About this tool
The Calorie Calculator estimates how many calories you need per day based on your age, gender, height, weight, and activity level. It uses the Mifflin-St Jeor equation - the most accurate BMR formula validated against indirect calorimetry - to calculate your Basal Metabolic Rate (BMR), then multiplies it by an activity factor to get your Total Daily Energy Expenditure (TDEE).
You can set a weight goal (lose 0.5 kg/week, maintain, or gain 0.5 kg/week), and the tool adjusts your calorie target by ±500 kcal/day accordingly. It also provides a default macro split of 40% carbohydrates, 30% protein, and 30% fat - a balanced ratio suitable for most adults.
All calculations run in your browser. No data is stored or sent to any server.
How it works
- Enter your stats - age, gender, height (cm), and weight (kg).
- Select activity level - from sedentary to extra active. This determines the multiplier applied to your BMR.
- Choose your goal - lose weight (-500 cal), maintain, or gain weight (+500 cal).
- Read your results - BMR, TDEE, goal calories, and macro targets update instantly.
Formulas
Male: BMR = 10 × weight(kg) + 6.25 × height(cm) - 5 × age + 5
Female: BMR = 10 × weight(kg) + 6.25 × height(cm) - 5 × age - 161
TDEE = BMR × Activity Multiplier
Activity Multipliers: Sedentary 1.2 | Light 1.375 | Moderate 1.55 | Very Active 1.725 | Extra Active 1.9
Worked Examples
30-year-old male, 170 cm, 70 kg, lightly active
BMR = 10(70) + 6.25(170) - 5(30) + 5 = 700 + 1062.5 - 150 + 5 = 1,618 kcal.
TDEE = 1,618 × 1.375 = 2,224 kcal/day.
To lose 0.5 kg/week: 2,224 - 500 = 1,724 kcal/day.
Macros at 1,724 cal: Protein = 129g, Carbs = 172g, Fat = 57g.
Tips
BMI, BMR, TDEE - what they actually measure
Three numbers often confused; they answer different questions:
| Metric | Formula | What it tells you |
|---|---|---|
| BMI (Body Mass Index) | weight kg / height m^2 | Rough screen for under/normal/over weight. Bad for athletes. |
| BMR (Basal Metabolic Rate) | Mifflin-St Jeor equation | Calories your body burns AT REST in 24 hours |
| TDEE (Total Daily Energy Expenditure) | BMR x activity multiplier | Total calories burned per day, including activity |
| Body fat % | DEXA / calipers / bioimpedance | More accurate than BMI for athletes and very lean people |
WHO BMI categories
| Category | BMI range | Notes |
|---|---|---|
| Underweight | < 18.5 | Increased risk of malnutrition, osteoporosis |
| Normal | 18.5 - 24.9 | Lowest health risk for most adults |
| Overweight | 25.0 - 29.9 | Increased risk of cardiovascular disease, diabetes |
| Obese class I | 30.0 - 34.9 | High risk; lifestyle change recommended |
| Obese class II | 35.0 - 39.9 | Very high risk; clinical intervention often warranted |
| Obese class III | >= 40.0 | Extreme risk; bariatric options often discussed |
Asian-specific BMI cutoffs
South Asians have higher cardiovascular risk at lower BMI. India, Singapore, and many Asian countries use:
- Underweight: < 18.5
- Normal: 18.5 - 22.9
- Overweight: 23.0 - 27.4
- Obese: >= 27.5
Calorie math for weight change
The simplified energy balance:
- 1 kg of body fat = approximately 7,700 kcal
- 1 lb of body fat = approximately 3,500 kcal
To lose 0.5 kg / 1 lb per week, eat ~500 kcal/day below TDEE. To gain muscle, eat 200-500 kcal/day above TDEE with adequate protein (~1.6g per kg body weight per day) and resistance training.
Caveats:
- "Calories in vs out" is the right framework, but the body adapts - metabolism slows ~10-15% during sustained weight loss, so progress slows over months.
- Hormones (insulin, leptin, ghrelin, thyroid) modulate hunger and storage. Not all calories are equally easy to eat.
- Sleep and stress affect both intake and expenditure measurably.
