Calorie Calculator
Estimate your Basal Metabolic Rate (BMR) and Total Daily Energy Expenditure (TDEE). Select your goal below to calculate an evidence-based daily calorie intake for fat loss, maintenance, or lean muscle gain, complete with macronutrient targets and clinical safety floors.
Calculate your daily calorie targets
Enter your body measurements, weekly activity level, and training goal. Results update instantly as you change any field.
What is maintenance calories and how energy expenditure works
Your maintenance calories—known in exercise science as Total Daily Energy Expenditure (TDEE)—is the total number of calories your body burns in a 24-hour period. When your average daily calorie intake equals your TDEE, you are in energy balance, and your body weight remains stable over time.
Total daily expenditure is comprised of four distinct components:
- Basal Metabolic Rate (BMR, ~60–70%): The energy required to sustain vital physiological functions at complete rest (cellular respiration, organ function, circulation, and temperature regulation).
- Thermic Effect of Food (TEF, ~8–12%): The metabolic cost of digesting, absorbing, and metabolizing nutrients. Dietary protein has the highest thermic effect (~20–30% of energy consumed), while carbohydrates (~5–10%) and dietary fats (~0–3%) require significantly less metabolic energy to process.
- Exercise Activity Thermogenesis (EAT, ~5–15%): Planned physical workouts, resistance training sessions, and cardiovascular exercise.
- Non-Exercise Activity Thermogenesis (NEAT, ~15–30%): All spontaneous physical movement that is not purposeful exercise: walking to work, taking stairs, fidgeting, posture maintenance, and carrying groceries. NEAT is the most variable component between individuals and often drops involuntarily during prolonged dieting.
Validated clinical BMR formulas compared
Rather than using rough guesses, this tool lets you compare three scientifically published predictive equations:
- Mifflin-St Jeor (1990): Developed from indirect calorimetry measurements of 498 healthy individuals. Systematic reviews published in the Journal of the American Dietetic Association consistently identify Mifflin-St Jeor as the most reliable equation for healthy non-obese and obese adults, with predictions falling within ±10% of measured resting metabolic rate in over 70% of subjects. [1]
Men: BMR = (10 × weight_kg) + (6.25 × height_cm) - (5 × age_years) + 5Women: BMR = (10 × weight_kg) + (6.25 × height_cm) - (5 × age_years) - 161 - Revised Harris-Benedict (Roza & Shizgal 1984): An updated regression of the classic 1919 Harris-Benedict equation based on body cell mass measurements. Tends to predict slightly higher metabolic rates in active young males compared to Mifflin-St Jeor. [2]
Men: BMR = 88.362 + (13.397 × weight_kg) + (4.799 × height_cm) - (5.677 × age_years)Women: BMR = 447.593 + (9.247 × weight_kg) + (3.098 × height_cm) - (4.330 × age_years) - Katch-McArdle (1988): Unlike formulas based on total weight, Katch-McArdle derives resting expenditure strictly from Fat-Free Mass (FFM). This makes it particularly accurate for lean bodybuilders and strength athletes who carry significantly more muscular tissue than the general population. [3]
Lean Mass (kg) = Total Weight (kg) × (1 - (Body Fat % / 100))BMR = 370 + (21.6 × Lean Mass_kg)
Step-by-step worked example: 80 kg active lifter
To see how the numbers connect from raw metrics to a daily meal target, consider a 30-year-old male lifter weighing 80 kg (176.4 lb) at 180 cm height (5 ft 11 in) who trains 4 days per week (Moderately Active, 1.55 multiplier) seeking sustainable fat loss.
- Step 1: Calculate BMR with Mifflin-St Jeor:
BMR = (10 × 80) + (6.25 × 180) - (5 × 30) + 5BMR = 800 + 1,125 - 150 + 5 = 1,780 kcal/day - Step 2: Multiply by Activity Level to find TDEE:
TDEE = 1,780 kcal × 1.55 = 2,759 kcal/day(Maintenance calories) - Step 3: Apply the Calorie Deficit:
For standard fat loss at ~0.5 kg (1.0 lb) per week, subtract 500 kcal:Target = 2,759 - 500 = 2,259 kcal/day - Step 4: Distribute Macronutrients:
- Protein: 2.0 g per kg of bodyweight =
80 × 2.0 = 160 g(160 × 4 = 640 kcal, 28% of intake). High protein protects skeletal muscle mass from breakdown during a calorie deficit (Morton et al. 2018). - Dietary Fat: 25% of daily energy intake =
2,259 × 0.25 = 565 kcal. Dividing by 9 kcal per gram yields63 g of fatto sustain testosterone synthesis and hormone production. - Carbohydrates: Remaining energy =
2,259 - 640 - 565 = 1,054 kcal. Dividing by 4 kcal per gram yields264 g of carbohydratesto fuel resistance training intensity and glycogen recovery.
