Calorie Intake Calculator

🔥

Calorie Intake Calculator

Find your BMR, TDEE, and personalised calorie targets for weight loss, maintenance, or muscle gain.

⚙️ Your Details
📊 Your Results
BMR
—
kcal / day at rest
TDEE
—
kcal / day total burn
Maintenance
—
kcal / day
Weight Loss
—
kcal / day (−500)
Muscle Gain
—
kcal / day (+300)
🥗 Estimated Daily Macros (at maintenance)
Protein
—
— kcal
Carbs
—
— kcal
Fats
—
— kcal
📖 What Do These Numbers Mean?

BMR (Basal Metabolic Rate) is the number of calories your body needs just to stay alive while at complete rest — keeping your heart beating, lungs breathing, and organs functioning. Think of it as your engine idling.

TDEE (Total Daily Energy Expenditure) is your BMR multiplied by your activity factor. It represents the total calories you burn in a typical day, including movement, exercise, and daily tasks.

Maintenance calories equal your TDEE — eating at this level keeps your weight stable. Going below leads to fat loss; going above leads to weight or muscle gain.

Mifflin-St Jeor Equation Science-backed formula Personalized to you

How Many Calories Should I Eat?

Calories are a measurement of energy. Every bite of food you eat contains energy, and your body uses that energy to fuel everything from breathing and thinking to running and lifting weights. Understanding how many calories you need is one of the most powerful steps you can take for your health.

The answer is not a single fixed number. Your ideal daily calorie intake depends on several personal factors: your age, sex, height, weight, and how active you are each day. That is why calculators like this one use a proven scientific formula — the Mifflin-St Jeor equation — rather than a generic one-size-fits-all target.

The Mifflin-St Jeor Equation Explained

Developed in 1990, the Mifflin-St Jeor equation is considered the most accurate way to estimate your Basal Metabolic Rate (BMR) for most healthy adults. Unlike older formulas, it accounts for modern body compositions and has been validated across large populations.

  • For men: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5
  • For women: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161

Your BMR is then multiplied by an activity factor (ranging from 1.2 for sedentary to 1.9 for extremely active) to give your TDEE — the total calories your body burns every day.

Calories for Weight Loss

To lose weight, you need to consume fewer calories than you burn — this is called a calorie deficit. A deficit of around 500 calories per day is generally recommended because it leads to approximately 0.5–1 pound (0.25–0.45 kg) of fat loss per week, which is a sustainable pace that preserves muscle tissue.

Crash diets that cut calories too aggressively can cause muscle loss, nutritional deficiencies, slowed metabolism, and rebound weight gain. Slow and steady always wins the race when it comes to lasting fat loss.

Calories for Muscle Gain

Building muscle requires extra energy. A modest surplus of 250–500 calories above maintenance gives your body the building blocks it needs to repair and grow muscle tissue after resistance training. This calculator uses a +300 calorie surplus as a middle-ground "lean bulk" target that promotes muscle growth while minimising unwanted fat gain.

Calories for Maintenance

If you are happy with your current weight and body composition, eating at your TDEE (maintenance calories) keeps the scale steady. This is also a great target when you are focused on performance — fueling workouts without gaining or losing weight.

The Role of Macronutrients

Not all calories are equal. The three macronutrients — protein, carbohydrates, and fats — each play a distinct role in your body:

  • Protein (4 kcal/g): Builds and repairs muscle, keeps you feeling full, and supports immune function. Aim for 0.7–1g per pound of body weight.
  • Carbohydrates (4 kcal/g): Your primary energy source for brain function and exercise. Choose whole grains, fruits, and vegetables.
  • Fats (9 kcal/g): Essential for hormone production, vitamin absorption, and joint health. Focus on healthy fats from nuts, seeds, avocado, and oily fish.

Factors That Affect Your Calorie Needs

Your calorie needs are not static — they shift based on:

  • Age: Metabolism naturally slows as you age, particularly after 30.
  • Muscle mass: Muscle burns more calories at rest than fat tissue.
  • Hormones: Thyroid function, insulin sensitivity, and reproductive hormones all influence metabolism.
  • Sleep: Poor sleep raises hunger hormones (ghrelin) and lowers satiety hormones (leptin).
  • Stress: Chronic stress elevates cortisol, which can increase appetite and fat storage.

Tips for Hitting Your Calorie Target

Knowing your target is half the battle. Here is how to stay on track:

  • Use a food scale to weigh portions accurately — eyeballing is notoriously inaccurate.
  • Track meals in a nutrition app for at least a few weeks to build awareness.
  • Prioritise whole, minimally processed foods that are naturally filling and nutrient-dense.
  • Eat protein at every meal to curb cravings and support muscle retention.
  • Stay hydrated — thirst is often mistaken for hunger.
  • Reassess your targets every 4–6 weeks as your weight changes.

