculated BMR is 1314 calories per day. Emily exercises for 60-90 minutes 5 days per week. For her activity level, she would multiply her BMR by 1.55.

TDEE = BMR x Activity Factor

= 1314 x 1.55

= 2036 calories

With her activity level, Emily’s estimated daily calorie needs are around 2036 calories per day.

Example 3: Adjusting for weight loss

Chris is a 50-year-old man who is 6’0″ and 233 pounds. He wants to lose 1 pound per week. His estimated BMR is 1893 calories per day. As a moderately active person, his TDEE is estimated at 2126 calories (1.55 x BMR).

To lose 1 pound per week, Chris should reduce his calories by 500 per day:

2,126 TDEE
– 500 calorie deficit
= 1,626 calories per day

Chris should aim for around 1626 calories daily to lose 1 pound per week based on his calculated calorie needs.

Key takeaways on calculating calorie needs

  • Calculate your BMR using your age, sex, height, and weight, then multiply by an activity factor to estimate your TDEE.
  • Adjust your calories up or down from your TDEE to meet weight loss or gain goals.
  • Use online calculators for an estimate, but you may need to refine your numbers over time.
  • Factor in individual variations in muscle mass, health, metabolism, stress, and body composition.
  • Track your intake and weight changes to fine-tune your calorie needs as needed.

Healthy approaches to meeting your needs

Once you have an estimate for your calorie needs, the next step is meeting those needs in a healthy, sustainable way. Here are some tips:

  • Focus on whole, minimally processed foods like vegetables, fruits, lean proteins, whole grains, and healthy fats.
  • Incorporate foods you enjoy in moderation to prevent feelings of deprivation.
  • Pay attention to portion sizes using measuring cups and scales.
  • Read nutrition labels to understand calorie content.
  • Cook meals at home as often as possible for control over ingredients.
  • Meal prep and plan ahead to set yourself up for success.
  • Drink mainly water and limit sugary beverages like soda and juice.
  • Aim for consistency with your intake day-to-day and week-to-week.

Reaching your calorie goals doesn’t need to be complicated or restrictive. With some planning and mindful eating, you can craft a dietary pattern to suit your individual calorie needs and support your health.


Determining your calorie needs involves calculations based on your BMR and activity level, adjusted to meet weight goals. While estimations from formulas and online calculators can provide a starting point, your individual requirements may vary based on factors like muscle mass, health conditions, metabolism, stress, and body composition. Track your intake and weight over time to fine-tune your numbers. Focus on meeting your needs through balanced, whole foods for optimal health.

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