Calculate Total Daily Energy Expenditure using Mifflin-St Jeor.
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Daily protein, carb, and fat targets by calorie goal.
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Body Mass Index from height and weight.
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Recommended daily water intake by weight and exercise.
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Estimate one-rep max from submaximal lifts.
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Body fat percentage using the U.S. Navy method.
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Track caffeine half-life — see remaining mg each hour.
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Best time to fall asleep based on 90-minute sleep cycles.
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Daily protein target by weight and fitness goal.
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Running pace, speed, and estimated 5K time.
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Whether you're starting a fitness journey, optimizing your nutrition, or curious about your body metrics, these calculators provide science-backed estimates using established formulas from sports science and nutrition research.
Your Total Daily Energy Expenditure (TDEE) is the foundation of any nutrition plan. Our calculator uses the Mifflin-St Jeor equation — considered the most accurate BMR formula by the Academy of Nutrition and Dietetics. To lose weight, eat below your TDEE (typically 500 calories less for 1 pound per week of fat loss). To gain muscle, eat above it (typically 300 calories more). The macro calculator splits your calorie target into protein, carbohydrates, and fat based on your goal.
BMI provides a quick screening tool based on height and weight, though it doesn't distinguish between muscle and fat. The body fat calculator uses the U.S. Navy method, estimating body fat percentage from waist, neck, and height measurements. This method has been validated in multiple studies and requires no special equipment.
The one-rep max calculator estimates your maximum lift using the Epley formula, then provides training percentages for different rep ranges. The running pace calculator converts between pace per mile, pace per kilometer, and speed. The caffeine tracker shows how caffeine metabolizes over time with a half-life of approximately 5 hours, helping you time your last coffee. The sleep cycle calculator finds optimal bedtimes based on 90-minute sleep cycles.
Your Total Daily Energy Expenditure (TDEE) is the total number of calories your body burns in a day. It's composed of three parts: your Basal Metabolic Rate (BMR) — calories burned just staying alive (breathing, circulating blood, maintaining body temperature), the Thermic Effect of Food (TEF) — energy used to digest food, and your activity level — everything from walking to intense exercise.
The Mifflin-St Jeor equation, which our calculator uses, is considered the most accurate BMR formula according to a 2005 study published in the Journal of the American Dietetic Association. It accounts for sex, age, height, and weight. To lose fat, eat 300-500 calories below your TDEE. To gain muscle, eat 200-300 above. Going more extreme than this typically leads to muscle loss or excessive fat gain.
The RDA for protein (0.36g per pound) is the minimum to prevent deficiency — not the optimal amount for health or fitness. Research consistently shows that 0.7-1.0g per pound of body weight is ideal for maintaining muscle mass, and up to 1.2g per pound for those actively building muscle through resistance training.
Protein also has the highest thermic effect of any macronutrient — your body burns about 20-30% of protein calories just digesting it, compared to 5-10% for carbs and 0-3% for fat. This means a high-protein diet effectively increases your TDEE slightly, making it easier to maintain a caloric deficit.
Sleep occurs in 90-minute cycles, each containing stages of light sleep, deep sleep, and REM (dream) sleep. Waking up mid-cycle — especially during deep sleep — causes grogginess and fatigue, even if you slept 8 hours. Waking at the end of a cycle feels refreshing even with less total sleep.
Our sleep calculator works backward from your wake time in 90-minute intervals, adding 15 minutes to fall asleep. If you need to wake at 7:00 AM, ideal bedtimes are 9:15 PM (6 cycles, 9h), 10:45 PM (5 cycles, 7.5h), or 12:15 AM (4 cycles, 6h). Most adults need 5-6 cycles per night for optimal cognitive function.
BMI (Body Mass Index) is a simple height-to-weight ratio that doesn't account for muscle mass, bone density, or fat distribution. A muscular athlete and an overweight sedentary person can have the same BMI. Body fat percentage is a more accurate measure of health — for men, 10-20% is considered healthy, and for women, 18-28%.
The U.S. Navy method estimates body fat using circumference measurements (waist, neck, and hips for women). While not as accurate as DEXA scans or hydrostatic weighing, it's free, requires only a tape measure, and is accurate within 3-4% for most people.