- Protein: 2.0 g per kg of bodyweight =
How to calculate a calorie deficit and weight loss timeline
A calorie deficit occurs when you consume fewer calories than your body expends, forcing it to mobilize stored adipose tissue and glycogen for energy. While historical fitness folklore relies on Wishnofsky’s 1858 Rule—which asserts that burning 3,500 kcal equals exactly one pound of fat loss—modern metabolic research demonstrates that weight loss is dynamic rather than linear.
In a landmark paper published in The Lancet, Dr. Kevin Hall and colleagues from the National Institutes of Health (NIH) showed that as body mass decreases, three physiological adaptations occur simultaneously: [4]
- Reduced BMR: A lighter body burns fewer calories at rest because there is less tissue to maintain.
- Lower Work Cost: Moving a lighter body across daily tasks burns fewer calories.
- Adaptive Thermogenesis: The endocrine system downregulates thyroid hormones and increases hunger hormones (ghrelin) to conserve energy.
Consequently, an initial 500 kcal deficit produces about 1 lb of fat loss per week during the first few weeks, but gradual adaptation slows progress toward a plateau over 6 to 12 months unless physical activity increases or calorie intake is recalibrated.
For optimal results, aim for a deficit that targets 0.5% to 1.0% of your body weight lost per week. For an 80 kg individual, that represents 0.4 kg to 0.8 kg per week. Steeper deficits risk elevated muscle loss, impaired athletic recovery, and diet fatigue.
How many calories should you eat a day?
Reference ranges for daily calorie intake depend heavily on your sex, body mass, and activity habits. Below is a baseline reference table for typical adult body weights at moderate activity (1.55 activity factor):
| Body Weight | Sex | Maintenance (TDEE) | Fat Loss (−500 kcal) | Muscle Gain (+300 kcal) |
|---|---|---|---|---|
| 55 kg / 121 lb | Female | ~1,900 kcal/day | ~1,400 kcal/day | ~2,200 kcal/day |
| 65 kg / 143 lb | Female | ~2,100 kcal/day | ~1,600 kcal/day | ~2,400 kcal/day |
| 70 kg / 154 lb | Male | ~2,500 kcal/day | ~2,000 kcal/day | ~2,800 kcal/day |
| 80 kg / 176 lb | Male | ~2,750 kcal/day | ~2,250 kcal/day | ~3,050 kcal/day |
| 90 kg / 198 lb | Male | ~2,980 kcal/day | ~2,480 kcal/day | ~3,280 kcal/day |
| 100 kg / 220 lb | Male | ~3,200 kcal/day | ~2,700 kcal/day | ~3,500 kcal/day |
The biological minimum floors: 1,200 kcal and 1,500 kcal
Major clinical bodies, including the American College of Sports Medicine (ACSM) and the National Institutes of Health, strongly recommend avoiding unsupervised diets below 1,200 kcal/day for women and 1,500 kcal/day for men. [5]
Diets below these thresholds rarely provide adequate essential micronutrients (iron, zinc, B-vitamins, calcium), impair immune function, accelerate bone density reduction, and cause severe loss of functional muscle mass. If your calculated 500 kcal deficit would drop your intake below these floors, increase your daily step count and cardiovascular activity rather than restricting food further.
Real-world limitations of calorie calculation
While equations provide an indispensable baseline, empirical real-world tracking requires understanding three major sources of variance:
- Self-reporting and measurement error: Landmark research published in the New England Journal of Medicine by Lichtman et al. demonstrated that diet subjects under-report actual calorie intake by an average of 47% while over-reporting physical activity by 51%. Using a digital kitchen food scale rather than visual estimation resolves the vast majority of tracking discrepancies. [6]
- Wearable device inaccuracy: Consumer fitness watches and chest straps frequently overestimate calories burned during resistance workouts by 20% to 40% (Düking et al. 2020). Never add back all "active calories" estimated by a wearable into your daily food budget; use the static activity multiplier as your primary control.
