Calorie Calculator

Q: How do I calculate my daily calorie needs?

Use the Mifflin-St Jeor equation. For men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5. For women: subtract 161 instead of adding 5. Multiply BMR by an activity factor (1.2 sedentary to 1.9 very active) to get your TDEE — total daily energy expenditure.

Q: How many calories should I eat to lose weight?

A 500-calorie-per-day deficit below your TDEE produces about 1 pound of weight loss per week. A 1,000-calorie deficit targets 2 pounds per week but is harder to sustain. Avoid going below 1,200 calories for women or 1,500 for men without medical supervision.

Q: What's the difference between BMR and TDEE?

BMR (basal metabolic rate) is what you'd burn at complete rest — basic functions like breathing, circulation, and body temperature. TDEE (total daily energy expenditure) is BMR multiplied by your activity level, and it's the number you actually need to match or undershoot to maintain or lose weight.

Q: Why am I not losing weight on my calculated deficit?

Usually because actual intake is higher than estimated (most people underreport calories by 20–40%), or actual activity is lower than the multiplier assumes. Track for 2 weeks with a food scale and adjust.

Calculate your daily calorie needs using the Mifflin-St Jeor equation — the formula most nutritionists recommend over the older Harris-Benedict version. Shows your BMR (resting calories), TDEE (total daily burn), and deficit/surplus targets for weight loss or gain.

Quick answer

BMR (men) = 10 × kg + 6.25 × cm − 5 × age + 5. TDEE = BMR × activity factor (1.2–1.9). For weight loss, eat 500 cal below TDEE for ~1 lb/week loss.

Calorie Calculator (Mifflin-St Jeor)

Age

Gender

Height (inches)

Weight (lbs)

Activity Level

How the calorie calculator works

The Mifflin-St Jeor equation (1990) calculates your basal metabolic rate — the calories your body burns at complete rest for basic life functions like breathing, circulation, and temperature regulation. For men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5. For women: the same formula but subtract 161 at the end instead of adding 5. The American Dietetic Association recommends Mifflin-St Jeor over the older Harris-Benedict equation because it's more accurate for modern populations.

To get your TDEE (total daily energy expenditure), multiply BMR by an activity factor: 1.2 for sedentary (desk job, no exercise), 1.375 for lightly active (1–3 workouts per week), 1.55 for moderate (3–5 workouts), 1.725 for active (6–7 workouts), and 1.9 for very active (physically demanding job + daily training). Most people sit between 1.2 and 1.55; few actually earn 1.725 or higher without careful tracking.

When to use it

Use this calculator as your starting point for any weight goal — loss, maintenance, or gain. A pound of body fat stores about 3,500 calories, so a daily deficit of 500 calories produces roughly 1 pound per week of fat loss, while a 1,000-calorie deficit targets 2 pounds per week. The calculator shows both a 500-cal deficit (loss) and 500-cal surplus (gain) as default targets.

Track your weight weekly (not daily — daily fluctuations are noise) and your intake carefully for 2 weeks. If the scale moves as predicted, your estimate is accurate. If it's slower or faster than expected, adjust your intake by ~10% in either direction. After 4–6 weeks, reassess — your TDEE drops as you lose weight, so targets need periodic updates.

Common mistakes

Overestimating activity level. Most desk workers who do 3–4 workouts a week are "lightly active" (1.375), not "moderately active" (1.55). Start lower.
Underreporting calories. Studies show most people underreport intake by 20–40%. Weigh food on a scale for 2 weeks to calibrate your eye.
Going too aggressive. Deficits over 1,000 cal/day are hard to sustain and often backfire via binges. A 500-cal deficit is both effective and livable.
Ignoring protein. Cutting calories without adequate protein (0.7–1 g per lb bodyweight) loses muscle along with fat. Protein is non-negotiable on a deficit.
Treating calories as the only metric. A 1,500-calorie day of vegetables, lean protein, and whole grains is very different from 1,500 calories of donuts — even if the scale agrees.

Frequently asked questions

How do I calculate my daily calorie needs?

Use the Mifflin-St Jeor equation. Men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5. Women: subtract 161 instead. Multiply by an activity factor (1.2 to 1.9) for TDEE.

How many calories should I eat to lose weight?

A 500-calorie daily deficit produces about 1 pound of loss per week. A 1,000-cal deficit targets 2 pounds but is harder to sustain. Don't go below 1,200 (women) or 1,500 (men) without medical supervision.

What's the difference between BMR and TDEE?

BMR is calories burned at complete rest. TDEE is BMR times your activity level — the number you need to match or undershoot to maintain or lose weight.

Why am I not losing weight on my calculated deficit?

Usually because actual intake is higher than estimated, or activity is lower than assumed. Track with a food scale for 2 weeks and adjust.

Do calories in vs calories out really work?

Yes — the first law of thermodynamics applies to humans. But "calories in" includes hidden sources (cooking oils, sauces, drinks) and "calories out" shifts with weight loss, so the math is harder than it sounds.