Health

Calorie Calculator Guide: Find Your TDEE for Weight Loss, Muscle Gain & Maintenance

Q: How many calories should I eat to lose weight?

A safe calorie deficit is 500-750 calories per day below your TDEE, which produces about 0.5-1 pound of weight loss per week. The CDC recommends aiming for 1-2 pounds per week; deficits larger than 1,000 calories are hard to sustain and increase muscle loss.

Q: How accurate is the Mifflin-St Jeor calorie calculator?

The Mifflin-St Jeor equation predicts BMR within about 10% for most healthy adults and is considered the most reliable predictive formula by the Academy of Nutrition and Dietetics. Treat the result as a starting estimate, then adjust based on 2-3 weeks of real-world scale and measurement data.

Q: Should I eat back the calories I burn during exercise?

Usually no. The activity multiplier in the TDEE calculation already accounts for your average weekly exercise, and fitness trackers routinely overestimate calorie burn — often by 20-90%. Adding burned calories back on top of an active TDEE double-counts them.

Q: How often should I recalculate my TDEE?

Recalculate whenever your weight changes by roughly 2-4 kg (5-10 pounds), your activity level shifts (new job, new training plan), or a few years of age pass. TDEE falls as you lose weight, which is why a deficit that worked at the start of a diet often stalls months later.

Health Guide · Mifflin-St Jeor TDEE, updated 2026

Almost every nutrition plan — cutting, bulking, or maintaining — starts from the same number: the calories your body actually burns in a day. Guess it wrong and you can "eat clean" for months and still not move the scale. Our free calorie calculator estimates that number in seconds from your age, sex, height, weight, and activity level, using the Mifflin-St Jeor equation — the formula the Academy of Nutrition and Dietetics considers the most reliable way to predict daily energy needs in healthy adults. This guide explains what the number means, where it comes from, and how to turn it into a realistic plan.

What Is TDEE? (And How It Differs from BMR)

BMR — basal metabolic rate — is the energy your body burns at complete rest just to run itself: brain, heart, breathing, cell repair. For most people it is the single largest slice of daily burn, roughly 60-70% of the total.

TDEE — total daily energy expenditure — is BMR plus everything else you do:

BMR (~60-70%): keeping you alive at rest.
NEAT — non-exercise activity thermogenesis: walking, typing, cooking, fidgeting. This varies enormously between people and is a big reason two people with identical stats can burn hundreds of calories differently.
TEF — the thermic effect of food: energy spent digesting and absorbing meals, about 10% of intake.
EAT — exercise activity thermogenesis: workouts and sport.

Eat about your TDEE and your weight holds steady. Eat consistently below it and you lose weight; consistently above it and you gain. Every goal below is just a controlled offset from this one number.

How the Calorie Calculator Works: The Mifflin-St Jeor Equation

The calculator first estimates BMR with the Mifflin-St Jeor equation, published in 1990 and still the standard first estimate:

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

It then multiplies BMR by an activity factor to get TDEE:

Sedentary (desk job, little exercise): × 1.2
Lightly active (light exercise 1-3 days/week): × 1.375
Moderately active (moderate exercise 3-5 days/week): × 1.55
Very active (hard exercise 6-7 days/week): × 1.725
Extra active (physical job plus training): × 1.9

Be honest with the activity level — most people overestimate it. "Moderately active" means regular structured exercise most days, not an occasional walk.

Worked Examples

Example 1: a 30-year-old woman, 165 cm, 60 kg, moderately active.

BMR = 10 × 60 + 6.25 × 165 − 5 × 30 − 161 = 600 + 1,031 − 150 − 161 ≈ 1,320 calories. TDEE = 1,320 × 1.55 ≈ 2,050 calories. That is her maintenance intake.

Example 2: a 35-year-old man, 180 cm, 85 kg, sedentary.

BMR = 10 × 85 + 6.25 × 180 − 5 × 35 + 5 = 850 + 1,125 − 175 + 5 = 1,805 calories. TDEE = 1,805 × 1.2 ≈ 2,165 calories. To lose about a pound a week he would eat around 1,650-1,700.

Run your own numbers in the calorie calculator — it applies both formulas and all five activity levels for you.

Calories for Weight Loss

One pound of body fat stores roughly 3,500 calories of energy, so a daily deficit of 500 calories yields about a pound of loss per week — a useful planning rule. The CDC recommends gradual loss of 1-2 pounds per week, which corresponds to a deficit of roughly 500-1,000 calories per day from diet, activity, or both.

