calctube
🍎 Health Last tested2026-05-25

Calorie Deficit Calculator.

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Quick answer

A 500 kcal/day deficit burns roughly 0.45 kg (1 lb) of fat per week. Enter your details below to get your personal daily calorie target and a timeline to your goal weight.

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Calorie Deficit Calculator

Daily Calorie Target
1,794
kcal/day
500 kcal below TDEE
Estimated Time
22
weeks to goal
≈ 6 months
Your TDEE
2,294
kcal/day (maintenance)
BMR: 1,480 kcal
✨ Live · Mifflin-St Jeor · 1 kg fat ≈ 7,700 kcal · 1,200 kcal/day minimum enforced · For educational use only
📖 How to use

Your path to goal weight.

1

Enter your sex, age, height, and current weight

2

Enter your target weight and select your activity level

3

Choose a weight loss pace (Slow to Aggressive)

4

Get your daily calorie target and estimated weeks to reach goal

🧮 The formula

The calorie-deficit equation.

Step 1: Find TDEE
TDEE = BMR × Activity Multiplier
Step 2: Set Daily Target
Daily Calories = TDEE − Deficit
Step 3: Estimate Timeline
Weeks = (weight to lose × 7,700 kcal) ÷ (Deficit × 7)

1 kg of body fat ≈ 7,700 kcal (≈ 3,500 kcal per lb). Timeline is an estimate. Real-world results vary with water retention, muscle gain, and metabolic adaptation.

A calorie deficit is the foundation of all weight loss strategies, regardless of which diet you follow. Whether it's low-carb, intermittent fasting, or keto, the common mechanism is eating fewer calories than you burn.

The calculator uses the Mifflin-St Jeor equation to estimate your BMR, then multiplies by an activity factor to get TDEE. Your daily calorie target is TDEE minus your chosen deficit, with a hard floor of 1,200 kcal/day to prevent dangerously low intake.

Pace matters: A slow pace (−250 kcal/day) is sustainable for months but takes longer. An aggressive pace (−1,000 kcal/day) reaches the goal faster but increases the risk of muscle loss and rebound. Most nutrition professionals recommend −500 kcal/day as the sweet spot.

Sources: NIH Practical Guide to Obesity (2000) · CDC Healthy Weight: Calories

❓ FAQ

Common questions.

How many calories do I need to lose weight?
You need to eat fewer calories than you burn (your TDEE). A deficit of 500 kcal/day leads to roughly 0.45 kg (1 lb) of fat loss per week. This calculator computes your personal TDEE via the Mifflin-St Jeor equation, then subtracts your chosen deficit to give you a daily calorie target.
How long will it take to reach my target weight?
Time to goal depends on how much weight you want to lose and the size of your daily deficit. The formula is: Weeks = (weight to lose in kg × 7,700 kcal) ÷ (daily deficit × 7). A 500 kcal/day deficit burns roughly 0.45 kg/week, so losing 10 kg takes about 22 weeks at a moderate pace.
Is a 1,000 kcal/day deficit safe?
A 1,000 kcal/day deficit is considered aggressive and may lead to muscle loss, nutrient deficiencies, and metabolic slowdown. Most health authorities recommend a maximum deficit of 500–750 kcal/day for sustainable fat loss. The calculator flags this and recommends a moderate pace.
Why does the calculator enforce a 1,200 kcal minimum?
Eating below 1,200 kcal/day (for women) or 1,500 kcal/day (for men) makes it nearly impossible to meet daily nutritional needs, regardless of deficit. This calculator caps the result at 1,200 kcal to prevent dangerously low targets. Consult a doctor or dietitian if your TDEE minus your desired deficit falls below this.
What is the difference between TDEE and BMR?
BMR (Basal Metabolic Rate) is the calories burned at complete rest: no movement at all. TDEE (Total Daily Energy Expenditure) multiplies BMR by your activity level to account for exercise and daily movement. You should always base a calorie deficit on TDEE, not BMR.
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