Calorie Deficit Calculator
Scientifically calculate how many calories to eat to lose weight safely
Your Personal Calorie Planner
Enter your details below to calculate how many calories to eat to lose weight based on your unique metabolic profile.
Male
Female
Required for BMR calculation logic.
Metabolism slows slightly with age.
Please enter a valid age (15-100).
Height affects your total surface area and energy expenditure.
Please enter a valid height (100-250 cm).
Your starting point for the calculation.
Please enter a valid weight (30-300 kg).
Sedentary (Little to no exercise)
Lightly Active (Exercise 1-3 days/week)
Moderately Active (Exercise 3-5 days/week)
Very Active (Exercise 6-7 days/week)
Extra Active (Very hard exercise/physical job)
Be honest for the most accurate result.
Mild Weight Loss (0.25 kg/week)
Standard Weight Loss (0.5 kg/week)
Extreme Weight Loss (1.0 kg/week) – Not recommended long term
0.5 kg/week is generally considered sustainable.
Daily Calorie Target
1850
Calories / Day
To achieve your selected weight loss goal.
Maintenance Calories (TDEE)
2350
Calories to maintain current weight
Basal Metabolic Rate (BMR)
1500
Calories burned at complete rest
Daily Calorie Deficit
-500
Energy shortfall created
Formula Used: Mifflin-St Jeor Equation × Activity Factor – Calorie Deficit
Suggested Macronutrient Breakdown (Balanced)
A balanced breakdown helps maintain muscle while losing fat.
| Macronutrient | Percentage | Grams per Day | Calories |
|---|
Projected Weight Loss Timeline (8 Weeks)
— Projected Weight
— Maintenance Baseline
What is "Calculate How Many Calories to Eat to Lose Weight"?
To calculate how many calories to eat to lose weight is the process of determining your specific energy needs to create a "calorie deficit." A calorie deficit occurs when you consume fewer calories than your body burns in a day. This fundamental principle of thermodynamics drives weight loss.
This calculation is not a guessing game. It uses established metabolic science to estimate your Total Daily Energy Expenditure (TDEE) and subtracts a specific amount of energy (calories) to force your body to utilize stored fat for fuel. Whether you are an athlete cutting for a competition or someone looking to improve their general health, knowing how to calculate how many calories to eat to lose weight is the first step toward a sustainable physique change.
Common Misconception: Many people believe they must eat 1,200 calories or less to lose weight. This is often dangerous and sustainable. Properly calculating your needs usually results in a higher, more manageable calorie target that preserves muscle mass and metabolism.
Formula and Mathematical Explanation
The logic behind the calculator relies on the Mifflin-St Jeor Equation, widely considered the most accurate formula for estimating Basal Metabolic Rate (BMR) in clinical settings. Here is how we calculate how many calories to eat to lose weight step-by-step:
Step 1: Calculate BMR
Your BMR is the energy your body needs just to keep organs functioning.
- Men: (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) + 5
- Women: (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) – 161
Step 2: Calculate TDEE
We multiply BMR by an Activity Factor to find your maintenance level.
| Variable | Meaning | Typical Multiplier |
|---|---|---|
| Sedentary | Desk job, little exercise | 1.2 |
| Lightly Active | Light exercise 1-3 days/week | 1.375 |
| Moderately Active | Moderate sports 3-5 days/week | 1.55 |
| Very Active | Hard exercise 6-7 days/week | 1.725 |
Step 3: Apply the Deficit
To lose 1 lb (approx 0.45 kg) of fat, you need a deficit of roughly 3,500 calories. Therefore:
- 0.5 kg/week loss: TDEE – 500 calories/day
- 1.0 kg/week loss: TDEE – 1000 calories/day
Practical Examples
Understanding the numbers helps clarify why individual results vary when you calculate how many calories to eat to lose weight.
Example 1: The Office Worker
Profile: Sarah, 35 years old, Female, 165cm, 80kg. Sedentary job.
Goal: Lose 0.5kg per week.
- BMR Calculation: Approx 1,560 kcal.
- TDEE Calculation: 1,560 × 1.2 (Sedentary) = 1,872 kcal (Maintenance).
