Sedentary (Little to no exercise)
Lightly Active (1-3 days/week)
Moderately Active (3-5 days/week)
Very Active (6-7 days/week)
Extra Active (Physical job or training)
Lose 0.5 lbs per week (Mild)
Lose 1 lb per week (Recommended)
Lose 1.5 lbs per week (Strict)
Lose 2 lbs per week (Aggressive)
Your Daily Calorie Plan
Basal Metabolic Rate (BMR):–
Maintenance Calories (TDEE):–
Daily Deficit Required:–
To reach your goal, consume:–calories per day
*Ensure you prioritize protein and nutrient-dense foods.
Understanding Your Calorie Deficit Results
Creating a calorie deficit is the fundamental principle behind weight loss. By consuming fewer calories than your body burns, you force your body to use stored energy (fat) to function. This calculator uses the Mifflin-St Jeor equation, widely considered the most accurate method for estimating calorie needs.
What do these numbers mean?
BMR (Basal Metabolic Rate): The number of calories your body burns just to stay alive (breathing, circulation, cell production) at complete rest.
TDEE (Total Daily Energy Expenditure): Your BMR plus the calories burned through movement and exercise. This is your "maintenance" number—if you eat this amount, your weight stays the same.
Target Calories: The specific daily intake required to achieve your desired weight loss rate.
How to Stick to Your Deficit
Consistency is more important than perfection. A deficit of 500 calories per day typically results in 1 pound of weight loss per week (since 1 lb of fat ≈ 3,500 calories). Here are strategies to succeed:
Track Accurately: Use a food scale and a tracking app. Humans are notoriously bad at estimating portion sizes.
Focus on Protein: Protein increases satiety and helps preserve lean muscle mass while you lose fat.
Don't Drink Your Calories: Swap sugary sodas and lattes for water, black coffee, or tea.
Adjust Over Time: As you lose weight, your BMR decreases. Recalculate your numbers every 10-15 lbs lost to keep progress steady.
Is a Higher Deficit Better?
Not necessarily. While losing 2 lbs a week sounds appealing, aggressive deficits can lead to muscle loss, fatigue, nutrient deficiencies, and metabolic adaptation. A moderate deficit (0.5 to 1 lb per week) is often more sustainable long-term and helps keep the weight off permanently.
function calculateDeficit() {
// 1. Get Inputs
var genderMale = document.getElementById('genderMale').checked;
var age = parseFloat(document.getElementById('age').value);
var feet = parseFloat(document.getElementById('heightFeet').value);
var inches = parseFloat(document.getElementById('heightInches').value);
var weightLbs = parseFloat(document.getElementById('currentWeight').value);
var activity = parseFloat(document.getElementById('activityLevel').value);
var goal = parseFloat(document.getElementById('weightGoal').value);
// 2. Validate Inputs
if (isNaN(age) || isNaN(feet) || isNaN(inches) || isNaN(weightLbs) || age < 1 || weightLbs < 1) {
alert("Please enter valid numbers for age, height, and weight.");
return;
}
// 3. Conversions
var totalInches = (feet * 12) + inches;
var heightCm = totalInches * 2.54;
var weightKg = weightLbs / 2.20462;
// 4. Calculate BMR (Mifflin-St Jeor Equation)
// 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
var bmr = (10 * weightKg) + (6.25 * heightCm) – (5 * age);
if (genderMale) {
bmr += 5;
} else {
bmr -= 161;
}
// 5. Calculate TDEE and Deficit
var tdee = bmr * activity;
// 1 lb of fat approx 3500 calories. Weekly goal * 3500 / 7 days = daily deficit
var dailyDeficit = (goal * 3500) / 7;
var targetCalories = tdee – dailyDeficit;
// Safety Floor Check
var minCalories = genderMale ? 1500 : 1200;
var warning = "";
// 6. Display Results
document.getElementById('displayBmr').innerHTML = Math.round(bmr) + " kcal";
document.getElementById('displayTdee').innerHTML = Math.round(tdee) + " kcal";
document.getElementById('displayDeficit').innerHTML = "-" + Math.round(dailyDeficit) + " kcal";
var finalTarget = Math.round(targetCalories);
// Color coding for aggressive deficits
var resultElement = document.getElementById('displayTarget');
if (finalTarget < minCalories) {
resultElement.style.color = "#e67e22"; // Orange warning
// We still show the number but maybe user should know it's low.
// For this simple calculator, we just show the calculation.
} else {
resultElement.style.color = "#27ae60"; // Green good
}
resultElement.innerHTML = finalTarget;
// Show result container
document.getElementById('cd-result-area').style.display = 'block';
}