- Food label tolerances: Under FDA and European regulatory frameworks, packaged food labels are legally permitted up to a 20% margin of error in declared caloric and macronutrient values. Treat your calculated TDEE as an educated hypothesis to be refined against your 2- to 3-week scale average trend.
Frequently asked questions about calorie calculation
How can I figure out my exact calorie deficit?
Determine your maintenance TDEE using the calculator above, then subtract between 300 and 500 calories per day. Track your morning bodyweight every day for two weeks and calculate the weekly average. If your average weight drops by 0.5 to 1.0 pound (0.25 to 0.5 kg) per week, your deficit is dialed in correctly. If weight is unchanged after 2 weeks, reduce daily intake by another 150–200 calories.
What is the difference between BMR and TDEE?
BMR (Basal Metabolic Rate) is the energy your body burns strictly to stay alive in a coma-like state with no movement or digestion. TDEE (Total Daily Energy Expenditure) is your total actual energy expenditure across 24 hours, adding BMR together with the thermic effect of food (TEF), exercise activity (EAT), and non-exercise daily movement (NEAT).
How long will it take to lose 20 pounds eating at a 500 calorie deficit?
At a steady 500 calorie daily deficit, theoretical weight loss is approximately 1 pound per week, meaning 20 pounds would take approximately 20 to 24 weeks (5 to 6 months). In practice, early weight loss is faster due to glycogen water loss, while later weight loss slows due to metabolic adaptation, making 20–26 weeks a realistic timeline.
Is 1,200 calories enough per day for weight loss?
For most adult women, 1,200 calories is the absolute clinical lower bound, not an optimal target. While very petite, sedentary women may occasionally diet near 1,200 kcal, active individuals or taller women will experience excessive fatigue, hormonal disruption, and muscle loss at this intake. Men should virtually never diet below 1,500 kcal per day without direct physician supervision.
How many calories should I eat to build muscle without gaining fat?
To build muscle while minimizing adipose tissue gain (a "lean bulk"), consume a modest surplus of 200 to 300 calories above maintenance TDEE (roughly 10% above maintenance) combined with progressive resistance training. This supports muscular protein synthesis while avoiding the excess fat gain associated with aggressive bulking.
Do I need to track calories forever?
No. Tracking calories with an app or food journal for 8 to 12 weeks serves as nutritional education, teaching you portion awareness, macronutrient density, and calorie realities. Many lifters transition successfully to intuitive portion-control habits once they internalize their baseline nutritional needs.
Sources
- Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO (1990). A new predictive equation for resting energy expenditure in healthy individuals. American Journal of Clinical Nutrition, 51(2), 241–247.
- Roza AM, Shizgal HM (1984). The Harris Benedict equation reevaluated: resting energy requirements and the body cell mass. American Journal of Clinical Nutrition, 40(1), 168–182.
- Katch FI, McArdle WD (1988). Nutrition, Weight Control, and Exercise (3rd ed.). Lea & Febiger, Philadelphia.
- Hall KD, Sacks G, Chandramohan D, et al. (2011). Quantification of the effect of energy imbalance on bodyweight. The Lancet, 378(9793), 826–837.
- Donnelly JE, Blair SN, Jakicic JM, et al. (2009). American College of Sports Medicine Position Stand. Appropriate physical activity intervention strategies for weight loss and prevention of weight regain for adults. Medicine & Science in Sports & Exercise, 41(2), 459–471.
- Lichtman SW, Pisarska K, Berman ER, et al. (1992). Discrepancy between self-reported and actual caloric intake and exercise in obese subjects. New England Journal of Medicine, 327(27), 1893–1898.
- Morton RW, Murphy KT, McKellar SR, et al. (2018). A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. British Journal of Sports Medicine, 52(6), 376–384.
- Helms ER, Aragon AA, Fitschen PJ (2014). Evidence-based recommendations for natural bodybuilding contest preparation: nutrition and supplementation. Journal of the International Society of Sports Nutrition, 11, 20.