- Target: 1,872 – 500 = 1,372 calories/day.
Interpretation: Sarah needs to eat roughly 1,370 calories. If she eats 1,872, she stays the same weight.
Example 2: The Active Construction Worker
Profile: Mike, 28 years old, Male, 180cm, 95kg. Very Active job.
Goal: Lose 0.5kg per week.
- BMR Calculation: Approx 2,000 kcal.
- TDEE Calculation: 2,000 × 1.725 (Very Active) = 3,450 kcal.
- Target: 3,450 – 500 = 2,950 calories/day.
Interpretation: Mike can eat nearly 3,000 calories and still lose weight because his expenditure is so high. This highlights why you cannot use a generic number for everyone.
How to Use This Calculator
- Enter Biometrics: Input your exact age, height, and current weight. Accuracy here ensures a precise BMR.
- Select Activity: Choose the level that best describes your average week. If unsure, lean towards "Sedentary" or "Lightly Active" to avoid overestimating calories burned.
- Choose Goal: Select how fast you want to lose weight. We recommend 0.5kg/week for sustainable results.
- Review Results: The tool will instantly calculate how many calories to eat to lose weight. Use the "Copy Results" button to save your targets.
Key Factors That Affect Results
When you calculate how many calories to eat to lose weight, several real-world factors influence the outcome:
- Metabolic Adaptation: As you lose weight, your body requires less energy to move. You must recalculate your needs every 5-10kg lost.
- TEF (Thermic Effect of Food): Protein requires more energy to digest than fats or carbs. A high-protein diet can effectively increase your TDEE slightly.
- NEAT (Non-Exercise Activity Thermogenesis): Fidgeting, walking, and standing count significantly. Two people with the same workout routine may burn very different amounts based on their NEAT.
- Hormonal Fluctuations: For women especially, water retention during the menstrual cycle can mask fat loss on the scale, even if you hit your calorie targets.
- Underestimating Intake: Studies show people underreport food intake by up to 50%. Weighing food is critical for accuracy.
- Sleep & Stress: High cortisol (stress hormone) and lack of sleep can lower metabolic rate and increase hunger cues, making adherence difficult.
Frequently Asked Questions (FAQ)
Is the result 100% accurate?
No formula is perfect. These calculations are statistical estimates. Treat the result as a starting point, track your weight for 2 weeks, and adjust up or down by 100 calories if necessary.
Should I eat back my exercise calories?
Generally, no. The activity multiplier already accounts for your exercise. Adding extra calories for a workout often leads to "double counting" and stalls weight loss.
What is the minimum calorie intake?
Medical guidelines suggest men should not drop below 1,500 and women below 1,200 calories without medical supervision to ensure nutrient sufficiency.
Why did I stop losing weight?
This is a plateau. It likely means you have lost enough weight that your new maintenance level is lower. You need to recalculate how many calories to eat to lose weight based on your new body weight.
Can I lose weight faster than 1kg per week?
It is possible but risky. Rapid weight loss often results in muscle loss, gallstones, and metabolic slowdown. Slow and steady preserves muscle.
Does nutrient timing matter?
For total weight loss, total daily calories matter more than when you eat them. However, eating protein spaced throughout the day aids satiety.
What if I have hypothyroidism?
Your BMR might be 10-20% lower than the standard formula predicts. Consult an endocrinologist for a tailored plan.
Is it better to cut calories or add cardio?
A combination is best. Creating a deficit solely through food can leave you hungry, while doing it solely through cardio is time-consuming. Balance is key.
Related Tools and Internal Resources
Explore our suite of health and financial planning tools to optimize your lifestyle:
- BMI Calculator for Adults – Determine if your weight falls within a healthy statistical range.
- Macronutrient Split Calculator – Optimize your protein, fat, and carb ratios for muscle gain.
- TDEE Calculator – Find your total daily energy expenditure without the deficit.
- Body Fat Percentage Estimator – Estimate body composition using tape measurements.
- Ideal Weight Calculator – Find the target weight range for your height and frame size.
- Basal Metabolic Rate Tool – Focus purely on your resting energy expenditure.