In practice, a deficit of 500-750 calories is the sweet spot for most people: enough to see steady progress, small enough to preserve muscle, energy, and sanity. Two caveats the simple rule ignores:

The 3,500 rule flattens over time. As you lose weight your TDEE falls (a smaller body burns less), and the body adapts by becoming more efficient. A deficit that produced a pound a week in month one may produce half a pound by month four — that is normal, not a broken metabolism. Recalculate your TDEE every few weeks.
Do not crash diet. Very low intakes (under about 800 calories per day) are not recommended without medical supervision. As a rough guardrail, most adults should not eat below their BMR for extended periods on their own.

Concretely: the woman in Example 1 (TDEE ≈ 2,050) would target roughly 1,300-1,550 calories per day for steady loss, and expect to update that target as her weight drops.

Calories for Muscle Gain

Building muscle requires a small energy surplus plus resistance training and enough protein. A surplus of 250-500 calories above TDEE is enough — larger "see-food" bulks mostly add fat, because muscle tissue can only grow so fast (beginners roughly 0.25-0.5 kg per month; the rate declines with training age).

Protein is the other lever: research consistently supports about 1.6-2.2 g per kilogram of body weight per day for people training hard. For the man in Example 2 (85 kg), that is roughly 135-185 g of protein daily, with the surplus calories on top of his ≈ 2,165 maintenance.

Expect the scale to move about 0.25-0.5% of body weight per week on a clean bulk. Faster than that is usually fat. Our BMI calculator and body fat calculator help you check whether the gain is going where you want.

Maintenance: Why TDEE Changes Over Time

TDEE is not a constant. It falls as you lose weight, rises with new training volume, drifts down with age, and shifts with everyday changes — a new desk job, an injury, a more active commute. When your goal is maintenance, recalculate after any meaningful change: roughly every 2-4 kg (5-10 lb) of body-weight change, or whenever your routine changes for more than a couple of weeks.

Also expect daily scale noise of 1-2 kg from water, sodium, and glycogen — judge progress by the 2-3 week trend, not any single morning.

How to Use Our Calorie Calculator

The calorie calculator takes four steps:

Enter your age, sex, height, and weight (metric or imperial).
Pick the activity level that matches your average week — be conservative.
Read your BMR and TDEE. TDEE is your maintenance intake.
Apply your goal: subtract 500-750 for loss, add 250-500 for gain, or hold at TDEE to maintain.

Treat the output as a starting hypothesis, not a prescription. Weigh in under the same conditions a few mornings a week, track the weekly average, and adjust by 100-200 calories if the trend disagrees with the plan for 2-3 weeks straight.

Common Calorie Mistakes to Avoid

Eating back exercise calories — the activity multiplier already counts your workouts, and trackers overestimate burn (often by 20-90%). Do not double-count.
Overestimating activity level — choose the level below the one you think you are if you are unsure; it is the most common source of "I'm eating at a deficit but not losing."
Cutting too aggressively — deficits beyond ~1,000 calories accelerate muscle loss, hunger, and rebound. Slower is faster overall.
Judging progress by daily weight — water swings of 1-2 kg will lie to you. Use weekly averages.
Ignoring protein and fiber — 100 calories of chicken and 100 calories of soda cost the same energy but land completely differently on hunger. Calories decide weight; food quality decides whether the diet is livable.

Frequently Asked Questions

What is TDEE and how is it different from BMR? BMR is the energy your body burns at complete rest just to stay alive. TDEE is BMR plus everything else — daily movement, exercise, and digesting food. TDEE is your maintenance intake: eat that amount and your weight stays roughly stable.

How many calories should I eat to lose weight? A safe deficit is 500-750 calories per day below your TDEE, producing about 0.5-1 pound of loss per week. The CDC recommends aiming for 1-2 pounds per week; deficits larger than 1,000 calories are hard to sustain and increase muscle loss.

How accurate is the Mifflin-St Jeor calorie calculator? It predicts BMR within about 10% for most healthy adults and is considered the most reliable predictive formula by the Academy of Nutrition and Dietetics. Treat the result as a starting estimate, then adjust based on 2-3 weeks of real-world data.

Should I eat back the calories I burn during exercise? Usually no. The activity multiplier already accounts for your average weekly exercise, and fitness trackers routinely overestimate burn — often by 20-90%. Adding burned calories back on top of an active TDEE double-counts them.

How many calories do I need to build muscle? A modest surplus of 250-500 calories above TDEE supports muscle growth while limiting fat gain. Pair it with 1.6-2.2 g of protein per kg of body weight daily and progressive strength training.

How often should I recalculate my TDEE? Whenever your weight changes by roughly 2-4 kg, your activity level shifts, or a few years pass. TDEE falls as you lose weight, which is why a deficit that worked at the start often stalls months later.

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