Weight Loss Calorie Calculator

Weight Loss Calorie Calculator — Complete Guide

What this calculator does

This tool estimates how many calories you should eat each day to move from your current weight toward a target weight at a safe, sustainable pace. It first estimates your basal metabolic rate (BMR) — the energy your body burns at complete rest — then multiplies it by an activity factor to get your total daily energy expenditure (TDEE). The gap between TDEE and the amount you eat is your calorie deficit, and that deficit is what drives fat loss.

The result is a daily intake target plus a healthy range, an estimated weekly loss, and a projected number of weeks to reach your goal. The aim is not to starve the body but to create a deficit large enough to make progress and small enough to protect muscle and energy.

The calorie math

The formula uses the Mifflin-St Jeor equation, a widely used predictive method, with an optional 0.95 correction for East Asian body types. Activity factors range from 1.2 (sedentary) to 1.725 (very active). The key constant is 7,700 kcal, roughly the energy stored in 1 kg of body fat. Dividing a daily deficit by that figure tells you how fast weight should move; for example, a 500 kcal deficit is about 0.45 kg per week.

A worked example

A 30-year-old man, 175 cm tall, 80 kg, moderately active (factor 1.55), East Asian body type, aiming for 70 kg.

• BMR = 10×80 + 6.25×175 − 5×30 + 5 = 1,748.75 kcal
• East Asian correction: 1,748.75 × 0.95 ≈ 1,661 kcal
• TDEE = 1,661 × 1.55 ≈ 2,575 kcal
• Target loss of 10 kg suggests about 0.83 kg per week
• Daily deficit = 7,700 × 0.83 ÷ 7 ≈ 917 kcal
• Daily intake = 2,575 − 917 ≈ 1,658 kcal

At 1,658 kcal a practical macro split might be 110 g protein (440 kcal), 55 g fat (495 kcal) and about 181 g carbohydrate (723 kcal). Protein is set high enough to protect lean muscle while the deficit runs.

Tips, mistakes and edge cases

• Deficits are capped at roughly 1 kg per week; the tool will not fall below a safe minimum intake of 1,500 kcal for men and 1,200 kcal for women.
• Recalculate every few kilograms — a lighter body burns fewer calories, so the old intake slowly becomes a maintenance level.
• TDEE is an estimate, not a measurement. Treat the first two weeks as calibration and adjust based on real results.
• Very large deficits risk muscle loss, fatigue and stalled progress; a moderate deficit is easier to hold.
• Weight-change plates and water shifts are normal. Judge progress weekly, not daily.