Calorie Calculator (2026)

What Is a Calorie?

A calorie (technically a kilocalorie, kcal) is a unit of energy. In nutrition, it measures the amount of energy that food and drinks provide to your body. Your body uses this energy for every function: breathing, pumping blood, thinking, moving, digesting food, and repairing tissue. If you consistently take in more calories than you burn, the surplus is stored as body fat. If you consistently burn more than you take in, your body draws on fat stores for energy and you lose weight.

• 1 dietary calorie = 1 kilocalorie (kcal) = 4.184 kilojoules
• Carbohydrates provide 4 calories per gram
• Protein provides 4 calories per gram
• Fat provides 9 calories per gram
• Alcohol provides 7 calories per gram (with no essential nutrients)
• 1 pound of body fat stores approximately 3,500 calories of energy
• Energy balance (calories in vs. calories out) determines body weight over time

What Is BMR (Basal Metabolic Rate)?

Basal Metabolic Rate (BMR) is the number of calories your body burns every 24 hours while at complete rest — lying still, not digesting food, at a comfortable temperature. It represents the energy required to sustain core life functions: heartbeat, breathing, brain activity, kidney function, liver function, and cellular repair. BMR is the largest component of total calorie burn for most people.

• BMR accounts for 60–75% of total daily calorie expenditure for most sedentary adults
• Muscle tissue burns more calories at rest than fat tissue — more muscle = higher BMR
• BMR decreases with age at roughly 1–2% per decade after age 20
• Men typically have a higher BMR than women due to greater average muscle mass
• Extreme calorie restriction can lower BMR by 10–20% through metabolic adaptation
• Thyroid hormones are the primary regulators of BMR

BMR is different from RMR (Resting Metabolic Rate). RMR is measured after a 3–4 hour fast in a resting but not fully post-absorptive state, and is typically 10–20% higher than true BMR. Most online calculators, including this one, calculate RMR-level values using the Mifflin-St Jeor equation, which is still labeled "BMR" by convention.

The Mifflin-St Jeor Equation Explained

The Mifflin-St Jeor equation was developed in 1990 by MD Mifflin and ST St Jeor and is currently recommended by the Academy of Nutrition and Dietetics (AND) as the most accurate method for estimating BMR in healthy adults. A 2005 AND meta-analysis found it predicted measured resting metabolic rate within 10% for 82% of non-obese individuals — outperforming the older Harris-Benedict equation.

Men: BMR = (10 × weight_kg) + (6.25 × height_cm) − (5 × age_years) + 5
Women: BMR = (10 × weight_kg) + (6.25 × height_cm) − (5 × age_years) − 161

• Weight (kg): Multiply pounds by 0.4536 to convert to kilograms.
• Height (cm): Multiply total inches by 2.54 to convert to centimeters.
• Age: Use full years (round down).
• Sex constant: The only difference between the male and female formula is the final constant: +5 for men, −161 for women. This reflects the average difference in lean body mass.

What Is TDEE (Total Daily Energy Expenditure)?

Total Daily Energy Expenditure (TDEE) is the total number of calories your body burns in a 24-hour period, accounting for all physical activity on top of your BMR. TDEE is your true maintenance calorie level — eating exactly at your TDEE will keep your weight stable. TDEE is calculated by multiplying BMR by an activity factor.

TDEE has four components:

• BMR (60–75%): Calories burned at rest for basic survival.
• TEF — Thermic Effect of Food (8–15%): Calories burned digesting, absorbing, and metabolizing food. Protein has the highest TEF (20–30%), followed by carbs (5–10%) and fat (0–3%).
• EAT — Exercise Activity Thermogenesis (5–20%): Calories burned during intentional exercise.
• NEAT — Non-Exercise Activity Thermogenesis (15–30%): Calories burned through all non-exercise movement: walking, fidgeting, standing, typing. NEAT is highly variable and a major reason two people with the same BMR can have very different TDEEs.

Activity Level Multipliers

To calculate TDEE, multiply your BMR by the activity factor that best describes your week. Be honest — most people overestimate their activity level, which leads to overestimating calorie needs.

Source: Harris-Benedict activity factors, the standard used across clinical nutrition and most validated calorie calculators worldwide.

Calorie Goals by Objective

Worked Examples

Daily Calorie Needs by Age & Sex

The table below shows estimated daily calorie needs based on the 2020–2025 U.S. Dietary Guidelines for Americans, which are based on Estimated Energy Requirements (EER) derived from doubly labeled water studies. Values assume moderate activity level.

