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Calorie Deficit Calculator — Lose Weight the Smart Way

Calorie Deficit Calculator — Lose Weight Fast | Free Online Tool
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Calorie Deficit Calculator

Calculate Your Daily Calorie Deficit · Free Instant Results

👁 59 views 📂 Fitness Calculators ⭐ Featured

📖 About This Calculator

The Calorie Deficit Calculator is a free online tool that calculates exactly how many calories you need to eat per day to reach your weight loss goal. It uses your personal details and activity level to first calculate your TDEE — Total Daily Energy Expenditure — and then subtracts your chosen deficit to give you a precise daily calorie target.

This calculator is built on the Mifflin-St Jeor formula, the most accurate and scientifically validated method for calculating calorie needs. It supports both Metric units (cm and kg) and Imperial units (feet, inches, and pounds), making it suitable for users worldwide.

Whether you are just starting your weight loss journey or fine-tuning your diet plan, this calculator gives you your TDEE, daily deficit, target calories, and a full weight loss timeline — all in seconds, with no sign-up or download required.

🚀 How to Use

1 Select your preferred unit system — Metric (cm/kg) or Imperial (ft/lbs).
2 Enter your Age in years.
3 Select your Gender — Male or Female.
4 Enter your Height in centimeters, or feet and inches.
5 Enter your Weight in kilograms or pounds.
6 Select your Activity Level from the dropdown:
7 Sedentary — little or no exercise
8 Lightly Active — exercise 1–3 days per week
9 Moderately Active — exercise 3–5 days per week
10 Very Active — hard exercise 6–7 days per week
11 Extra Active — very hard exercise or physical job
12 Select your Weekly Weight Loss Goal:
13 0.25 kg / 0.5 lbs — Slow and Steady
14 0.5 kg / 1 lb — Recommended
15 0.75 kg / 1.5 lbs — Moderate
16 1 kg / 2 lbs — Aggressive
17 Click Calculate Deficit.
18 Your TDEE, daily calorie deficit, target calories, and full weight loss timeline will appear instantly.
19 Tip: Click Reset to clear all fields and start a new calculation.

❓ Frequently Asked Questions

A calorie deficit means you are consuming fewer calories than your body burns in a day. When your body does not get enough calories from food, it turns to stored body fat for energy — which causes weight loss over time. For example, if your TDEE is 2500 calories and you eat 2000 calories per day, you are in a 500 calorie deficit. Since one kilogram of fat contains approximately 7700 calories, a daily deficit of 500 calories leads to roughly 0.5 kg of fat loss per week.
A deficit of 500 calories per day is widely recommended as the safest and most sustainable approach, leading to approximately 0.5 kg or 1 pound of fat loss per week. A deficit of 1000 calories per day can accelerate results but should only be followed under medical supervision. Cutting too many calories can cause muscle loss, fatigue, nutritional deficiencies, and metabolic slowdown. Most health professionals recommend never going below 1200 calories per day for women or 1500 calories per day for men without medical guidance.
TDEE stands for Total Daily Energy Expenditure — the total number of calories your body burns every day including your resting metabolism and all physical activity. Your TDEE is the baseline number you need to know before creating a deficit. If you eat at your TDEE, you maintain your weight. If you eat below it, you lose weight. If you eat above it, you gain weight. This calculator calculates your TDEE first and then subtracts your chosen deficit to give you your precise daily calorie target.
Not necessarily, and it can be counterproductive. A very large calorie deficit — such as eating only 1000 calories per day — can cause your body to break down muscle for energy, slow your metabolism, and make it harder to sustain the diet long term. A moderate deficit of 500 to 750 calories per day produces consistent fat loss while preserving muscle mass and energy levels. Sustainable, moderate deficits almost always produce better long-term results than extreme restriction.