Calorie Calculator

A calorie calculator gives you a starting daily intake target based on three things: your BMR (calories burned at rest), your activity level (how much you move on top of that), and your goal (lose, maintain, or gain). The result is a personalized number that's far more useful than generic advice like "women need 2,000 calories."

The fundamental equation of weight management is simple: eat fewer calories than you burn to lose weight, eat more to gain. Everything else — meal timing, macros, food choices — affects how easy the deficit is to maintain and what you lose (fat vs. muscle), but the deficit itself is what drives the change.

30-year-old woman, 65 kg, 165 cm, moderately active, goal: lose weight:

• BMR (Mifflin-St Jeor) = (10 × 65) + (6.25 × 165) − (5 × 30) − 161 = 1,370 cal
• Maintenance = 1,370 × 1.55 = 2,124 cal
• Target for fat loss (−500): 1,624 cal/day
• Expected weekly loss: ~1 lb (0.45 kg)

After 4 weeks she's lost ~3.5 lb. Her new maintenance is slightly lower, so she may recalculate and drop 100 calories if loss stalls.

• Starting a fat-loss phase — establishing a realistic daily target.
• Reverse dieting — slowly increasing calories after a long deficit.
• Bulking — building muscle with a 200–500 calorie surplus.
• Recomposition — eating near maintenance while training to lose fat and build muscle simultaneously.
• Re-evaluating after a plateau — recalculating as your body weight or activity changes.

• Going too low. Aggressive deficits accelerate muscle loss, slow metabolism, and rarely last more than a few weeks.
• Underestimating intake. Self-reported calorie tracking is famously inaccurate. Use a food scale for 1–2 weeks to recalibrate.
• Trusting fitness-tracker calorie burns. They overestimate by 20–40%. Don't eat them all back.
• Skipping protein. Without sufficient protein (0.7–1g per lb of body weight), a calorie deficit causes more muscle loss than necessary.
• Treating the number as static. Your maintenance drops as you lose weight. Recalculate every 10–15 lb.