Why are my calorie needs different from someone my same weight?

Age, height, sex, and activity level all affect calorie needs independently of weight. Two people who weigh the same but differ in height, age, or activity level will have meaningfully different calorie requirements. Muscle mass also matters, since muscle burns more energy at rest than fat.

Is 1200 calories a day safe?

For most adults, 1200 calories is below recommended minimums and may cause muscle loss, nutrient deficiencies, and metabolic slowdown. Consult a doctor or nutritionist before going below your calculated needs by more than 500 calories, and prioritise protein and whole foods if you do eat at a low intake for a short period.

Do I need to count calories to lose weight?

Not necessarily. Calorie awareness helps you understand portion sizes and food choices. Many people lose weight successfully by focusing on food quality and portion control without strict calorie counting. Tracking for a week or two is a useful education even if you do not continue it long term.

How does physical activity affect my calorie needs?

Activity multiplies your base metabolic rate significantly. A sedentary person multiplies their BMR by 1.2. A very active person multiplies by 1.725. This difference can amount to 800 or more calories per day between the least and most active lifestyles, which is why an honest activity selection matters more than the exact formula used.

Why are my calorie needs different from someone my same weight?

Age, height, sex, and activity level all affect calorie needs independently of weight. Two people who weigh the same but differ in height, age, or activity level will have meaningfully different calorie requirements. Muscle mass also matters, since muscle burns more energy at rest than fat.

Is 1200 calories a day safe?

For most adults, 1200 calories is below recommended minimums and may cause muscle loss, nutrient deficiencies, and metabolic slowdown. Consult a doctor or nutritionist before going below your calculated needs by more than 500 calories, and prioritise protein and whole foods if you do eat at a low intake for a short period.

Do I need to count calories to lose weight?

Not necessarily. Calorie awareness helps you understand portion sizes and food choices. Many people lose weight successfully by focusing on food quality and portion control without strict calorie counting. Tracking for a week or two is a useful education even if you do not continue it long term.

How does physical activity affect my calorie needs?

Activity multiplies your base metabolic rate significantly. A sedentary person multiplies their BMR by 1.2. A very active person multiplies by 1.725. This difference can amount to 800 or more calories per day between the least and most active lifestyles, which is why an honest activity selection matters more than the exact formula used.

Health

Daily Calorie Calculator

Estimate daily calories needed for your goals.

Enter details

Based on Mifflin, St Jeor (default), Harris, Benedict, or Katch, McArdle

Sex

Age

yrs

Height

Weight

Activity level

Moderate exercise 3 to 5 days/week

Goal

Eat at TDEE

Formula

Result

Target daily calories

2,523 kcal

Maintain weight

BMR

1,628 kcal

At complete rest

TDEE

2,523 kcal

Maintenance

Suggested macros

112g

Protein

361g

Carbs

70g

Fat

Protein scaled to body weight; fat at 25% of calories; remaining calories as carbs.

How it works

We first compute your BMR (Basal Metabolic Rate, calories burned at rest), multiply by an activity factor to get TDEE (Total Daily Energy Expenditure), then add or subtract calories based on your goal.

Mifflin, St Jeor:
BMR = 10·kg + 6.25·cm − 5·age + 5
    = 10·70 + 6.25·170 − 5·28 + 5
    = 1628 kcal

TDEE = BMR × 1.55 = 2523 kcal
Target = TDEE + 0 = 2523 kcal

Activity multipliers:

×1.2Sedentary: Little or no exercise, desk job
×1.375Lightly active: Light exercise 1 to 3 days/week
×1.55Moderately active: Moderate exercise 3 to 5 days/week
×1.725Very active: Hard exercise 6 to 7 days/week
×1.9Extra active: Very hard exercise + physical job

These numbers are estimates. Track your weight for 2 to 3 weeks and adjust by ±100 to 200 kcal if you're not seeing the expected change. Consult a registered dietitian for medical conditions.

Basics

What Is a Calorie?

A calorie is a unit of energy. In nutrition, calories measure how much energy food and drinks provide to your body. Your body uses this energy for everything from breathing and circulation to physical activity and digestion.

Because calories are simply energy, the balance between what you eat and what you burn determines whether your weight goes down, stays the same, or goes up over time. Knowing your daily requirement turns that balance from guesswork into a number you can plan around.

Step-by-step

How to use this calculator

1Enter your age, sex, height, and current weight, since all four change your metabolic rate independently.
2Select the activity level that honestly reflects your typical week, including work, walking, and training.
3Read your Total Daily Energy Expenditure (TDEE), which is the calorie level that maintains your current weight.
4Choose your goal and adjust from that figure: subtract 300 to 500 calories to lose weight, or add 300 to 500 to gain.
5Recalculate every few weeks as your weight or activity level changes so your target stays accurate.

Methodology

How Your Daily Calorie Needs Are Calculated

This calculator uses the Mifflin-St Jeor equation, the most accurate widely available formula for estimating resting metabolic rate, then multiplies by an activity factor to give your Total Daily Energy Expenditure (TDEE). Your TDEE is the total calories your body needs to maintain your current weight.

The resting metabolic rate accounts for the energy your body uses at complete rest to keep your organs, brain, and temperature running. The activity multiplier then scales that figure to reflect movement, exercise, and the energy cost of digesting food, producing a realistic daily total rather than a bare minimum.

Targets

Calorie Needs by Goal

To lose weight: eat 300 to 500 calories below your TDEE
To maintain weight: eat at your TDEE
To gain weight: eat 300 to 500 calories above your TDEE

More Tools

Related tools

BMI Calculator

Check your Body Mass Index from your height and weight and see which range you fall in.

Try it

Water Intake Calculator

Find your personalised daily hydration target based on weight, activity, and climate.

Try it

Unit Converter

Convert kilograms to pounds, centimetres to feet, and many more units instantly.

Try it

FAQ