Know your number — then every food choice gets easier

Knowing how many calories you need each day is the single most useful number in weight management. Eat above it and you gain; eat below it and you lose. Ask ten people for the answer and you’ll get ten different guesses — but your real number is personal: your age, size, gender, and activity level shape it, and a validated formula pins it down better than any rule of thumb.

This free calorie calculator estimates your daily calorie needs — maintenance, weight-loss, and weight-gain targets together — using the Mifflin-St Jeor formula, the most widely validated method available. Enter your details below and get your targets in under a minute.

How to Use This Calculator

1. Choose your units — switch between US units (feet, inches, pounds) and metric (centimeters, kilograms) at the top.
2. Enter your details — height, weight, and age. Use the sliders or type directly.
3. Select your gender — men and women burn calories at slightly different rates, so the formula adjusts accordingly.
4. Pick your activity level — be honest about a typical week, from sedentary (desk job, no exercise) to extra active (very hard training or physical work).
5. Choose your goal — lose weight, maintain, or gain weight. This highlights your hero number at the top.
6. Click “Calculate Calories” — the results panel shows your maintenance target big, plus every goal option with its expected weekly rate.

What Are Daily Calorie Needs?

A calorie is simply a unit of energy — in nutrition, “calories” really means kilocalories (kcal), and your body treats them as fuel. Your daily calorie need is the total energy your body uses in 24 hours, and it has two parts:

• BMR (Basal Metabolic Rate) — the calories your body burns at complete rest, just to keep you alive. For most adults this is 60–75% of total daily burn.
• Activity energy — everything else: walking, fidgeting, digesting food, and deliberate exercise.

Your maintenance calories, also called TDEE (Total Daily Energy Expenditure), are BMR multiplied by an activity factor. Eat exactly that and your weight stays stable. Eat less and the deficit comes from stored energy (body fat); eat more and the surplus gets stored. Roughly 3,500 calories equals one pound of body fat, which is why a daily deficit of 500 calories leads to about one pound of weight loss per week.

One thing to remember: this is an energy estimate, not a meal plan. Food quality, sleep, stress, and consistency matter enormously — but no plan works without knowing the number first.

The Formula + Worked Example

Worked example. A 35-year-old man, 80 kg, 175 cm tall, moderately active (multiplier 1.55):

1. BMR = (10 × 80) + (6.25 × 175) − (5 × 35) + 5 = 800 + 1,093.75 − 175 + 5 = 1,724 calories.
2. TDEE = 1,724 × 1.55 = 2,672 calories — his maintenance level.
3. Weight loss target = 2,672 − 500 = 2,172 calories/day (about 1 lb lost per week).
4. Weight gain target = 2,672 + 500 = 3,172 calories/day (about 1 lb gained per week).

The calculator never lets a weight-loss target fall below the recommended safety minimum — 1,200 calories/day for women and 1,500 for men — and it warns you if the floor is applied.

Limitations of Calorie Calculators

• It’s an estimate, ±10% or so. The Mifflin-St Jeor equation predicts BMR within about 10% for most adults; body composition, genetics, illness, medication, and dieting history can shift real needs outside the formula.
• Activity level is subjective. Overestimating exercise is the classic error — a brisk 30-minute walk burns roughly 120–150 calories, not 600. When in doubt, pick the lower level.
• People underreport intake by 20–40%. Forgotten snacks, cooking oils, and drinks don’t feel like “food,” but they count. Two weeks of honest tracking fixes this faster than any formula tweak.
• Your number moves. Lose 20 pounds and maintenance drops — the #1 cause of “plateaus” that aren’t really plateaus. Recalculate every 5–10 pounds lost or every couple of months.
• Not suitable for everyone. Children and teenagers (growth charts), pregnant or breastfeeding women, people with eating disorders, and anyone with a metabolic condition like thyroid disorders should get a personalized plan from a doctor or registered dietitian.

Treat the result as a starting point, and adjust based on how your weight actually moves over 2–3 weeks.

Tips for Healthy Calorie Habits

• Be honest about activity. Count only a typical week — a desk job with three gym sessions is “moderately active” at best.
• Start with mild loss. A 250–500 calorie daily deficit is far more sustainable than an aggressive one — slow losers keep the weight off.
• Re-run the calculator every 5–10 lb lost. As you get lighter, maintenance drops; recalculate monthly to avoid plateaus.
• Pair calories with protein. Keep protein around 1.6–2.2 g per kg of body weight while dieting to protect muscle.
• Prioritize food quality alongside quantity. Minimally processed foods, water instead of sugary drinks, and 7–9 hours of sleep make any calorie target dramatically easier to live with.
• Track intake for two weeks. You cannot hit a target you do not measure — weigh food or log it in an app to see where calories actually come from.
• Never crash below the floor. The calculator enforces 1,200/1,500 minimums — treat those as hard limits, not suggestions.

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Turning Your Number Into a Goal

The figure from the calculator is your maintenance level. Adjust it to match your goal:

The 500 kcal step is popular for a reason: a pound of body fat stores roughly 3,500 kcal, so a 500 kcal daily deficit adds up to about a pound (roughly 0.45 kg) per week. Stay above the usual safety floors — about 1,200 kcal/day for women and 1,500 kcal/day for men — unless a clinician supervises you, and recalculate after every 5 to 10 pounds of weight change, because a lighter body burns less.

If you know your body fat percentage, the Katch-McArdle formula refines the estimate using lean mass instead: BMR = 370 + 21.6 × lean mass in kg. A 70 kg person at 20 percent body fat has 56 kg of lean mass, giving BMR = 370 + 1,209.6 ≈ 1,580 kcal/day.

Frequently Asked Questions