Warning: Consuming less than 1,200 calories is generally not recommended for women.';}else if(target<1500 && gender==='male'){var warning='
Warning: Consuming less than 1,500 calories is generally not recommended for men.';}else{var warning=";}document.getElementById('summaryResult').innerHTML='Target: '+Math.round(target)+' kcal/day';var details='To maintain your current weight, you need approximately '+Math.round(tdee)+' calories per day (TDEE).';if(showSteps){details+='
Breakdown:
Basal Metabolic Rate (BMR): '+Math.round(bmr)+' kcal
Activity Multiplier: '+activity+'x
Selected Deficit: -'+deficit+' kcal';}details+=warning;document.getElementById('detailResult').innerHTML=details;}
Calculator Use
The calorie deficit calculator is an essential tool for anyone looking to lose weight in a scientific and sustainable manner. By calculating your daily energy needs and subtracting a specific amount, you can determine exactly how many calories you should consume to reach your weight loss goals.
To use this calculator effectively, simply enter your personal metrics, including your current weight and activity level. The calculator will provide your Total Daily Energy Expenditure (TDEE) and your target caloric intake for weight loss.
- Gender and Age
- Metabolic rates vary by sex and decrease gradually as we age.
- Weight and Height
- The more mass you have, the more energy your body requires to function, even at rest.
- Activity Level
- This multiplier accounts for the calories burned through movement and exercise.
How It Works
Weight loss is fundamentally driven by thermodynamics: energy in versus energy out. To lose weight, you must consume fewer calories than your body burns. This calculator uses the Mifflin-St Jeor Equation, which is currently considered the most accurate formula for predicting Basal Metabolic Rate (BMR).
Men: BMR = (10 × weight in kg) + (6.25 × height in cm) – (5 × age) + 5
Women: BMR = (10 × weight in kg) + (6.25 × height in cm) – (5 × age) – 161
Once the BMR is established, it is multiplied by an Activity Factor to find the TDEE. A calorie deficit calculator then subtracts your chosen deficit (typically 500 calories for 1 pound of weight loss per week) from that TDEE total.
- BMR: The energy burned just to keep your organs functioning while lying in bed.
- TDEE: The total energy used throughout the day including walking and exercise.
- Deficit: The gap between what you burn and what you eat, forced to be filled by stored body fat.
Calculation Example
Example: A 35-year-old male who weighs 90kg and is 180cm tall with a "Moderately Active" lifestyle (1.55x factor) wants to lose weight.
Step-by-step solution:
- BMR = (10 × 90) + (6.25 × 180) – (5 × 35) + 5 = 1,855 calories.
- TDEE = 1,855 × 1.55 = 2,875 calories (Maintenance).
- Apply Deficit = 2,875 – 500 = 2,375 calories.
- Daily Target: 2,375 calories per day to lose roughly 0.5kg per week.
Common Questions
What is a safe calorie deficit?
Most health professionals recommend a deficit of 500 to 750 calories per day, which typically results in a weight loss of 1 to 1.5 pounds (0.5 to 0.7 kg) per week. Extremely aggressive deficits can lead to muscle loss and nutrient deficiencies.
Can I lose weight without exercise?
Yes, weight loss is primarily driven by diet. However, exercise increases your TDEE, allowing you to eat more while still maintaining a deficit, and it helps preserve lean muscle mass during the process.
How often should I recalculate?
You should use the calorie deficit calculator every 5-10 pounds lost. As your body mass decreases, your BMR also drops, meaning you need fewer calories to maintain your new, smaller weight.