CodeKitHubWhat Is This Tool?
A calorie calculator estimates how much energy your body burns in a day. It starts from your basal metabolic rate (BMR) — the calories you'd burn at complete rest — calculated here with the Mifflin-St Jeor equation, which studies have found to be the most accurate of the common BMR formulas for most adults. That resting figure is then multiplied by an activity factor (from 1.2 for a sedentary lifestyle up to 1.9 for very hard daily training) to produce your total daily energy expenditure, or TDEE.
TDEE is the number most people actually want: eat roughly that many calories and your weight stays stable; eat consistently below it and you lose weight; eat above it and you gain. This calculator shows all three targets — a moderate deficit of about 500 kcal/day for weight loss, your maintenance level, and a moderate surplus of about 500 kcal/day for weight gain.
Why Use It?
- Uses the Mifflin-St Jeor equation, the formula recommended by the Academy of Nutrition and Dietetics as the most reliable for estimating resting metabolism in adults.
- Shows BMR, TDEE and three practical intake targets (lose / maintain / gain) in one result, not just a single number.
- Five activity levels from sedentary to very active, so the estimate reflects how you actually live, not a generic average.
- Supports metric (cm, kg) and imperial (feet/inches, pounds) units.
- Free and instant, with nothing uploaded — the calculation runs entirely in your browser.
How to Use
- Select your sex and enter your age.
- Enter your height and weight, in metric or imperial units.
- Choose the activity level that best matches a typical week.
- Press the calculate button and read your BMR, your daily maintenance calories (TDEE), and the suggested intakes for losing or gaining weight.
Example
Input
Male, 30 years, 178 cm, 75 kg, moderately activeOutput
BMR ≈ 1,730 kcal — maintenance ≈ 2,680 kcal/dayMifflin-St Jeor: 10×75 + 6.25×178 − 5×30 + 5 = 1,717.5 ≈ 1,730 kcal at rest. Multiplied by the moderate-activity factor of 1.55 gives roughly 2,680 kcal/day to maintain weight; about 2,180 to lose and 3,180 to gain.
Activity level multipliers explained
| Activity level | Multiplier | Typical lifestyle |
|---|---|---|
| Sedentary | 1.2 | Desk job, little or no exercise |
| Lightly active | 1.375 | Light exercise or sport 1–3 days a week |
| Moderately active | 1.55 | Moderate exercise 3–5 days a week |
| Very active | 1.725 | Hard exercise 6–7 days a week |
| Extremely active | 1.9 | Very hard daily exercise or a physical job |
How the three intake targets work
- Lose weight: about 500 kcal below maintenance — roughly 0.5 kg (1 lb) per week for most people, a pace that preserves muscle better than crash deficits.
- Maintain weight: your TDEE itself. Eat around this level and your weight should stay roughly stable over time.
- Gain weight: about 500 kcal above maintenance — suitable for muscle-building phases when combined with resistance training; without training, most of the surplus becomes fat.
- Whatever the target, the calculator is an estimate. Weigh yourself under consistent conditions for a few weeks and adjust by 100–200 kcal at a time if the trend doesn't match your goal.
- This tool provides estimates for general reference only and is not a substitute for professional medical or dietary advice — consult a doctor or registered dietitian for personal guidance.
Related health calculators
Your maintenance calories are built on top of your resting metabolism — if you want to see just that base figure and compare the two standard formulas that estimate it, use the BMR Calculator.
Calories tell you how much energy you use; they don't tell you what your body is made of. The Body Fat Calculator estimates body-fat percentage from tape measurements, the BMI Calculator gives a quick weight-for-height screening number, and the Water Intake Calculator estimates how much you should drink per day.
→ BMR Calculator · Body Fat Calculator · BMI Calculator · Water Intake Calculator
Frequently Asked Questions
Which formula does this calorie calculator use?
The Mifflin-St Jeor equation: for men, BMR = 10×weight(kg) + 6.25×height(cm) − 5×age + 5; for women the same formula ends with −161 instead of +5. Comparative studies have found it more accurate than the older Harris-Benedict equation for most modern adults, which is why dietitians generally prefer it.
What is the difference between BMR and TDEE?
BMR (basal metabolic rate) is the energy your body burns at complete rest, just keeping organs running. TDEE (total daily energy expenditure) is BMR multiplied by an activity factor to account for everything else you do — walking, working, exercising. TDEE is the number to compare your food intake against.
How many calories should I cut to lose weight?
A common, sustainable guideline is a deficit of about 500 kcal below your TDEE, which corresponds to roughly 0.5 kg (1 lb) of weight loss per week. Larger deficits produce faster loss but are harder to sustain and can cost muscle mass. Going below about 1,200 kcal/day (women) or 1,500 kcal/day (men) without medical supervision is generally not recommended.
How accurate is a calorie calculator?
Formulas like Mifflin-St Jeor are typically within about 10% of measured resting metabolism for most adults, but individual factors — muscle mass, genetics, hormones, medications — can push your true needs higher or lower. Use the result as a starting point, track your weight for two to three weeks, and adjust intake up or down based on what actually happens.
Is this medical or dietary advice?
No. This calculator provides general estimates for informational purposes only. If you are pregnant or breastfeeding, under 18, over 65, have a medical condition, or have a history of disordered eating, talk to a doctor or registered dietitian before changing your diet.
Is my data stored anywhere?
No. The calculation runs in your browser with JavaScript; your inputs are never sent to a server, stored or logged.