Calorie Deficit Calculator | Safe & Sustainable Weight Loss
Calorie Deficit Calculator | Safe & Sustainable Weight Loss
Meet Alex. He weighs 90 kg and wants to reach 75 kg in the next 12 weeks. He’s tried fad diets before, but they failed — leaving him hungry, exhausted, and frustrated.
Alex wonders: “How many calories should I eat each day to lose weight safely? How big of a deficit is realistic? Can I hit my goal without starving myself?”
This is exactly why the Calorie Deficit Calculator exists. It takes your current weight, height, age, gender, activity level, goal weight, and timeline, and calculates exactly how many calories you should eat each day to lose weight safely and sustainably.
What Is a Calorie Deficit Calculator?
A calorie deficit calculator is a tool that helps you determine:
- How many calories your body burns daily (Total Daily Energy Expenditure – TDEE).
- How many calories you need to eat to lose weight at a safe, sustainable pace.
- Your weight loss timeline — so you can track progress and stay realistic.
It combines your Basal Metabolic Rate (BMR) with your activity level to give you an accurate estimate of daily calorie needs.
Why Is This Important?
- Prevents extreme dieting: Avoid starvation and nutrient deficiencies.
- Supports sustainable weight loss: Safe calorie deficits prevent rebound weight gain.
- Maintains energy and muscle: A moderate deficit ensures fat loss, not muscle loss.
- Tracks realistic goals: Know exactly how many weeks it may take to reach your target.
- Personalized guidance: Tailored for your age, gender, weight, activity, and goal.
Formula & Calculations
1. Basal Metabolic Rate (BMR)
BMR represents calories burned at rest. The calculator uses the Mifflin-St Jeor equation, which is widely accepted:
- Men: BMR = 10 × weight(kg) + 6.25 × height(cm) – 5 × age + 5
- Women: BMR = 10 × weight(kg) + 6.25 × height(cm) – 5 × age – 161
2. Total Daily Energy Expenditure (TDEE)
TDEE adjusts BMR for your activity level:
| Activity Level | Multiplier |
| Sedentary (little or no exercise) | 1.2 |
| Lightly Active (1–3 days/week) | 1.375 |
| Moderately Active (3–5 days/week) | 1.55 |
| Very Active (6–7 days/week) | 1.725 |
| Extremely Active (physical job + training) | 1.9 |
TDEE = BMR × Activity Multiplier
3. Daily Calorie Deficit
To lose weight safely, a moderate deficit of 500–1000 calories/day is recommended (≈0.5–1 kg per week).
Daily Calories = TDEE – Calorie Deficit
4. Weight Loss Timeline
Weeks = (Current Weight – Goal Weight) ÷ Weekly Weight Loss
Example:
- Current Weight = 90 kg
- Goal Weight = 75 kg
- Weekly Deficit = 0.5–1 kg/week
- Timeline = 15–30 weeks depending on pace
How the Calculator Works – Step by Step
- Enter your current weight, height, age, and gender – This calculates your BMR.
- Select your activity level – Sedentary → Extremely Active.
- Enter your goal weight – The target you want to reach.
- Set the number of weeks to reach the goal – Optional; the calculator will suggest a safe pace if left blank.
- Press Calculate – You’ll get:
- BMR: Calories your body burns at rest.
- TDEE: Calories burned per day including activity.
- Daily Calorie Deficit: How much to reduce safely.
- Target Calories: Daily calories to hit your goal.
- BMR: Calories your body burns at rest.
Weight Loss Timeline: Weeks needed to reach your goal safely.
