Calorie & TDEE Calculator: How Many Calories Do You Need?

What Is TDEE?

TDEE stands for Total Daily Energy Expenditure. It's the total number of calories your body uses in a 24-hour period — not just at rest, but accounting for everything: digesting food, walking to your car, typing at a desk, and any structured exercise.

TDEE is made up of four components:

• BMR (Basal Metabolic Rate): Calories burned at complete rest — roughly 60–75% of TDEE for sedentary people.
• TEF (Thermic Effect of Food): Energy used to digest and absorb food — roughly 10% of total calories eaten.
• NEAT (Non-Exercise Activity Thermogenesis): All movement that isn't structured exercise: fidgeting, walking, household tasks. This is highly variable — research in Science found NEAT differences of up to 2,000 calories/day between individuals.
• EAT (Exercise Activity Thermogenesis): Calories burned during deliberate exercise sessions.

When you know your TDEE, you know your maintenance calories. Eat below it to lose weight, above it to gain.

The Mifflin-St Jeor Equation: The Gold Standard

Not all calorie formulas are created equal. The Mifflin-St Jeor equation, developed in 1990 and validated in multiple independent studies, is the formula most registered dietitians now use. A meta-analysis in the Journal of the American Dietetic Association found it predicted resting metabolic rate more accurately than Harris-Benedict in 82% of test subjects.

For men:

BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) + 5

For women:

BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) − 161

Example: A 30-year-old woman, 165 cm tall, weighing 68 kg:
BMR = (10 × 68) + (6.25 × 165) − (5 × 30) − 161
BMR = 680 + 1031.25 − 150 − 161
BMR = 1,400 calories/day

That's her BMR — what she burns lying completely still. Multiply by an activity factor to get her real daily need (TDEE).

BMR Formula Comparison: Mifflin-St Jeor vs Harris-Benedict

Our Calorie & TDEE Calculatoruses Mifflin-St Jeor by default. If you know your body fat percentage, the Katch-McArdle formula may be even more precise — lean mass drives metabolic rate more directly than total weight.

Activity Multipliers: Choosing the Right Level

Once you have your BMR, multiply it by an activity factor to get your TDEE. This is where most people go wrong — the NIH notes that people consistently overestimate their physical activity levels, which leads to eating more than intended.

Using the woman from our earlier example (BMR = 1,400) at a moderately active level:
TDEE = 1,400 × 1.55 = 2,170 calories/day

That's her maintenance calorie intake. Eat there and her weight stays stable. Eat 500 below (1,670/day) and she loses roughly 1 lb/week.

5 Steps to Calculate Your TDEE

1. Get your weight and height in metric units. Divide pounds by 2.205 for kg. Multiply inches by 2.54 for cm.
2. Calculate your BMR using the Mifflin-St Jeor equation above, or use our free calculator to skip the math.
3. Choose your activity multiplier honestly. If you sit most of the day with 3 gym sessions per week, you're lightly to moderately active — not very active.
4. Multiply BMR × activity factor to get your TDEE (maintenance calories).
5. Set your goal: subtract 250–500 cal/day to lose weight, add 250–500 cal/day to gain muscle, or eat at TDEE to maintain.

Calorie Deficit and Surplus: How to Set Targets

A 3,500-calorie deficit equals roughly 1 pound of fat loss. That's the widely cited figure from research by Max Wishnofsky, MD, published in 1958 and still referenced in CDC guidelines. The math is straightforward:

• -500 cal/day: ~1 lb/week fat loss
• -250 cal/day: ~0.5 lb/week fat loss (slower, more sustainable)
• +250 cal/day: ~0.5 lb/week muscle gain (lean bulk, minimal fat)
• +500 cal/day: ~1 lb/week total gain (some fat, some muscle)

The CDC recommends losing no more than 1–2 lbs per week to preserve lean muscle mass and metabolic rate. Faster deficits (>1,000 cal/day below TDEE) tend to cause muscle loss, increased hunger, and metabolic adaptation — your body downregulates TDEE as a response.

A 2014 study in the American Journal of Clinical Nutrition found that subjects in a 25% calorie deficit who combined resistance training with protein intake above 1.6g/kg lost significantly more fat and preserved more muscle than those doing cardio alone. Pair your calorie target with adequate protein — our protein intake calculator can help set that number.

How Calorie Needs Change Over Time

TDEE isn't static. Several factors shift it up or down:

Age

The NIH estimates that metabolic rate declines by roughly 2–3% per decade after age 30. This is partly due to muscle mass loss (sarcopenia) — muscle is metabolically active tissue, and less of it means fewer calories burned at rest. Strength training mitigates this.

