Calorie Deficit Calculator

A calorie deficit is the gap between the calories your body uses each day and the calories you eat. When that gap is negative (you eat fewer calories than you burn), your body taps stored energy and you lose weight over time.

Most adults can sustainably lose roughly 0.5 kg (about 1 pound) per week with a daily deficit of around 500 kcal. That's the default our calorie deficit calculator uses, and it's the level the World Health Organization and most clinical guidelines describe as safe for healthy adults.

The math is simple, but actually staying in a deficit is the hard part. That's why this page does two things: it gives you the number, then it turns the number into a plan you can eat today.

We use the Mifflin–St Jeor equation, the formula clinicians and registered dietitians rely on most. It estimates your basal metabolic rate (BMR), the calories you'd burn lying still, from your weight, height, age, and sex.

We multiply BMR by an activity factor (1.2–1.9) to estimate your total daily energy expenditure (TDEE). Then we subtract 500 kcal for fat loss, hold steady for maintenance, or add 300 kcal for a lean gain.

There's a safety floor: 1,200 kcal/day for women and 1,500 kcal/day for men. If your deficit pushes the target below that floor, we clamp it. Eating less than that long-term tends to backfire. Metabolism adapts, energy drops, and most people quit.

Knowing you need 1,650 kcal doesn't tell you what to eat. That's where most calculators stop and most food diaries fall apart. The math is right, but the day is unstructured, so by 8pm you're improvising.

Hit "Get my first day plan" and we assemble a real day around your target: 3–4 meals, total within 10% of your number, with portion sizes scaled so you don't have to do mental math. The plan is built to feel like food, not a spreadsheet.

It's one plan, on us. If you want a fresh plan every day, plus automatic calorie tracking that learns your habits and stops feeling like homework. That's what Nuvvoo does.