How accurate is this calorie calculator?

We use the Mifflin–St Jeor equation by default, which research shows predicts resting metabolic rate within ~10% for most healthy adults. Real-world calorie needs vary with NEAT (fidgeting, movement), sleep, stress, and medical conditions — treat the result as a starting point, then adjust based on weekly weight trends.

What is BMR and how is it different from TDEE?

BMR (Basal Metabolic Rate) is the energy your body burns at complete rest just to stay alive — breathing, heartbeat, organ function. TDEE (Total Daily Energy Expenditure) is BMR multiplied by an activity factor that accounts for movement, exercise, and digestion. TDEE is the number you eat at to maintain weight.

How many calories should I eat to lose 1 lb per week?

One pound of body fat is about 3,500 kcal, so a 500 kcal/day deficit yields roughly 1 lb (0.45 kg) of weight loss per week. For 2 lb/week you'd need a 1,000 kcal/day deficit — usually too aggressive and hard to sustain. Most people do best at 0.5–1% of bodyweight loss per week.

Should I ever eat below my BMR?

Generally no. Eating below BMR for extended periods can slow metabolic adaptation, increase muscle loss, and make the deficit hard to sustain. If your goal calories drop below BMR, increase activity, take a diet break, or accept a slower rate of loss.

Which formula is most accurate — Mifflin–St Jeor, Harris–Benedict, or Katch–McArdle?

Mifflin–St Jeor (1990) is the most accurate for the general population and is the default here. Revised Harris–Benedict (1984) is similar but slightly overestimates for many people. Katch–McArdle is more accurate if you know your body fat percentage, because it works from lean body mass.

How often should I recalculate my calories?

Recalculate every 4–8 weeks, or any time your weight changes by ~5 kg (10 lb), your activity level shifts, or weight loss/gain stalls for 2–3 weeks. As you lose weight your BMR drops, so the same calorie target stops producing the same deficit.

Do macronutrient ratios matter more than total calories?

Total calories drive weight change. Macros (protein, carbs, fat) influence body composition, satiety, and performance. A high-protein intake (1.6–2.2 g/kg) is the most evidence-backed lever for preserving muscle in a deficit and supporting hypertrophy in a surplus.

What activity level should I pick?

Sedentary = desk job, little movement. Light = walking + light exercise 1–3×/week. Moderate = exercise 3–5×/week. Active = hard exercise 6–7×/week. Very Active = physical job plus daily training. People consistently overestimate — when in doubt, pick one level lower.

Why are my calorie needs different from a friend's at the same weight?

Two people of identical weight can have very different needs: more lean mass burns more at rest, age lowers BMR ~1–2% per decade, sex (men typically need more), height, and daily activity all matter. The formula captures the biggest drivers but not all individual variation.

Are 'calories in vs calories out' still valid in 2026?

Yes — the first law of thermodynamics still applies. What's evolved is understanding that both sides are dynamic: hormones, sleep, stress, and food choices influence hunger and energy expenditure. The equation is real; the inputs are harder to measure than people assume.

Is this calculator suitable for children or pregnant women?

No. Standard BMR equations are validated for non-pregnant, non-lactating adults aged 18+. Children, pregnant or breastfeeding women, and people with metabolic conditions should consult a registered dietitian or physician for individualized needs.

Is my data stored anywhere?

No. All calculations run entirely in your browser. Your age, weight, height, and other inputs are never sent to a server, saved, or tracked — the tool works offline once the page has loaded.

Calorie Calculator — Daily Calorie Needs (BMR & TDEE)

How to Use This Calorie Calculator

Four quick steps. Every result shows BMR, TDEE, and a macro breakdown so you can verify the numbers at a glance.

Enter your details

Age, sex, height, and weight in metric or imperial.

Pick activity

Honest weekly activity level — most people overestimate.

Choose a goal

Maintain, lose, or gain — adjusts your daily target.

Read the result

BMR, TDEE, goal calories, and a macro split.

What Is BMR (Basal Metabolic Rate)?

The minimum energy your body needs to keep you alive at rest.

BMR is the calories burned for involuntary functions: heartbeat, breathing, brain activity, cell repair, and organ function. It typically accounts for 60–75% of your total daily energy expenditure. BMR scales with lean body mass, falls slowly with age (~1–2% per decade after 20), and is broadly higher in men than women at the same weight because of higher lean mass.

What Is TDEE (Total Daily Energy Expenditure)?

BMR plus everything else you burn in a day. This is your maintenance calorie target.

TDEE = BMR × activity multiplier. The multiplier captures NEAT (non-exercise activity thermogenesis), exercise, and the thermic effect of food (~10% of intake).