Source: 2020–2025 Dietary Guidelines for Americans, Table A1-1. Sedentary individuals need 200–400 fewer calories; very active individuals need 400–600 more calories than shown.

Macronutrients & How Many Calories Each Provides

Once you know your total daily calorie target, the next step is deciding how to distribute those calories across the three macronutrients. Each macronutrient provides a specific number of calories per gram and plays a distinct role in your body.

Protein targets by goal:

• General health and maintenance: 0.8 g per kg of body weight per day (RDA minimum)
• Weight loss (preserving muscle): 1.2–1.6 g per kg of body weight per day
• Muscle gain (hypertrophy): 1.6–2.2 g per kg of body weight per day
• Older adults (65+): 1.0–1.2 g per kg per day to minimize age-related muscle loss

How to Cut Calories Safely and Sustainably

• Set a moderate deficit (300–500 kcal/day). Larger deficits accelerate muscle loss, cause fatigue, and are harder to maintain.
• Prioritize protein at every meal. Protein is the most satiating macronutrient and protects lean muscle during a calorie deficit. Aim for 25–35 g of protein per meal.
• Fill half your plate with non-starchy vegetables. They are extremely low in calories but high in fiber, water, and micronutrients — making meals more filling without adding significant calories.
• Reduce liquid calories. Sodas, juices, alcohol, and sweetened coffees add 150–500+ calories per serving without contributing to fullness. Water, unsweetened tea, and black coffee have near-zero calories.
• Eat whole, minimally processed foods. Whole foods are more satiating, have higher TEF (thermic effect), and make it easier to stay within your calorie target without constant tracking.
• Track your intake for at least 2–4 weeks. Studies consistently show that people underestimate food intake by 30–40% without tracking. Use a food diary or app to calibrate your sense of portions.
• Allow planned flexibility. One higher-calorie day per week does not derail a calorie deficit. Rigid perfection leads to all-or-nothing thinking and is the most common cause of diet abandonment.

Common Food Calorie Reference

Understanding the calorie density of common foods helps you make better choices without needing to weigh everything. All values are approximate per standard serving.

Source: USDA FoodData Central (FDC). Values rounded to nearest whole number. Calorie content varies by brand, preparation method, and ripeness.

Common Calorie Counting Mistakes

• Overestimating activity level. Choosing "Very Active" when your actual week is 3 moderate gym sessions adds 300–500 calories to your calculated TDEE — enough to completely erase your intended deficit.
• Not accounting for cooking oils and sauces. A tablespoon of oil adds 120 calories; salad dressings, sauces, and marinades commonly add 100–300 calories that go unlogged.
• Measuring by volume instead of weight. Dry ingredients like oats, nuts, and pasta are much denser than they appear. A "cup" of almonds can vary by 50+ calories depending on how tightly packed it is. A kitchen scale is the only accurate method.
• Eating back all exercise calories. Fitness trackers and cardio machines overestimate calorie burn by 20–100%. Eating back all of these calories often eliminates the intended deficit.
• Ignoring weekend intake. Studies show people eat 300–500 more calories on Friday–Sunday than weekdays. A perfect deficit on weekdays offset by weekend overeating explains many "I'm not losing weight" scenarios.
• Assuming lower calories always means faster fat loss. Below roughly 1,200 kcal/day, metabolic adaptation, muscle catabolism, and hormone disruption make severe restriction counterproductive for most people.
• Not re-calculating as weight changes. As you lose weight, your BMR and TDEE decrease. A calorie target set at 180 lbs will put you in less of a deficit at 160 lbs — recalculate every 10–15 lbs lost.

Glossary

Calorie (kcal)

A unit of energy equal to 1 kilocalorie; the standard measure of food energy in nutrition.

BMR — Basal Metabolic Rate

Calories burned at complete rest over 24 hours to maintain core life functions. Calculated using the Mifflin-St Jeor equation in this calculator.

TDEE — Total Daily Energy Expenditure

Total calories burned in a day including all physical activity. TDEE = BMR × activity factor. Your maintenance calorie level.

Calorie deficit

Eating fewer calories than your TDEE. A deficit of 500 kcal/day leads to roughly 1 lb of fat loss per week.

Calorie surplus

Eating more calories than your TDEE. Required for muscle gain, paired with resistance training.

Mifflin-St Jeor equation

The most accurate BMR prediction formula for most adults, developed in 1990 and validated as the preferred method by the Academy of Nutrition and Dietetics.

