Daily Calorie Calculator (Mifflin-St Jeor Formula)
Estimate daily calories for weight loss, maintenance, or muscle gain using the Mifflin-St Jeor and Harris-Benedict formulas.
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Daily Calorie Calculator (Mifflin-St Jeor Formula) Formula
BMR = 10 × weight(kg) + 6.25 × height(cm) - 5 × age + s (s = +5 male, -161 female)
The Mifflin-St Jeor equation calculates Basal Metabolic Rate (BMR) — calories burned at rest. BMR is multiplied by an activity factor (1.2 sedentary to 1.9 extremely active) to get Total Daily Energy Expenditure (TDEE), which represents maintenance calories. Weight loss requires eating below TDEE, weight gain requires eating above TDEE.
Daily Calorie Calculator (Mifflin-St Jeor Formula) — Worked Examples
Example 1: Sedentary Adult Male — Maintenance Calories (TDEE)
Problem:A 42-year-old male, 5 ft 11 in (180.3 cm), 185 lbs (83.9 kg), sedentary office worker with no structured exercise. What are his maintenance calories?
Solution:Height = 5 ft 11 in = 180.3 cm\nWeight = 185 lbs = 83.9 kg\n\nBMR (Mifflin-St Jeor, male):\n= 10 x 83.9 + 6.25 x 180.3 - 5 x 42 + 5\n= 839 + 1,126.9 - 210 + 5\n= 1,761 cal/day\n\nTDEE (sedentary multiplier x 1.2):\n= 1,761 x 1.2 = 2,113 cal/day\n\nThis is his maintenance intake to hold current weight with minimal activity.
Result:BMR: 1,761 cal/day | TDEE (maintenance): 2,113 cal/day
Example 2: Active Young Female — Weight Loss Deficit
Problem:A 26-year-old female, 5 ft 5 in (165.1 cm), 155 lbs (70.3 kg), lightly active (walks daily, gym 2x/week). She wants to lose 1 lb per week. What deficit target should she use?
Solution:Height = 5 ft 5 in = 165.1 cm\nWeight = 155 lbs = 70.3 kg\n\nBMR (Mifflin-St Jeor, female):\n= 10 x 70.3 + 6.25 x 165.1 - 5 x 26 - 161\n= 703 + 1,031.9 - 130 - 161\n= 1,444 cal/day\n\nTDEE (light activity x 1.375):\n= 1,444 x 1.375 = 1,985 cal/day\n\nWeight loss target (-500 cal deficit = ~1 lb/week):\n= 1,985 - 500 = 1,485 cal/day\n\nMacros at 30/40/30 split on deficit:\nProtein = 1,485 x 0.30 / 4 = 111 g\nCarbs = 1,485 x 0.40 / 4 = 149 g\nFat = 1,485 x 0.30 / 9 = 50 g
Result:BMR: 1,444 | TDEE: 1,985 | Weight loss target: 1,485 cal/day | Macros: 111 g protein, 149 g carbs, 50 g fat
Example 3: Athletic Male — High Activity Performance Nutrition
Problem:A 24-year-old male, 6 ft 0 in (182.9 cm), 175 lbs (79.4 kg), trains 6 days per week (strength and conditioning). What are his calorie needs for performance and lean muscle gain?
Solution:Height = 6 ft 0 in = 182.9 cm\nWeight = 175 lbs = 79.4 kg\n\nBMR (Mifflin-St Jeor, male):\n= 10 x 79.4 + 6.25 x 182.9 - 5 x 24 + 5\n= 794 + 1,143.1 - 120 + 5\n= 1,822 cal/day\n\nTDEE (very active x 1.725):\n= 1,822 x 1.725 = 3,143 cal/day\n\nLean gain target (+250 cal surplus):\n= 3,143 + 250 = 3,393 cal/day\n\nMacros for performance (35/40/25 split):\nProtein = 3,393 x 0.35 / 4 = 297 g\nCarbs = 3,393 x 0.40 / 4 = 339 g\nFat = 3,393 x 0.25 / 9 = 94 g
Result:BMR: 1,822 | TDEE: 3,143 | Lean gain target: 3,393 cal/day | Macros: 297 g protein, 339 g carbs, 94 g fat
Daily Calorie Calculator (Mifflin-St Jeor Formula) — Frequently Asked Questions
How does the calorie calculator estimate daily needs?
Daily Calorie Calculator (Mifflin-St Jeor Formula) uses the Mifflin-St Jeor equation to estimate basal metabolic rate and then applies an activity multiplier to estimate total daily energy expenditure. That gives a practical maintenance-calorie estimate.
Why can calorie needs change over time?
Body weight, activity level, muscle mass, age, and day-to-day movement all influence energy needs. A calculator gives a starting estimate, but real-world tracking is what fine-tunes the target.
How accurate are calorie calculators?
They are estimates, not exact measurements. For many people they are close enough to begin, but actual maintenance calories should be confirmed by watching weight and intake over a few weeks.
How much water should I drink daily?
Daily water needs vary significantly by body size, activity level, climate, and diet. The commonly cited 8×8 rule (eight 8-oz glasses = 64 oz) is a rough average. A more personalized approach is to drink about half your body weight in ounces — a 160 lb person targets roughly 80 oz (2.4 liters). The National Academies recommend approximately 3.7 liters total daily water for men and 2.7 liters for women, including water from food (which contributes about 20%). Exercise, heat, altitude, and illness all increase requirements substantially — strenuous exercise in heat can require an additional 1-2 liters per hour. The simplest real-time indicator is urine color: pale straw yellow indicates good hydration; dark yellow or amber signals dehydration.