Calorie Calculator
Calculate your daily calorie needs based on age, sex, height, weight, and activity level using the Mifflin-St Jeor equation, the most accurate BMR equation.
This free online calorie calculator provides instant results with no signup required. All calculations run directly in your browser — your data is never sent to a server. Enter your values below and see results update in real time as you type. Perfect for everyday calculations, homework, or professional use.
How to Use This Calculator
Enter your input values
Fill in all required input fields for the Calorie Calculator. Most fields include unit selectors so you can work in your preferred unit system — metric or imperial, whichever matches your problem.
Review your inputs
Double-check that all values are correct and that you have selected the right units for each field. Incorrect units are the most common source of calculation errors and can produce results that are off by factors of 2, 10, or more.
Read the results
The Calorie Calculator instantly computes the output and displays results with units clearly labeled. All calculations happen in your browser — no loading time and no data sent to a server.
Explore parameter sensitivity
Try adjusting individual input values to see how the output changes. This is a quick and effective way to develop intuition about how different parameters influence the result and to identify which inputs have the largest effect.
Formula Reference
Calorie Calculator Formula
See calculator inputs for the governing equation
Variables: All variables and their units are labeled in the calculator interface above. Input fields accept values in multiple unit systems — select your preferred unit from the dropdown next to each field.
When to Use This Calculator
- •Use the Calorie Calculator for personal health tracking and wellness monitoring, establishing a baseline and tracking changes over time.
- •Use it when recording fitness metrics to track progress toward health or athletic goals.
- •Use it to compare measurements before and after a lifestyle, diet, or training change to quantify the impact.
- •Use it as a conversation starter before a doctor's appointment, bringing objective data to discuss with a healthcare professional.
About This Calculator
The Calorie Calculator is a free health and wellness calculation tool designed for personal use and general informational purposes. Calculate your daily calorie needs based on age, sex, height, weight, and activity level using the Mifflin-St Jeor equation, the most accurate BMR equation. This calculator provides reference values based on established health screening formulas and should not be used as a substitute for professional medical advice, diagnosis, or treatment. Results may vary based on individual factors not captured by the calculation. Consult a qualified healthcare provider for personalized health guidance. All calculations are performed locally in your browser — no personal health data is transmitted or stored.
About Calorie Calculator
The Calorie Calculator estimates your daily caloric needs using the Mifflin-St Jeor equation, which the American Dietetic Association considers the most accurate predictive equation for BMR. Your BMR is the number of calories your body burns at rest to maintain vital functions. By multiplying BMR by an activity factor, you get your Total Daily Energy Expenditure (TDEE) — the total calories you need to maintain your current weight. This calculator also shows calorie targets for weight loss and weight gain, calculated at the commonly recommended ±500 kcal/day deficit or surplus.
The Math Behind It
Formula Reference
Mifflin-St Jeor (1990)
BMR = 10W + 6.25H - 5A + S
Variables: W = weight (kg), H = height (cm), A = age, S = +5 (male) or -161 (female)
TDEE
TDEE = BMR × Activity Factor
Variables: Activity Factor: 1.2-1.9
Worked Examples
Example 1: Active 30-Year-Old Male
Male, 30, 80 kg, 180 cm, exercises 3-5 days/week
Maintenance: ~2,759 kcal/day. To lose 0.5 kg/week: ~2,259 kcal/day.
Example 2: Sedentary 25-Year-Old Female
Female, 25, 60 kg, 165 cm, sedentary
Maintenance: ~1,614 kcal/day. Weight loss at -500 kcal: ~1,114 kcal/day (note: below 1,200 kcal requires medical supervision).
Common Mistakes & Tips
- !Setting an extreme calorie deficit (>1,000 kcal/day). Causes metabolic adaptation, muscle loss, and is unsustainable.
- !Overestimating activity level. Most people with desk jobs who exercise 3x/week are 'Lightly Active', not 'Moderately Active'.
- !Using this calculator for children or pregnant/lactating women, who have different metabolic needs.
Related Concepts
Used in These Calculators
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Frequently Asked Questions
Is the Mifflin-St Jeor equation better than Harris-Benedict?
Yes, for most people. A 2005 review found Mifflin-St Jeor predicted BMR within 10% of measured values more often than Harris-Benedict, especially for obese individuals.
How many calories should I eat to lose weight?
A deficit of 500 calories per day leads to approximately 0.5 kg (1 lb) of fat loss per week. Never go below 1,200 kcal/day (women) or 1,500 kcal/day (men) without medical supervision.
Should I eat back the calories I burn during exercise?
The activity multiplier already accounts for your general exercise level. Most fitness trackers significantly overestimate exercise calories, so eating back 100% often leads to weight gain.