Activity level	Description	Multiplier
Sedentary	Little or no exercise	1.2
Light	1–3 days/week	1.375
Moderate	3–5 days/week	1.55
Active	6–7 days/week	1.725
Very Active	Hard daily + physical job	1.9

Formulas We Use

Hover any formula for a plain-English explanation.

Mifflin–St Jeor (default)

The most accurate equation for the general adult population, published in 1990. Used by default in this calculator.

Male

10·kg + 6.25·cm − 5·age + 5

Female

10·kg + 6.25·cm − 5·age − 161

Revised Harris–Benedict (1984)

The classic equation, revised by Roza and Shizgal. Slightly overestimates BMR for most modern populations versus Mifflin.

Katch–McArdle

Uses lean body mass instead of total weight, so it's the most accurate option if you know your body fat percentage (DEXA, calipers, or a reliable estimate).

BMR = 370 + 21.6 × lean body mass (kg)

Calories for Loss, Maintenance, and Gain

A pound of body fat ≈ 3,500 kcal. A kilogram ≈ 7,700 kcal. Adjust your daily intake from TDEE accordingly.

Lose weight

Eat 250–750 kcal below TDEE. Cap deficits at ~20% of TDEE to preserve muscle and adherence.

Maintain

Eat at TDEE. Expect ±1–2 kg of normal water-weight fluctuation week to week.

Gain muscle

Eat 200–500 kcal above TDEE with resistance training. Larger surpluses add more fat, not more muscle.

Macronutrients Explained

Macros are the calorie-providing nutrients. Each gram carries a fixed energy value.

Protein

4 kcal/g

Carbohydrate

4 kcal/g

Fat

9 kcal/g

Worked Example

A 30-year-old woman, 165 cm, 65 kg, moderately active, wanting mild fat loss.

BMR (Mifflin): 10×65 + 6.25×165 − 5×30 − 161 = 1,370 kcal
TDEE: 1,370 × 1.55 (moderate) = 2,124 kcal
Goal calories: 2,124 − 275 (mild loss) ≈ 1,850 kcal/day
Macros (balanced 30/40/30): 139 g protein · 185 g carbs · 62 g fat
Expected result: ~0.25 kg/week loss for the first 4–6 weeks

Common Use Cases

Where a calorie target is the right starting point.

Fat loss / cutting phases

Bulking / muscle gain

Body recomposition

Endurance training fueling

Post-injury / sedentary periods

Tracking weekly trends

Tips for Accuracy

Weigh yourself at the same time of day (typically morning, post-bathroom).
Use a 7-day rolling weight average — daily numbers are noise.
Measure food by weight when possible; volume measurements drift 20–40%.
Recalculate every 4–8 weeks or after ~5 kg of weight change.
If progress stalls 2–3 weeks, drop ~5% of calories or add ~1,000 steps/day.

Limitations & Disclaimer

This calculator provides estimates for healthy non-pregnant adults. It is not medical advice. People with diabetes, thyroid conditions, eating-disorder history, who are pregnant or breastfeeding, or under 18 should consult a registered dietitian or physician before changing their intake.

Frequently Asked Questions

Quick answers to the questions people ask most about calorie needs. Every answer here is mirrored in the page's FAQPage structured data for search engines.

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Age Calculator

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Percentage Calculator

Find a percent of a number, ratio to percent, or percentage change.

How to Use This Calorie Calculator

What Is BMR (Basal Metabolic Rate)?

What Is TDEE (Total Daily Energy Expenditure)?

Formulas We Use

Mifflin–St Jeor (default)

Revised Harris–Benedict (1984)

Katch–McArdle

Calories for Loss, Maintenance, and Gain

Macronutrients Explained

Worked Example

Common Use Cases

Tips for Accuracy

Limitations & Disclaimer

Frequently Asked Questions

How accurate is this calorie calculator?

How accurate is this calorie calculator?

What is BMR and how is it different from TDEE?

What is BMR and how is it different from TDEE?

How many calories should I eat to lose 1 lb per week?

How many calories should I eat to lose 1 lb per week?

Should I ever eat below my BMR?

Should I ever eat below my BMR?

Which formula is most accurate — Mifflin–St Jeor, Harris–Benedict, or Katch–McArdle?

Which formula is most accurate — Mifflin–St Jeor, Harris–Benedict, or Katch–McArdle?

How often should I recalculate my calories?

How often should I recalculate my calories?

Do macronutrient ratios matter more than total calories?

Do macronutrient ratios matter more than total calories?

What activity level should I pick?

What activity level should I pick?

Why are my calorie needs different from a friend's at the same weight?

Why are my calorie needs different from a friend's at the same weight?

Are 'calories in vs calories out' still valid in 2026?

Are 'calories in vs calories out' still valid in 2026?

Is this calculator suitable for children or pregnant women?

Is this calculator suitable for children or pregnant women?

Is my data stored anywhere?

Is my data stored anywhere?

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