Macronutrients (macros)

The three main nutrient categories that provide calories: carbohydrates (4 kcal/g), protein (4 kcal/g), and fat (9 kcal/g).

NEAT — Non-Exercise Activity Thermogenesis

Calories burned through all movement that is not deliberate exercise: walking, standing, fidgeting. Highly variable between individuals.

TEF — Thermic Effect of Food

Calories burned digesting, absorbing, and metabolizing food. Protein has the highest TEF (20–30%); fat the lowest (0–3%).

Metabolic adaptation

A reduction in TDEE (beyond what body weight change would predict) in response to prolonged calorie restriction. The body becomes more efficient to conserve energy.

Frequently Asked Questions

Q: How many calories should I eat per day?

A: Most adults need between 1,600 and 3,000 calories per day. The exact number depends on your sex, age, height, weight, and activity level. Use the Mifflin-St Jeor equation to calculate your BMR, then multiply by your activity factor to get your TDEE — that is your maintenance level. Subtract 500 cal/day to lose ~1 lb/week, or add 300–500 cal/day to gain muscle.

Q: What is BMR (Basal Metabolic Rate)?

A: BMR is the number of calories your body burns every day at complete rest to sustain basic life functions — breathing, circulation, organ function, and cellular repair. It accounts for 60–75% of total daily calorie burn and is calculated using the Mifflin-St Jeor equation: for men, BMR = (10 × weight_kg) + (6.25 × height_cm) − (5 × age) + 5; for women, BMR = (10 × weight_kg) + (6.25 × height_cm) − (5 × age) − 161.

Q: What is TDEE?

A: TDEE (Total Daily Energy Expenditure) is the total calories your body burns in 24 hours, including all activity. TDEE = BMR × activity factor. A sedentary person multiplies BMR by 1.2; a very active person multiplies by 1.725. TDEE is your maintenance calorie level — eating at TDEE keeps your weight stable.

Q: How many calories do I need to lose weight?

A: Eat 300–500 fewer calories than your TDEE each day. A 500 kcal/day deficit creates a 3,500 kcal/week deficit, which corresponds to approximately 1 pound of fat loss per week. For most adults, this means eating between 1,400 and 2,200 calories per day. Do not go below 1,200 kcal/day (women) or 1,500 kcal/day (men) without medical supervision.

Q: What is the Mifflin-St Jeor equation and why is it the most accurate?

A: The Mifflin-St Jeor equation (1990) is the most accurate widely-used BMR formula, validated by a 2005 Academy of Nutrition and Dietetics meta-analysis. It correctly predicted measured metabolic rate within 10% for 82% of non-obese subjects — better than the Harris-Benedict, Schofield, or FAO/WHO equations. The formula is: Men: (10 × kg) + (6.25 × cm) − (5 × age) + 5; Women: (10 × kg) + (6.25 × cm) − (5 × age) − 161.

Q: How many calories are in 1 pound of fat?

A: Approximately 3,500 calories are stored in 1 pound of body fat. This is why a consistent daily deficit of 500 calories leads to roughly 1 pound of fat loss per week (500 × 7 = 3,500). In practice, weight loss is not perfectly linear because water retention, glycogen stores, and metabolic adaptation also affect the scale.

Q: Do calorie needs change with age?

A: Yes. BMR decreases by roughly 1–2% per decade after age 20, primarily because muscle mass decreases with age (a process called sarcopenia). A 60-year-old typically needs 200–400 fewer calories per day than a 25-year-old of the same height, weight, and activity level. Protein needs, however, do not decrease and may actually increase in older adults to preserve muscle.

Q: How many calories do I need to build muscle?

A: To build muscle, eat 200–500 calories above your TDEE daily, combined with consistent resistance training and adequate protein (1.6–2.2 g/kg body weight/day). A lean bulk at +200–300 cal/day minimizes fat gain and is preferred by most people who have already achieved a healthy body composition. Beginners can often gain muscle even in a calorie deficit ("newbie gains"), but this effect diminishes quickly.

Q: Is a calorie calculator accurate?

A: Calorie calculators using the Mifflin-St Jeor equation are accurate within ±10% for most adults. The biggest source of error is the activity factor — most people overestimate their activity level. Use the calculator result as a starting point, track your intake and weight for 2–3 weeks, then adjust by 100–200 kcal/day if your weight is not moving in the expected direction. Your body is the ultimate feedback loop.