Calorie Calculator

Rough maintenance calorie estimates for a moderately active adult. Your real number depends on age, height, sex, and body composition — use the calculator above for a personalised figure.

To lose about 1 lb (0.45 kg) per week, eat ~500 calories below maintenance. To gain, eat ~300-500 above. These are starting points — adjust based on 2-4 weeks of real results.

The calorie calculator estimates three numbers: your BMR (the calories you burn at complete rest), your TDEE (total calories burned including activity), and a daily calorie target based on your goal. It uses the Mifflin-St Jeor equation, the most accurate general BMR formula validated in clinical research, and applies a standard activity multiplier.

BMR — Basal Metabolic Rate

The energy your body uses just to stay alive: heartbeat, breathing, organ function, cell repair. If you stayed in bed all day, this is roughly what you'd burn. BMR is usually 60-70% of total daily burn.

TDEE — Total Daily Energy Expenditure

BMR plus everything else: walking, working, exercising, fidgeting, digesting food. This is the number that matters for weight management. Eat at your TDEE to maintain, below it to lose, above it to gain.

The formula: TDEE = BMR × activity multiplier, where the multiplier ranges from 1.2 (sedentary) to 1.9 (extremely active).

Published in 1990, this is the formula most dietitians use:

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

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

It's more accurate than the older Harris-Benedict equation (1919, revised 1984), which tends to overestimate by 5-15% for modern populations.

Most people overestimate their activity. Here's the honest breakdown:

Roughly 3,500 calories equals 1 pound of body fat (this is an approximation — the real number varies). So:

• 500 cal/day deficit ≈ 1 lb (0.45 kg) loss per week
• 750 cal/day deficit ≈ 1.5 lb per week
• 1,000 cal/day deficit ≈ 2 lb per week (aggressive, harder to sustain)

Calories determine weight change. Macros determine body composition and how you feel. Our default split (30% protein, 40% carbs, 30% fat) works for most goals.

Protein (4 cal/gram)

The most important macro for body composition. Aim for 1.6-2.2 g per kg of body weight if losing fat or building muscle. High protein preserves muscle during a deficit and keeps you full.

Carbohydrates (4 cal/gram)

Your body's preferred fuel, especially for high-intensity exercise. Not inherently fattening — total calories matter more than carb amount for weight.

Fat (9 cal/gram)

Essential for hormone production and vitamin absorption. Don't go below about 0.5 g per kg body weight. Fat is calorie-dense, so it's easy to overeat.

How many calories should I eat to lose weight?

Calculate your TDEE, then subtract 500 for about 1 lb/week loss. For a 160 lb moderately active adult with a TDEE around 2,350, that's roughly 1,850 calories/day. Use the calculator for your exact number.

Why am I not losing weight in a deficit?

Three usual culprits: underestimating intake (unlogged snacks, oils, drinks add up fast), overestimating activity (the multiplier might be too high), and water retention masking fat loss. Track intake accurately for 2 weeks and judge by the trend, not daily fluctuations.

Is the 3,500 calories = 1 pound rule accurate?

It's a useful approximation but not exact. The real figure varies with what tissue you lose (fat vs muscle vs water) and metabolic adaptation. Over weeks it averages out reasonably well for planning.

Should I eat back exercise calories?

If your activity multiplier already accounts for your typical exercise (which ours does), don't add exercise calories on top — you'd be double-counting. Only eat back exercise calories if you used the sedentary multiplier and log workouts separately.

Does metabolism slow down with dieting?

Somewhat. Adaptive thermogenesis means your body becomes slightly more efficient during prolonged deficits. This is why periodic maintenance breaks (eating at TDEE for 1-2 weeks) help long-term fat loss. The effect is real but often overstated.