Your personalized daily calorie target based on the Mifflin-St Jeor equation — the most accurate clinically-validated formula. Factors in your age, body type, fitness level, and goals.
This calculator uses two clinically-validated equations depending on your inputs:
Mifflin-St Jeor Equation (Default)
Developed in 1990 and considered the gold standard by the American Dietetic Association. Accurate to within ±10% for most adults.
The Formula
Men: BMR = (10 × weight in kg) + (6.25 × height in cm) – (5 × age) + 5 Women: BMR = (10 × weight in kg) + (6.25 × height in cm) – (5 × age) – 161
Katch-McArdle Formula (When Body Fat % Is Provided)
Uses lean body mass (LBM) instead of total weight. More accurate for athletic individuals who know their body fat percentage.
The Formula
BMR = 370 + (21.6 × lean body mass in kg) Lean body mass = weight × (1 – body fat % / 100)
From BMR to TDEE
Your BMR is then multiplied by an activity factor to get your Total Daily Energy Expenditure (TDEE) — the total calories you burn per day including all movement and exercise:
Activity Level
Multiplier
Description
Sedentary
× 1.2
Desk job, minimal walking, no exercise
Lightly Active
× 1.375
Light exercise 1-3 days/week or active commute
Moderately Active
× 1.55
Moderate exercise 3-5 days/week
Very Active
× 1.725
Hard exercise 6-7 days/week
Extremely Active
× 1.9
Professional athlete or very physical job + training
Body Type Adjustment
Research shows individual metabolic rates can vary by 5-10% even among people with the same height, weight, and age. Body type is a practical proxy for this variation:
🦴
Ectomorph (+5% TDEE)
Naturally thin with fast metabolism. Tends to burn more calories at rest. Often has long limbs, narrow shoulders, and difficulty gaining weight.
💪
Mesomorph (No adjustment)
Naturally muscular and responsive to training. Gains and loses weight relatively easily. The baseline for most calorie formulas.
🐻
Endomorph (–5% TDEE)
Naturally broader build with slower metabolism. Tends to store fat more easily. May need slightly fewer calories than predicted.
Calorie Needs by Body Type & Goal
Here's a reference table showing estimated daily calorie needs for common profiles. These assume moderate activity (3-5 days/week exercise):
Profile
Maintain
Lose Fat
Build Muscle
Woman, 25, 5'4", 130 lbs
1,900
1,400–1,650
2,100–2,200
Woman, 35, 5'6", 155 lbs
2,100
1,600–1,850
2,300–2,400
Woman, 45, 5'5", 145 lbs
1,950
1,450–1,700
2,150–2,250
Man, 25, 5'10", 170 lbs
2,600
2,100–2,350
2,800–2,950
Man, 35, 6'0", 190 lbs
2,750
2,250–2,500
2,950–3,100
Man, 45, 5'9", 185 lbs
2,550
2,050–2,300
2,750–2,900
Man, 25, 6'2", 210 lbs (athlete)
3,200
2,700–2,950
3,400–3,550
Setting the Right Calorie Target by Goal
For Fat Loss
A moderate deficit of 300–500 calories below TDEE is the sweet spot for most people. This produces steady fat loss of 0.5–1 lb per week while preserving muscle mass. Larger deficits (750+) can work short-term but risk muscle loss, metabolic adaptation, and are harder to sustain.
✅ Best practice for fat loss
Set deficit at 15–25% of TDEE. Keep protein high (0.8–1g per lb of body weight). Strength train 3–4x/week to preserve muscle. Recalculate every 10–15 lbs lost as your TDEE drops with your weight.
For Muscle Gain
You need a calorie surplus to build muscle — but not a massive one. A surplus of 200–350 calories above TDEE maximizes muscle growth while minimizing fat gain. Beginners can gain muscle faster (1–2 lbs/month) than advanced lifters (0.25–0.5 lbs/month).
✅ Best practice for muscle gain
Surplus of 10–15% of TDEE. Protein: 0.8–1g per lb of body weight. Progressive overload in training is more important than the surplus size. Beginners should use a smaller surplus — you can build muscle on maintenance or even a slight deficit ("newbie gains").
For Maintenance
Eating at TDEE keeps your weight stable. This is ideal for body recomposition (losing fat while building muscle simultaneously), which is possible for beginners, overweight individuals, and people returning to training after a break.
7 Tips for Using This Calculator Accurately
1️⃣
Be Honest About Activity Level
The #1 mistake is overestimating activity. If you train 3x/week but sit at a desk all day, you're "Lightly Active" — not "Very Active." Only count intentional exercise.