Protein, fat, carbs - what's needed
| Macronutrient | Daily target | Energy density |
|---|---|---|
| Protein | 0.8 g/kg sedentary; 1.6-2.2 g/kg if exercising | 4 kcal/g |
| Fat | 20-35% of total calories; minimum ~0.5 g/kg | 9 kcal/g |
| Carbohydrate | Fills the rest; minimum 130 g/day for brain function | 4 kcal/g |
| Fiber | 25-38 g/day | ~2 kcal/g (variable) |
| Water | 30-40 ml/kg body weight | 0 kcal/g |
Frequently asked questions
How many calories should I eat per day?
It depends on your age, gender, height, weight, and activity level. A typical adult male needs 2,000-2,500 kcal/day to maintain weight; a typical adult female needs 1,600-2,000 kcal/day. Use the Mifflin-St Jeor equation for a personalized estimate.
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) = BMR × activity multiplier. TDEE is what you actually burn in a day including movement and exercise.
How many calories to lose 1 kg per week?
1 kg of body fat ≈ 7,700 calories. To lose 1 kg/week, you need a deficit of about 1,100 calories/day. A safer target is 0.5 kg/week (550 cal/day deficit), which is what this calculator uses by default.
What is the Mifflin-St Jeor equation?
It's the most accurate BMR formula for most adults, validated in a 2005 ADA review. For men: BMR = 10×weight(kg) + 6.25×height(cm) - 5×age + 5. For women: same but -161 instead of +5.
Is the 40/30/30 macro split right for everyone?
It's a reasonable default for general fitness. For weight loss, higher protein (35-40%) helps preserve muscle. For endurance athletes, higher carbs (50-60%) are better. Use our Macro Calculator for customized splits.
Is BMI accurate for me?
BMI is a population screening tool, not an individual diagnosis. It overestimates body fat in muscular athletes and underestimates it in people with low muscle mass. Body fat percentage (DEXA, calipers) is more accurate. Waist-to-height ratio under 0.5 is another useful single number.
How much weight can I safely lose per week?
0.5-1 kg (1-2 lb) per week is sustainable for most adults. Faster loss is possible but typically comes from water, glycogen, and muscle - not just fat. Crash diets also slow metabolism and rebound when normal eating resumes.
Are calorie calculators accurate?
BMR estimates are within ±10% of measured rates for most people. TDEE depends on self-reported activity, which is usually overestimated by 20-50%. Track actual weight change over 2-4 weeks and adjust intake to match.
Why does my weight fluctuate 2-3 kg in a single day?
Almost all daily fluctuation is water (sodium, carbohydrate storage as glycogen which holds 3-4x its weight in water) and digestive contents. Fat loss is on the order of 100-150g per day at most. Weigh weekly at the same time for trend, not daily.
Is fasting better than calorie restriction?
For weight loss, the two are equivalent if total calories are the same. Some people find fasting easier to comply with (skipping breakfast = automatic deficit). Others find it harder. The best diet is the one you can sustain.
How accurate is the Calorie Calculator (BMR & TDEE)?
It applies the standard formula. Accuracy is limited only by your input precision. For decisions with material consequences (taxes, medical, legal, structural), use the result as a starting point and verify with a qualified professional in the relevant field.
Is the Calorie Calculator (BMR & TDEE) free to use?
Yes. 100% free, no signup, no payment, no API key. The site is funded by display ads around the tool but not inside the calculation flow.
Are my inputs saved anywhere?
No. All inputs stay in your browser tab. Closing the tab discards them. The site uses Google Analytics for traffic measurement (anonymized) but the analytics never see what you type into the form.
Can I use the Calorie Calculator (BMR & TDEE) on my phone?
Yes. The tool is responsive and tested on iOS Safari, Android Chrome, and major desktop browsers. Touch targets meet Apple's 44pt and Google's 48dp minimum.
Does the Calorie Calculator (BMR & TDEE) work offline?
Yes. Once the page has loaded, it works without internet. The calculation runs in JavaScript on your device.
How do I report a bug or suggest improvement to the Calorie Calculator (BMR & TDEE)?
Email hi@3tej.com with the URL of this page and a description of what you saw vs expected. We typically respond within 72 hours.
Can I share results from the Calorie Calculator (BMR & TDEE)?
Take a screenshot or copy the output. The page doesn't generate shareable URLs for specific calculations - inputs stay in your browser only.
Why are the results different from another calorie calculator (bmr & tdee) tool?
Most likely: different formula assumptions, different default values, different rounding rules, or different applicable rates. Check the methodology if both tools document it. Both can be valid for different scenarios.