Daily Energy Calculator: How Many Calories You Burn

A daily energy calculator estimates your total daily energy expenditure (TDEE)—the number of calories you burn in 24 hours—based on your age, sex, weight, height, and activity level. You enter those details, and it returns your maintenance calories, which is the amount you need to eat to keep your weight steady. This number is the starting point for weight loss, gain, or maintenance plans.

Formula

The calculator uses the Mifflin-St Jeor equation to find your basal metabolic rate (BMR), then multiplies it by an activity factor. The formula is:

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

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

TDEE = BMR × activity factor

Where:

• weight is in kilograms (1 kg = 2.2 lb)
• height is in centimeters (1 inch = 2.54 cm)
• age is in years
• activity factor is 1.2 (sedentary), 1.375 (light exercise 1–3 days/week), 1.55 (moderate 3–5 days), 1.725 (active 6–7 days), or 1.9 (very active, physical job or intense training)

Worked Example

Take the default values: a 30-year-old man, 70 kg, 170 cm, moderate activity (factor 1.55).

1. BMR = 10×70 + 6.25×170 − 5×30 + 5 = 700 + 1062.5 − 150 + 5 = 1617.5 kcal/day
2. TDEE = 1617.5 × 1.55 = 2507.125 ≈ 2507 kcal/day

The calculator shows 2507 kcal/day, which matches.

What the Result Means

Your TDEE is the number of calories your body burns each day, including the energy needed just to keep you alive (BMR) plus everything you do—walking, thinking, digesting food, and exercising. If you eat exactly that many calories, your weight stays the same. To lose weight, you need a calorie deficit (eat less than TDEE); to gain weight, you need a surplus. A common guideline is that one pound of body fat equals roughly 3,500 calories, so a daily deficit of 500 calories leads to about one pound lost per week—though individual results vary.

The result is an estimate, not a precise measurement. Real metabolic rates differ by genetics, muscle mass, hormones, and even sleep. Use it as a starting point and adjust based on what the scale shows over a few weeks.

How to Choose Your Activity Level

Be honest with yourself when picking an activity factor. Most people overestimate their activity.

• Sedentary (1.2): desk job, no exercise, mostly sitting all day
• Light (1.375): light exercise 1–3 days per week, or a job that involves some standing/walking
• Moderate (1.55): exercise 3–5 days per week at a moderate intensity
• Active (1.725): hard exercise 6–7 days per week, or a physically demanding job
• Very active (1.9): intense daily training, two-a-day workouts, or heavy manual labor

If you’re unsure, choose the lower option. You can always adjust later.

Common Mistakes and Limits

Unit mix-ups are the most frequent error. The formula requires kilograms and centimeters. If you use pounds and inches, you must convert first: divide pounds by 2.2 to get kg, and multiply inches by 2.54 to get cm. A 180 lb person is 81.8 kg, not 180 kg—that would more than double the result.

Another mistake is using your “goal weight� instead of your current weight. The formula is based on your current body to estimate current energy needs. If you want to know calories for a target weight, you’d need to recalculate after you reach it.

Also, the Mifflin-St Jeor equation is less accurate for extremely muscular or very obese individuals. It tends to underestimate needs for athletes and overestimate for people with very low muscle mass. It’s a general tool, not a medical measurement.

Why It Matters for Weight Management

Your daily energy expenditure is the foundation of any weight change. Without knowing your TDEE, you’re guessing how many calories to eat. For example, if your TDEE is 2,500 kcal and you eat 2,000 kcal, you create a 500 kcal deficit. Over a week, that’s 3,500 kcal—about one pound of fat. Conversely, eating 3,000 kcal would create a surplus that leads to weight gain.

But the number is only part of the story. The quality of calories matters for health and satiety. Protein and fiber help you feel full, which makes a deficit easier to maintain. Also, exercise not only burns calories but can increase your BMR by building muscle, which raises your resting energy expenditure.

Alternatives to the Mifflin-St Jeor Equation

Other formulas exist, each with its own strengths:

• Harris-Benedict (revised): older, slightly different constants, tends to overestimate in some populations
• Katch-McArdle: uses lean body mass, so it’s more accurate for athletes but requires body fat percentage
• Mifflin-St Jeor: generally considered the most accurate for average adults, which is why it’s used here

For most people, the Mifflin-St Jeor equation gives a good starting estimate. If you know your body fat percentage, the Katch-McArdle formula might be more precise, but the difference is usually small for non-athletes.

Frequently Asked Questions

How many calories should I eat to lose weight?

Subtract 300–500 calories from your TDEE for gradual weight loss of about 0.5–1 lb (0.2–0.45 kg) per week. A smaller deficit is easier to sustain and less likely to cause muscle loss. Avoid going below your BMR for extended periods; that can slow metabolism and cause nutrient deficiencies.

Is this calculator accurate?

It’s accurate within about 10% for most people. Individual variation comes from genetics, muscle mass, and even the type of food you eat (protein requires more energy to digest). Use the result as a baseline and track your weight for two weeks to fine-tune your intake.

Do I need to eat back exercise calories?

Generally no. The activity factor already accounts for your exercise. If you use a moderate activity level and then also eat back every calorie you burn in a workout, you’ll likely overeat. Only if you do an unusually intense session (like a marathon) might you need extra fuel.

What is BMR vs TDEE?

BMR is the calories your body burns at complete rest, just to keep your heart beating, lungs breathing, and cells working. TDEE is BMR plus all the energy for movement, digestion, and daily activities. TDEE is always higher than BMR unless you’re in a coma.

Can I use this if I’m pregnant or breastfeeding?

The formula does not account for the extra energy needs of pregnancy or lactation. Pregnant women typically need an additional 300–450 kcal/day in the second and third trimesters, and breastfeeding adds about 500 kcal/day. Consult a healthcare provider for personalized advice.

Why is my result different from a fitness tracker?

Fitness trackers estimate calories burned using heart rate and motion, but they can be off by 20–30%. This calculator uses your body stats and activity level, which is a more consistent estimate. Trust the calculator for baseline, and use the tracker only to see trends.

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in age | Age | years | 30 | 18
in sex | Sex | Male=1, Female=0 | 1 | 0
in weight | Weight | kg | 70 | 30
in height | Height | cm | 170 | 100
sel activity | Activity Level | Sedentary=1.2, Light=1.375, Moderate=1.55, Active=1.725, Very Active=1.9
out tdee | Daily energy expenditure | kcal/day | (10 * weight + 6.25 * height - 5 * age + (sex == 1 ? 5 : -161)) * activity | 0
out bmr | Basal metabolic rate | kcal/day | 10 * weight + 6.25 * height - 5 * age + (sex == 1 ? 5 : -161) | 0