2️⃣
Track for 2–3 Weeks Before Adjusting
Treat the calculator result as a starting point. Weigh yourself daily (same time, morning, after bathroom) and average weekly. Adjust by 100–200 cal if your weight isn't moving as expected.
3️⃣
Recalculate Every 10–15 lbs
Your TDEE drops as you lose weight and increases as you gain. A person who was 200 lbs and is now 170 lbs needs ~200 fewer calories per day just from the weight change alone.
4️⃣
Don't Go Below Minimum Thresholds
Women should not eat below 1,200 cal/day and men below 1,500 cal/day without medical supervision. Below these thresholds, it's very difficult to get adequate nutrition.
5️⃣
Protein Is the Priority Macro
Whether losing or gaining, keep protein at 0.7–1g per lb of body weight. Protein preserves muscle during a cut, builds muscle during a bulk, and is the most satiating macronutrient.
6️⃣
Account for NEAT
Non-Exercise Activity Thermogenesis (NEAT) — fidgeting, walking, standing — accounts for 15-30% of daily calorie burn for most people. This varies hugely between individuals and is why some people are "naturally thin."
7️⃣
Body Fat % Improves Accuracy
If you know your body fat percentage (from a DEXA scan, calipers, or even a visual estimate), enter it above. The Katch-McArdle formula it enables is more accurate for lean or muscular individuals.
Frequently Asked Questions
How many calories should I eat per day? ▼
It depends on your individual stats. The average adult needs 1,600–2,400 cal/day (women) or 2,000–3,000 cal/day (men) to maintain weight. For weight loss, subtract 300–500 cal from your TDEE. For muscle gain, add 200–350 cal. The calculator above uses the Mifflin-St Jeor equation — the most accurate clinically-validated formula — to give you a personalized number.
What's the difference between BMR and TDEE? ▼
BMR (Basal Metabolic Rate) is the calories your body burns at complete rest — just to keep your heart beating and lungs breathing. It's typically 60-70% of total daily burn. TDEE (Total Daily Energy Expenditure) is BMR plus all calories from activity, exercise, and digesting food. Always base your calorie intake on TDEE, not BMR. Eating at BMR would leave you in a deficit since you burn additional calories through daily movement.
How much of a calorie deficit is safe? ▼
A deficit of 300–500 cal/day is considered safe and sustainable, producing ~0.5–1 lb of fat loss per week. Deficits larger than 35% of your TDEE are flagged by nutritionists as potentially harmful — they can cause muscle loss, metabolic slowdown, nutrient deficiencies, and hormonal disruption. Never go below 1,200 cal/day (women) or 1,500 cal/day (men) without medical supervision.
Does body type really affect metabolism? ▼
Yes, but modestly. Research shows metabolic rates can vary 5–10% between individuals of the same height, weight, and age. "Body type" (ectomorph/mesomorph/endomorph) is a simplified framework for this natural variation. More importantly, body composition matters — muscle tissue burns ~6 cal/lb/day at rest vs. ~2 cal/lb/day for fat. So someone with more muscle mass at the same weight burns more calories. The calculator applies a ±5% adjustment based on body type selection.
How accurate is this calculator? ▼
The Mifflin-St Jeor equation is accurate to within ±10% for most people, based on clinical studies comparing it to indirect calorimetry (the gold standard for measuring metabolism). If you enter your body fat percentage, the calculator switches to the Katch-McArdle formula, which can be more accurate for lean or athletic individuals. Either way, treat the result as a starting point and adjust based on your actual results over 2–3 weeks.
Should I eat back the calories I burn exercising? ▼
No — your activity level selection already factors in exercise calories. The activity multiplier accounts for your typical weekly exercise pattern. If you eat back exercise calories on top of that, you'll double-count and likely overeat. The exception: if you have an unusually intense workout (e.g., a 3-hour hike) that's far above your normal level, you may want to eat an extra 200–300 cal that day.
Data Sources: Mifflin MD, St Jeor ST, et al. "A new predictive equation for resting energy expenditure in healthy individuals." American Journal of Clinical Nutrition, 1990. · Frankenfield D, et al. "Comparison of predictive equations for resting metabolic rate." Journal of the American Dietetic Association, 2005. · Katch-McArdle Formula via McArdle WD, Katch FI, Katch VL. "Exercise Physiology," 2001. · Activity factors from WHO/FAO/UNU Report on Human Energy Requirements, 2004.
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