Calculate your daily calorie needs (TDEE) and get intake recommendations for weight loss, maintenance, or gain.
Your Daily Calorie Needs
About the Calorie Calculator — Calorie Calculator Online & TDEE Calculator
This free calorie calculator online uses the Mifflin-St Jeor equation to estimate your Basal Metabolic Rate (BMR) and Total Daily Energy Expenditure (TDEE) based on your age, gender, height, weight, and activity level. TDEE is how many calories your body actually burns each day once you account for movement. That number is the foundation of any real nutrition plan — whether you're cutting fat, building muscle, or just trying to maintain.
The Mifflin-St Jeor equation was published in 1990 and validated on a broader population than the older Harris-Benedict formula, which tends to overestimate BMR by 5–15%. This calculator supports both imperial and metric inputs and displays your BMR, TDEE, and calorie targets for weight loss, mild weight loss, maintenance, and weight gain — all at once.
How to Use the Calorie Calculator
Select your Unit System — Imperial (feet, inches, pounds) or Metric (centimeters, kilograms) — using the radio buttons at the top of the form.
Enter your Age in years and select your Gender. The Mifflin-St Jeor equation uses different constants for males and females to account for differences in lean mass.
Enter your Height and Weight in the fields shown for your selected unit system. For imperial users, enter feet and inches separately.
Choose your Activity Level from the dropdown. Select Sedentary if you have a desk job with little exercise, Moderately Active for 3–5 days per week of exercise, and Extra Active for a physical job or twice-daily training.
Click Calculate Calories to see your BMR, TDEE, and calorie targets for mild weight loss (−250 cal/day), weight loss (−500 cal/day), maintenance, and weight gain (+500 cal/day).
How the Mifflin-St Jeor Equation Works
The formula calculates resting calorie burn differently for males and females. For men: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5. For women: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161. TDEE is then calculated by multiplying BMR by an activity multiplier ranging from 1.2 (sedentary) to 1.9 (extra active). If you entered imperial measurements, the calculator converts them to metric before running the formula.
Tips for Getting the Best Results
Be honest about activity level: Most people overestimate how active they are. If you exercise 3 times a week but sit at a desk the rest of the time, choose Lightly Active — not Moderately Active. Overestimating leads to an inflated TDEE and unintended overeating.
Treat the result as a starting point: The equation is accurate within about 10% for most people, but individual metabolism varies. Start at your calculated TDEE, track your actual weight change for 2–3 weeks, and adjust up or down by 100–200 calories based on real results.
A modest deficit is usually more sustainable: A 500-calorie daily deficit produces roughly 0.5 kg (1 lb) of fat loss per week in theory. But more aggressive cuts often cause muscle loss and metabolic adaptation. The mild weight loss target (−250 cal/day) is easier to stick to over months.
Recalculate as your weight changes: Losing weight means your BMR drops too — there's less body mass to maintain. Recalculate every 5 kg or so to keep your targets accurate. It's one of the most common reasons fat loss stalls.
Don't go below safe minimums: Eating fewer than 1,200 calories per day for women or 1,500 for men is generally considered unsafe without medical supervision. Extreme deficits risk nutritional deficiencies and lean mass loss.
Why Use a Calorie Calculator Online
Doing this math by hand means multiple steps — unit conversions, gender-specific formulas, then multiplying by an activity factor for each goal. It's easy to get wrong. This calculator handles all of it instantly and shows you four different calorie targets at once. And because it runs entirely in your browser, there's no account to create and your health data never leaves your device.
Dietitians use TDEE calculators as a quick baseline before designing individualized meal plans. Personal trainers use them to set realistic targets for clients. People tracking macros for bodybuilding, powerlifting, or general health use this calorie calculator online as a regular reference — checking it whenever their training volume or weight shifts significantly.
Frequently Asked Questions about the Calorie Calculator
BMR (Basal Metabolic Rate) is the calories your body burns at complete rest — breathing, circulation, cell repair. Think of it as what you'd burn lying still all day. TDEE (Total Daily Energy Expenditure) multiplies that by an activity factor to account for everything else you do. TDEE is the number you actually use to set nutrition targets.
A 500-calorie daily deficit below your TDEE targets roughly 0.5 kg (1 lb) of fat loss per week. A milder deficit of 250 calories per day gets you about half that rate but is far easier to maintain long-term. Don't drop below 1,200 calories/day for women or 1,500/day for men without medical supervision — extreme deficits risk nutritional deficiencies and muscle loss.
Harris-Benedict was developed in 1919 and consistently overestimates BMR by 5–15% in modern populations. Mifflin-St Jeor, published in 1990, was validated on a more representative sample and is now the preferred formula in most dietitian and clinical guidelines for estimating resting energy expenditure in healthy adults.
Within about 10% for most healthy adults. But individual variation in metabolism, body composition (muscle vs. fat ratio), hormones, and genetics means no formula is perfect. Use the result as a starting estimate and adjust based on your actual weight change after 2–3 weeks of consistent tracking. The formula can't know how you specifically respond.
Choose Sedentary (1.2) for a desk job with little or no exercise. Lightly Active (1.375) for 1–3 days of light exercise per week. Moderately Active (1.55) for 3–5 days of moderate exercise. Very Active (1.725) for hard training 6–7 days a week. Extra Active (1.9) for a physically demanding job or twice-daily training. When in doubt, go lower and adjust upward if you're losing weight faster than expected.
Yes — muscle burns more calories at rest than fat does. But the Mifflin-St Jeor equation uses total body weight, so it can't distinguish between lean mass and fat mass. Two people who are identical on paper but have different body compositions will have different actual TDEEs. Athletes with high lean mass tend to burn more than the formula predicts; people carrying more body fat may burn slightly less.
Every time your weight changes by about 5 kg (10 lbs), or whenever your activity level shifts significantly. As you lose weight your BMR drops — there's less mass to maintain — so your calorie target needs to come down too. Not adjusting for this is one of the main reasons fat loss plateaus after a few months of progress.
No. Mifflin-St Jeor was validated for adults roughly aged 19–78. Children and teenagers have significantly different calorie needs because of active growth. For anyone under 18, consult a pediatric dietitian or use a formula designed specifically for that age range, like the Schofield equation. This calculator also isn't appropriate during pregnancy or for conditions that significantly affect metabolism.