When to See a Professional

This calculator is a great starting point, but it is an estimate. If you have a medical condition, are pregnant or breastfeeding, or have a history of disordered eating, always consult a registered dietitian or your healthcare provider before making significant changes to your diet.

❓ Frequently Asked Questions

What is a calorie? +
A calorie (technically a kilocalorie, or kcal) is a unit of energy. In nutrition, it measures how much energy a food provides to your body. Your body uses this energy for every function — from breathing and digesting food to exercising and thinking.
How accurate is this calorie calculator? +
This calculator uses the Mifflin-St Jeor equation, which research consistently shows to be the most accurate formula for estimating BMR in the general population — typically within 10% of your true metabolic rate. However, individual variation exists. Use the result as a starting point, track your weight for 2–3 weeks, then adjust calories by 100–200 kcal if needed.
What is the difference between BMR and TDEE? +
BMR (Basal Metabolic Rate) is the calories your body burns at complete rest — just to keep organs functioning. TDEE (Total Daily Energy Expenditure) takes BMR and multiplies it by your activity level to account for all the calories you burn through daily movement, exercise, and digestion.
How many calories should I eat to lose weight? +
A deficit of 500 calories per day below your TDEE typically results in about 1 pound (0.45 kg) of fat loss per week. This is considered a safe and sustainable rate. Avoid going below 1,200 kcal/day for women or 1,500 kcal/day for men without medical supervision, as very low calorie intakes can lead to muscle loss and nutrient deficiencies.
How many calories do I need to build muscle? +
To build muscle efficiently, most people benefit from a calorie surplus of 250–500 kcal above maintenance combined with consistent resistance training and adequate protein intake (around 0.7–1g per pound of bodyweight). Eating at a smaller surplus — as this calculator suggests with +300 kcal — is often called a "lean bulk" and minimises unnecessary fat gain.
Why am I not losing weight even though I eat at a deficit? +
Several factors can stall weight loss: underestimating portion sizes (the most common culprit — a food scale helps), metabolic adaptation over time, water retention from sodium, hormonal fluctuations, or overestimating calories burned during exercise. Reassess your intake, weigh food accurately, and ensure you're truly in a consistent deficit before assuming something else is wrong.
Should I eat back calories I burn during exercise? +
This depends on which activity multiplier you chose. If you selected an activity level that reflects your exercise habits, your TDEE already accounts for those burned calories, so you should not eat them back separately. If you chose "sedentary" and then exercise, you may eat back a portion (50–75%) of those burned calories, since fitness trackers tend to overestimate burn.
Does eating fewer calories slow down my metabolism? +
Yes — when you eat in a significant calorie deficit, your body adapts by reducing the energy it expends, a process called "metabolic adaptation." This is why weight loss often slows over time. Strategies to minimise this include preserving muscle through resistance training, eating adequate protein, taking periodic diet breaks at maintenance calories, and losing weight gradually.
How often should I recalculate my calorie needs? +
Recalculate your BMR and TDEE every 4–6 weeks, or whenever your weight changes by more than 5–10 lbs (2–4 kg). As you lose weight, your calorie needs decrease because there is less body mass to maintain. Updating your targets keeps you on track and avoids unnecessary plateaus.
Is counting calories necessary to lose weight? +
Not necessarily. Many people lose weight successfully through mindful eating, portion control, and choosing whole foods without ever counting a calorie. However, tracking calories — even temporarily — builds awareness of what you're eating and is one of the most evidence-backed strategies for weight management. A hybrid approach works well for most: track loosely, use a food scale for high-calorie foods, and prioritise protein and fibre.
What activity level should I choose? +
Most people over-estimate their activity level. Choose "sedentary" if you have a desk job and don't exercise. Choose "lightly active" if you walk regularly or exercise 1–2 times a week. "Moderately active" suits 3–5 workouts per week. "Very active" fits daily intense training. "Extra active" is reserved for athletes in heavy training or people with physically demanding jobs. When in doubt, go one level lower — you can always eat more if the deficit is too aggressive.

⚠️ Medical Disclaimer

The information and calorie estimates provided by this tool are for general educational purposes only and do not constitute medical or nutritional advice. This calculator uses the Mifflin-St Jeor equation, which provides estimates based on population averages. Individual metabolic needs can vary significantly. Results should not be used to diagnose, treat, cure, or prevent any health condition. Always consult a qualified healthcare provider, physician, or registered dietitian before making significant changes to your diet, especially if you have an underlying health condition, are pregnant, breastfeeding, or have a history of disordered eating.

Medical Disclaimer: The calculators and content on Widjaja Studio are provided for educational and informational purposes only and should not be considered medical advice. Always consult a qualified healthcare professional regarding your individual health needs.


Disclosure: As an Amazon Associate, we earn from qualifying purchases at no additional cost to you.

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