Muscle Mass

A pound of muscle burns roughly 6 calories/day at rest vs 2 calories/day for a pound of fat. It's not a dramatic difference per pound, but an extra 10 lbs of lean mass adds ~40 extra calories burned daily — meaningful over time.

Weight Loss Itself

As you lose weight, your TDEE drops because you're carrying less mass. A common mistake is not adjusting calories as you shed pounds. Recalculate your TDEE every 10–15 lbs lost to avoid a plateau.

Metabolic Adaptation

Prolonged calorie restriction causes “adaptive thermogenesis” — the body reduces TDEE beyond what weight loss alone would predict. A landmark study in Obesity following Biggest Loser contestants found their TDEEs were 500 calories lower than predicted even 6 years after the show. This is why diet breaks and maintenance phases matter.

Calorie Counting: Does It Work?

Research is mixed on long-term calorie counting, but the fundamentals hold. A 2019 JAMA Internal Medicine study of 600+ adults found both low-fat and low-carb dieters lost similar amounts of weight when both groups reduced processed food and ate to satiety — suggesting food quality matters as much as strict counting.

That said, knowing your TDEE gives you a framework. You don't need to weigh every gram forever. Use it to calibrate portion sizes for a few weeks, then rely on hunger cues. If your weight trends up, you're above TDEE. If it trends down, you're below it. The scale is real-time feedback.

For macronutrient breakdown alongside calories, check our macro calculator. For bodyweight-specific protein needs, the protein intake calculator gives targets based on activity level and goal. And if you want to track BMI alongside TDEE, our BMI calculator gives instant context.

Common TDEE Mistakes

Overestimating Activity Level

Going to the gym 4 days a week does not make you “very active” if you sit 8 hours at a desk otherwise. Choose the multiplier for your full day, not just your workout. A desk worker who exercises 4 days/week is moderately active at best.

Not Recalculating After Weight Changes

Your TDEE 20 lbs ago is not your TDEE today. Recalculate every time your weight changes significantly.

Ignoring Water Weight Noise

Day-to-day weight fluctuations of 1–4 lbs are normal and reflect water, sodium, glycogen, and digestive content — not fat. Judge your calorie target by a 2–3 week weight trend, not a single weigh-in.

Eating Too Little

Dropping below 1,200 calories (women) or 1,500 calories (men) daily triggers adaptive thermogenesis and muscle breakdown. The USDA Dietary Guidelines recommend never going below 1,200 calories without medical supervision.

Frequently Asked Questions

What is TDEE and how many calories should I eat?

TDEE (Total Daily Energy Expenditure) is the total number of calories your body burns in a day, including exercise. To maintain weight, eat at your TDEE. To lose weight, eat 500 calories below it. To gain muscle, eat 250–500 calories above it. Most adults need 1,600–3,000 calories daily depending on size and activity level.

What is the Mifflin-St Jeor equation?

The Mifflin-St Jeor equation is the most accurate formula for calculating BMR (Basal Metabolic Rate). For men: BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) + 5. For women: subtract 161 instead of adding 5. Multiply by your activity factor to get TDEE. It's more accurate than Harris-Benedict for most people, per the Journal of the American Dietetic Association.

How many calories should I eat to lose 1 pound per week?

To lose 1 pound per week, eat 500 fewer calories than your TDEE each day — a 3,500-calorie weekly deficit matches roughly 1 pound of fat. For 0.5 pounds per week, cut 250 calories daily. The CDC recommends gradual weight loss of 1–2 pounds per week for sustainable results and health preservation.

What activity multiplier should I use for TDEE?

Use 1.2 if sedentary (desk job, little exercise), 1.375 if lightly active (exercise 1–3 days/week), 1.55 if moderately active (exercise 3–5 days/week), 1.725 if very active (hard exercise 6–7 days/week), and 1.9 if extremely active (physical job plus heavy daily training). Most people overestimate activity — when in doubt, choose one level lower.

Is TDEE the same as BMR?

No. BMR (Basal Metabolic Rate) is the calories your body burns at complete rest — just to keep organs functioning. TDEE is BMR multiplied by an activity factor that accounts for all movement and exercise. TDEE is always higher than BMR. For a sedentary person, TDEE is roughly 1.2x their BMR.

How accurate are online TDEE calculators?

Calculators using the Mifflin-St Jeor equation are accurate within 10% for most people, per the Journal of the American Dietetic Association. The biggest error source is activity level. Track your weight for 2–3 weeks after setting a calorie target and adjust by 100–200 calories if progress stalls or is faster than expected.

Should I eat back calories burned during exercise?

It depends on your TDEE method. If you used a sedentary multiplier and added exercise calories on top, eat some back. If you already chose a multiplier that reflects your exercise habits, don't — they're already counted. Eating back 50–75% of tracked exercise calories is a common middle-ground approach for those who want flexibility.